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Deep Sleep: Everything You Need To Know (+65 Best Sleep Quality Tips)

Jun 05, 2019

Blog Post Summary 


It's 6:00. Getting up in the morning. Quick shower. Say hello to your loved ones. Make breakfast quickly. Brush teeth. Travel to work. Work for 8 hours. Off. Dinner. 


Finally: time for fun...

But complete some chores first.

19.00. Really done now.

Watch TV.




One more program...


Just a little longer.

"Oh, that's interesting!"


"Should have gone to bed an hour ago..."

But who cares?

You can sleep in on the weekend, right? It's Thursday so only one more day...


Let's get to bed...


And juuuuust a few seconds later--or at least, that's what it feels like--it's already time to wake up. You just got 6 hours of sleep. Sure, you're a little underslept but you can survive on that easily, right?

Surely, it's the same pattern every single week:

You'll lose some deep sleep during the week. But you'll make up during the weekend...

No harm done...

Or is there?

Surprise, surprise: You cannot make up for lost sleep. At all.

Poor sleep always has negative health effects. 

As a result, moreover, you'll go about your day sleep deprived. And on Saturday, you'll sleep in till the afternoon. 

But sleeping in can't hurt either, right?

Well, sleeping in does hurt. Varying sleep times throughout the week create what is called "social jet lag".


The rhythm inside your body can only adjust about an hour at the maximum per day. Change that rhythm quicker and sleep quality goes down.


Now, maybe you're already planning your sleep properly. Maybe you're going to bed at the same time most days. Maybe you're really prioritizing your sleep just like your diet and exercise routine.

In that case, congratulations. But even then, I still have something to offer to you.

picture of a stuffed animal laying on bed reading, symbolizing a joke
How many people feel at 10 PM... no, 4 PM.


In fact, this guide offers you 65 strategies for improving deep sleep.

This 30,000-words+ tour de force teaching you everything you need to know about improving sleep quality.

Basically, you're getting an e-book on sleep optimization for free. So enjoy!

Don't worry, you don't have to implement every tip. You can simply start with the best one - those at the beginning of the list...

So let's get the party started.

I'll commence with the basics though - the reason you're reading this blog post anyway:

Why deep sleep matters

Ever wanted to own the "elixir of youth"? Ever wanted to turn back the time on your age, and regain the vitality of your twenties?

(And if you're in your 20s: ever wanted to kick even more ass than you already do?)

No need for a magic pill. No need for shortcuts.

Deep sleep is the elixir of youth. 

Let me explain:

During deep sleep - also called "slow wave sleep" or "delta sleep" - a synchronous pattern of electricity form in front of your brain that moves to its back. Neurons, which are brain cells, fire at a quick rate followed by rest.

That deep sleep is massively important for mental and physical recovery. Growth hormone is released at that time, which slows down aging.

Brain cells called "glial cells" - important for regenerating "myelin" which speeds up nerve conductivity are also restored.

Brain cells also communicate with each other during deep sleep and connections between them are strengthened. That way all that you've learned becomes integrated.

There's a catch though:

Deep sleep deteriorates as you age, unfortunately. In fact, both deep sleep quality (strength of the electric pattern) and quantity (total time spent in deep sleep) go down over time.

But you know what?

But that decline may not be guaranteed. And with sleep tips in this blog post you can improve your deep sleep. You just need to be disciplined and consistent. I'm not saying you it's easy though - it probably requires effort in the beginning. 

So let's start at the beginning:

Prioritizing sleep: developing sleep habits

Surely you know:

Most important things in life come with some sacrifice. If you want to be an Olympic athlete, you have to give something up. Same for being a doctor or self-made millionaire.

And here's the kicker:

The biggest problem with deep sleep is not that you have to work hard for it. Sleeping is not like gym time...

The biggest problem is that you need to change your philosophy around sleep. How? Sipmle: Sleep needs to be a priority.

The problem?

For most people sleep is an afterthought. A third of all persons living in the developed world, therefore, walk around sleep deprived.

Another third or more doesn't sleep as well as they can (and should)...

No worries right?

You feel fiiiiine on 6 hours of sleep. Sure, sleeping 8 hours makes you a bit more alert, awake, and sharp. But no big difference, correct?

Not so fast...

Even with a regular 6 hours of sleep you're probably sleep deprived. And with regular social jet lag on the weekend, the problem gets even worse. 

Add some poor sleep quality on top of that and the real trouble starts...

In fact, only a few people can get away with sleeping very little all the time. If you're a  genetic freak you may indeed only need 4-5 hours. And if you could have slept longer this morning then you're not one of them.

How about 6 hours?

Some poeple can handle that - but only if their sleep quality is great. And the only way to get good sleep quality is to prioritize sleep.

If not, sleep deprivation is the result...

Why sleep needs to be prioritized

So let's talk about sleep deprivation...

Sleep deprivation is linked to increased risks for all kinds of diseases, such as heart disease, Alzheimer's, cancer, diabetes, obesity, and more. You'll also weaken your immune system, learn more poorly, you'll make more mistakes, have less self-control, feel worse, perform worse...

You get the drill...

And you yourself are not the only one at risk.


Many innocent people get killed on the road every year due to sleep deprived drivers.

Shocking but true...

So there's just one solution: prioritize sleep.

The reason is simple: You need sleep just like you need food and movement and sunlight exposure. 

Sleep is is the foundation that turns back the aging clock every single night. If you don't sleep, that clock speeds up. 

With perfect sleep, that clock slows down. Sleep thus creates time in your life, which is ironic as so many people who think they can cut down sleep to 4 hours and get away with it.

Bottom line: Society fundamentally misunderstands sleep.

an orangutang sleeping on the grass
Staying up late every single day human? That's Craaaazy, even we monkeys don't do that.


And I'm not the only one crying "fire!"

Even the World Health Organization (WHO) has sounded the alarm bells on sleep deprivation is a major issue for worldwide health. The WHO now warns not to expose your children under 5 to smartphones and televisions too much because it lowers their sleep quality...

Even kids are being sleep deprived today. 

And science has finally been catching on that sleep is very important the last 10 years. So let's consider how to make things better:

How to increase deep sleep

So let's consider what you can do to improve deep sleep. In the full blog post, I'll give 65 tips (ranging from most important to lesser import, so need to be overwhelmed). Here are 5 to begin with :

  1. Get morning sunlight into your eyes. Through light exposure in your eyes, sunlight tells your brain its daytime. Don't wear sunglasses or your brain won't get the impulse.

    Morning sunlight sets your "circadian rhythm" - the 24-hour day and night rhythm in your body. That rhythm works best on having light and darkness around the same time every day

    That bright light exposure during the day builds sleep quality at night...

  2. Get some afternoon sunlight exposure as well. 

    Afternoon sunlight exposure builds vitamin D - if the sun is high up the sky.

    Many people have low vitamin D levels today. Unfortunately, popping a few vitamin D pills won't fully solve the problem. Vitamin D supplements don't have all the benefits of sunlight exposure. 

    Your vitamin D status is very closely interrelated with sleep quality though. With low vitamin D levels you lose out on deep sleep.

  3. Get to bed the same time every day. Remember your rhythm likes stability? If you're going to bed 11 AM one evening, and 3 AM the next, you're jet lagging yourself.

    Yes, really.

    And recall that the more stability you create in your rhythm, the better sleep quality will be. Make sure to go to bed at the same time during weekends as well. 

    8 hours of sleep at the same time every day is far more effective than 8 hours at different time periods.

  4. Wear blue blocking glasses at night. Blue-blocking glasses are red-tinted, which prevents blue and green light from entering your eyes after sunset. Blue and green light suppress a hormone called "melatonin", which you need to fall asleep quickly, stay asleep, and... have lots of deep sleep.

    With these glasses you'll build up massive amounts of melatonin...

    The principle here is that light exposure during the day should be alternated with  darkness at night.

    Yin and yang. 

    Easy to remember.

  5. Cut down on all post-afternoon coffee or perhaps all coffee. 

    No straightforward rules can be given here though...

    Genetics, diet, and age mainly determine how coffee consumption affects your sleep.

    For some unlucky persons (like me), coffee always negatively affects sleep no matter how early it's consumed. You may be able to consume coffee in the mid-afternoon and sleep just fine though.

    The secret?


    Quit coffee for a few weeks and observe how you perform. For most people, quitting cold turkey is difficult, so wind off slowly first.

    Many people are shocked how much better they sleep after not drinking coffee for a while.

sleepy cat
Are YOU tired human? You look so small from here


The remaining 60 tips can be accessed from the table of contents below. I also explain tips 1-5 in far more detail there.

I've included both common sense strategies as well as tips your sleep coach may not have even heard off.

Other sections of this blog post describe the devastating effects of sleep deprivation and dive down into what deep sleep (and sleep in general) really is

Keep in mind that this blog post is ~30,000+ words long. If you want immediate access to strategies to improve deep sleep, jump to that specific section below. If you want to understand deep sleep better--which I highly recommend--start reading in the first section.

And you know what? 

You'll even get a surprise:

I've sprinkled some bonuses throughout the blog post that you only have access to when reading the entire thing...

No excuses allowed.



1. Introduction: Unfolding The Mystery Of Sleep
2. What Is Deep Sleep And Why Does It Matter?
3. The Sleep Deprivation And Sleep Disorder Pandemic
4. Sleep Deprivation Health Effects - 15 Avoidable Detriments:

1. Lowers immune system functioning
2. Increases your risk for certain cancers
3. Makes you more prone to get Alzheimer's disease
4. Decreases self-control
5. Makes you overweight while increasing diabetes risk

6. Decreases lifespan
7. May disrupt the gut microbiome
8. Decreases high-level thinking skills
9. Makes you less happy and (sometimes) more prone to be depressed
10. Increases anxiety risk and intensity

11. Boosts heart health risks such as heart attacks and strokes
12. Exercise performance takes a hit
13. Decreases hormonal health
14. Makes your skin look terrible
15. Increases risk for psychiatric illness

5. How To Increase Deep Sleep - 65 Better Sleep Tips

1. Watch the sunrise every day
2. Get afternoon sunlight exposure
3. Get to bed the same time every day
4. Wear blue blocking glasses during the evening
5. Quit shift work as soon as you can

6. Manage your coffee intake (wisely)
7. Supplement with magnesium and zinc
8. Make your bedroom completely dark
9. De-stress using meditation, socializing, or other relaxing activities.
10. Kill acute stress as soon as possible

11. Reduce non-native EMF exposure 
12. Get a magnetico sleep pad
13. Ground during the day
14. Tape your mouth
15. Use a healthy mattress

16. Optimize the bedroom temperature
17. Exercise - but not too late
18. Avoid late night eating
19. Manage air quality
20. Deal with noise pollution

21. Take your chronotype into account
22. Inclined bed therapy
23. Have a life's purpose
24. Keep a happiness journal
25. Socialize or cuddle

26. Get out of bed if you cannot sleep
27. Drink alcohol - during the daytime
28. Don't have sex very late at night
29. No pets (or partner!) in the bedroom
30. Wear the right clothing

31. Sleep on your side or back
32. Add the right proteins to your diet
33. Cut out excessive "polyunsaturated fatty acids"
34. Quit napping - or optimize napping
35. Avoid consuming nicotine in the evening

36. Use CBD oil for relaxation and pain control
37. Reset your sleep cycle if all else fails
38. Stretch, do yoga, or play with your pets
39. Avoid or reverse obesity
40. Quit drinking too much fluids before bed

41. Get a weighted blanket to feel safer
42. Curb excessive inflammation
43. Eat sufficient seafood
44. Use phosphatidylserine to counter acute stress
45. Reprogram your mind around being in bed

46. Listen to relaxing music
47. Improve gut function
48. Get a massage
49. Use an acupressure mat - especially to counter pain
50. Deal with trauma such as Post Traumatic Stress Disorder (PTSD)

51. Simulate rocking motions with sound
52. Use "Pulsed Electromagnetic Fields" - or PEMF
53. Curb your allergies if you cannot breathe during sleep 
54. Use cognitive behavioral therapy
55. Ventilate the bedroom to remove CO2

56. Don't use an alarm clock
57. Fix your thyroid
58. Wind down before you go to bed
59. Supplement with theanine
60. Consume adaptogens to lower stress

61. Use cyproheptadine to counter nightmares
62. Include enough calcium and potassium in your diet
63. Ensure you're not iron deficient
64. Try valerian and passionflower
65. Transcranial Direct Current Stimulation (TDCS)

6. Conclusion: Sleep - Just As Important As Food And Exercise.



Save to Pinterest:

 cover photo of this blog post about deep sleep, with a sleeping dog as a metaphor

*Post can contain affiliate links. Read my affiliate, medical, and privacy disclosure for more information.

Author: Bart Wolbers. Bart finished degrees in Physical Therapy (B), Philosophy (BA and MA), Philosophy of Science and Technology (MS - Cum Laude), and Clinical Health Science (MS).


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How many times have you heard the following:

"I sleep very well - I've slept until 11 AM on Sunday!"

"I don't need more than 5 hours of sleep a night"

"I'll sleep when I'm dead. Sleep is for losers. I'm productive so I cut down on rest."

"Tired? I'll drink a can of coffee and I'm fine. Tiredness is all in your mind"

"I can sleep anywhere I want"

"I could even sleep during the early morning:"

Well, I've got bad news for you: All of these instances are misplaced and a sign you're sleeping poorly.

And the buck doesn't stop there...

Other signs of sleeping poorly are:

  • Easily sleeping after lunch or dinner
  • Dozing off when watching television
  • Taking a couple of hours to get started in the morning
  • Afternoon dips
  • A need to randomly nap
  • Having to sleep in during the weekend

And on and on...

The natural question that emerges is of course why you'd want to spend time sleeping anyway. I mean, you're probably working 8 hours a day, spend time commuting, and need to take care of your kids and household.

With little time left the obvious action would be to cut back on sleep.

Big mistake.

Let's consider why:

Sleep in evolution

Sleep is universal across the entire animal realm. Sure, some animals sleep very little but all of them nonetheless do sleep. 

Sleep patterns do vary wildly across different species. Dolphins sleep with one part of their brain and alternate between these states. Deer only sleep a couple of hours because they're very vulnerable to predators. Horses sleep even less. 

Different types of animals also have different sleep requirements...

Herbivores - such as giraffes or elephants - generally sleep much less than carnivores such as lions or cheetahs. Lions sleep between 15 - 20 hours a day.

Humans fall somewhere in between these carnivores and herbivores, requiring 7.5 - 8.5 hours a night on average.

Every animal species thus sleeps, but do so for different lengths and in different styles. Nevertheless, the idea of sleep seems very strange from an evolutionary perspective.

Not only are you extremely vulnerable in your sleep, you also cannot spend your time to locate resources such as food or water. You can't even procreate during that time.

And yet, sleep is universally preserved across evolution. Sleep must, therefore, have an important purpose. If not, evolution would have eliminated that activity due to vulnerability.

And just to help you understand how universal sleep is: Very simple organisms such as bacteria already have circadian rhythms. The circadian rhythm is a 24-hour day and night cycle within an organism - human bodies included.

Sleep is tied to that circadian rhythm and the process of winding down may thus be billions of years old.

So let's consider human sleep - and how that sleep developed.

Human and primate sleep differences

I often talk about human evolution on this blog. The reason is that evolution yields important insights into how you and I should live today.

When your human ancestors evolved from apes a couple of million years ago, their sleep duration dramatically shortened. 

How do I know?

Simple: Modern humans have shorter sleeping times than 20+ primates.[674] 

You could even say that humans have specialized in sleep because of our capacity for intensely restorative nights.[675] Specifically, dream sleep is much denser in humans than in primates, meaning that you're able to include lots of high-quality sleep in a short period of time.

That deeper and more intense sleep drives human cognitive capacity in turn.[674; 675]

Many primates also sleep in trees and do so upright. Modern hunter-gatherers sleep like you do, on the contrary: laying down.[676] 

Over a couple of million years--when humans evolved from primates--lots has happened in sleep patterns. In fact, human brain development and sleep are probably closely tied together. That spectacular brain capacity is what most distinguishes you from your primate ancestors.

The kicker?

Modern humans have lost that ability for high-quality sleep, it seems. Let's find out why:

The advent of civilization and the beginning of sleep deprivation

Civilization has altered your sleeping pattern.


Traditional cultures arise with the sun and go to bed when it becomes colder and darker.[676] That intuition is lost in modern humans. Technology is the prime reason for that loss.

Changing sleeping patterns are like changing dietary patterns the last few centuries: 

Food has been engineered for at least 100 years, distancing you from your ancestral eating pattern. Technology has done the same for sleep by having you live inside buildings all day long and exposing you to artificial light at night.

As a result, good sleep is no longer automatically secured. 

For that reason I've begun the following undertaking:

The goal of this blog post.

In this blog post, I'll explore the topic of sleep, specifically deep sleep. Deep sleep is the period in which your body is rejuvenating, and can be contrasted with "REM" sleep - the period in which you dream.

Here I'll teach you how to maximize deep sleep.

picture of a sleeping cat
The "real" goal of this blog post: sleeping like the sleep masters.


Section 1 summary

Humans are some of the best sleepers in nature. With the change in your ancestors' environment at the dawn of civilization, sleep changed too - a trend towards sleep deprivation started. Daytime sleepiness, napping, an inability to start the day, are all examples of getting too little (quality) sleep.



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The historical perspective on sleep

Humans have always speculated about the meaning of sleep.

For thousands of years, starting with the ancient Greeks, it was believed that sleep was merely an absence of brain activity. Sleep was something that was not only useless but also irrational.

Throughout history, theories of sleep became ever more complex. These theories culminated  in Freud's analysis of the subconscious drives expressed in dreams. 

And yet, if you'd ask someone in the 1960s about sleep they'd probably tell you that it's as useless as selling sand in the Sahara.

Only later in the 20th century did scientist claim that specific neural pathways in the brain are responsible for sleep and wakefulness. Today sleep is thus envisioned as an active state--not an absence of activity.

You see, the theory you have about sleep is not without consequences...

Conceiving sleep as an absence of brain activity and as useless is dangerous as you'll likely start cutting down on it. Who needs an obsolete 8-hour period each night when time in life is already limited?

From today's scientific perspective, that conception is lunacy. In essence, the brain is highly active during sleep, albeit, in a different pattern than during wakefulness. Envisioning sleep as useless thus becomes equally stupid as seeing breathing or eating as useless.

And in the last few centuries,science has demonstrated that sleep deprivation leads to shocking health consequences - I'll treat that topic in the next two sections.

So let's explore sleep.

While oversimplifying, at least three main bodily systems regulate sleep - these are:

  1. the circadian rhythm
  2. the adenosine system
  3. wakefulness managed by "orexin"

Don't worry about the complex names. 

I'll break these names down for you if they sound difficult:

The circadian rhythm and sleep

Almost every single biological process in the human body is tied to a "circadian rhythm" - a ~24-hour cycle inside you.[183; 184]

Light in your environment is the most important influence upon that rhythm.[185-187] For millions of years, sunlight provided that stimulus for your human ancestors. 

Bright days were replaced with dark nights with campfires as your only evening light source for 365 days a year.

Today, however, artificial light is everywhere. That artificial light signals to your brain that it's daytime 24-7.

To be more precise, it's specifically the blue and green parts of the light spectrum which have that effect:

the light spectrum with ultraviolet, visible and infrared light displayed and their nanometer wavelenghts

As you can see, blue and green light are found in the visible light spectrum. Also notice that ultraviolet light (which can give you sunburns) and infrared (which makes sunlight feel hot) exist on that spectrum.

Suffice it to say that the circadian rhythm is intrinsic inside your very being. The clock inside you runs on roughly 24 hours - and the light in your environment can throw that clock off.

For that reason, the circadian rhythm needs to adapt to new circumstances after you've flown far into the Western or Eastern direction. Why? Well, after traveling East or West, your circadian rhythm is no longer in sync with the sun.

That's disconnect is called a "jet-leg" - the pattern of sunlight and your circadian rhythm are out of whack, and it takes some time for your circadian rhythm to readjust. Traveling is not the only source of jet-lag though--varying bedtimes are as well.

Your circadian rhythm is influenced through light exposure to your eyes. Those eyes are connected to a brain area called the "suprachiasmatic nucleus".[188; 189] That suprachiasmatic nucleus consequently keeps time in your brain.

And you may think:

How to know for certain that the circadian rhythm is internal to human beings?

Simple: even if you're living in a cave with no light input, your body still follows roughly a ~24-hour sleep and wake cycle.[190; 191]

And it's not just animals which have circadian rhythms though...

Circadian rhythms probably developed very early on in evolution as a mechanism for cells to change their metabolism of a changing energy reception of sunlight throughout the day.[192; 193]

Circadian rhythms have subsequently evolved throughout the ages in line with the development of ever complex life.

Sleep is directly tied to that circadian rhythm: your body expects to be awake at certain times and asleep at certain times.

If you're awake at the wrong times or asleep at the wrong times, the rhythm has a harder time staying constant. In other words, the clock inside you no longer functions properly and needs to continually re-adjust.

Disruptions in the circadian rhythm are thus responsible for losses of sleep quality - a topic I'l get back to in much more detail later on.

As I stated before, almost all (if not all) bodily processes are tied to that circadian rhythm.

Examples are the functioning of your gut bacteria,[194-196] blood pressure,[197-199] body temperature,[200; 201] cognitive performance,[202; 203] and of course sleep quality - which I'll get back to as well.

Observe how bodily processes tied to the average circadian rhythm are timed below:

the human circadian rhythm schematically displayed, with peak times of certain biological processes[226]
The circadian rhythm: notice that many biological processes are activated and deactivated at different times of the day and night.


In addition to the circadian rhythm, there's a compound called adenosine that regulates sleep: 

Adenosine and sleep

The easiest way to understand "adenosine" is through drinking a cup of coffee.

Coffee makes you less tired, right?

The reason for that finding is that coffee - specifically caffeine - blocks adenosine receptors in the brain from binding with adenosine.[204-206]

Adenosine is a compound that creates what is called "sleep pressure".[207-209] Sleep pressure is the feeling that you really need to go to sleep right now. Sleeping, in turn, causes a reduction in adenosine levels and thus reduces sleep pressure again.

Adenosine is generally low in the morning and gets higher throughout the day. If you miss a night of sleep, adenosine is still high in the morning.

The longer you stay awake, the more that sleep pressure builds up.

Your circadian rhythm, and the amount of sleep pressure that has built up through adenosine are the two main circumstances that determine how sleepy you are.

That cup of coffee thus reduces sleep pressure. There's a catch, however, in that over time your body creates more adenosine receptors so that the same amount of caffeine no longer does the trick. 


You'll no longer get that energy boost. 

And what happens if you're not using any caffeine? During the day, more and more adenosine binds to the respective receptors. Sleep pressure builds up as a result, making you more tired at 11 PM than you are at 11 AM.

Adenosine is not the only compound that regulates sleeping and waking though:

Wakefulness: orexin and other wakefulness promoters.

What's wakefulness anyway?

During wakefulness, you're receptive for both external and internal stimuli. Your own thoughts (internal) or changes in your environment (external) thus arise into your awareness. During sleep, that receptivity is decreased or absent.

Simply put, during sleep you're not conscious and in wakefulness you are.[212]

Many people are surprised to learn that sleep and wakefulness are processes that are not intrinsically tied together. 

(Some evidence to the contrary has emerged though.[211])

Several brain signaling substances are also more active during the daytime, such as adrenaline and dopamine.[229-233] Adrenaline increases arousal, while dopamine boosts motivation, goal-directed activity, abstract thought and planning.

And although I'm oversimplifying, orexin is central to wakefulness.[677-679] If the orexin system in your brain doesn't function well, you'll fall asleep even though your circadian rhythm and adenosine haven't built up too much sleep pressure.[678]

Wakefulness, from the orexin standpoint, is thus different than sleep.

(Not being able to maintain wakefulness without being sleepy can be dangerous, for instance.)

So now that you understand that different systems are responsible for promoting both sleep and wakefulness, let's dig deeper into that sleep:

Different Sleep Stages

Not all sleep is the same. Different sleep stages can be distinguished with an electroencephalogram (EEG). 

These sleep stages are central to the project treated in this blog post to increasing deep sleep quality.

So how can sleep stages be differentiated form each other?


EEG measures the electrical activity of your brain. Different sleep stages have different activity levels.[213; 214] Let's consider these stages:

  • Non-REM (NREM) stage 1 sleep. During this stage you're drowsing off but it's easy to wake you up. NREM stage 1 is the most superficial type of sleep. If you spend lots of time in NREM stage 1, your sleep quality is deemed low. If you've ever taken a 5 minute nap on the bus, you mostly spent time in stage 1 sleep. In time, however, stage 1 develops into stage 2 sleep which is paired with different EEG readings:
  • NREM stage 2 sleep. At this point, your consciousness shuts off and you're no longer (easily) awoken. A brain area called the `thalamus` actually makes other parts of your brain non-responsive to external stimuli.[215; 216; 227; 228] Most people spend the largest amount of time in stage 2, especially when they're older. The more time you spend in NREM stages 1 and 2, the lower your sleep quality is. So what you'll want instead is maximize NREM stage 3 sleep:
  • NREM stage 3 sleep. This stage consists of the star of this blog post: "deep sleep" or "slow wave sleep". The activity pattern of deep sleep emerges from the prefrontal cortex. That prefrontal cortex is the brain area located above your eyes and associated with abstract thought, self-control, and planning. From that prefrontal cortex, brain activity moves to the rear of the head when you're sleeping deeply.[222; 223] During this stage, "delta" brainwaves are active - which is why deep sleep is sometimes called "delta sleep". Delta sleep works at 0.5-4 Hz oscillations, which are the slowest. 
  • REM sleep. During this sleep stage your body is paralyzed and you're dreaming. Dreams do thus not occur during the NREM stages. Beta brainwaves are active during REM sleep - which are counterintuitively the same as during wakefulness. And while the nature of dreams is still a mystery, current science hypothesizes that they are a form of overnight therapy (among others).[181]

(Note: In the past, what is now called "NREM stage 3" was split up in NREM stages 3 and 4. These two stages have been consolidated in the newer sleep literature.)

Your body cycles between NREM and REM sleep about every 90 minutes.[220; 221] The body moves from stage 1 to 2 and 3 and back, and then hits REM sleep. That cycle is repeated 4-6 times, depending on how long you sleep.

Keep in mind that sleep is not yet perfectly understood either. Only for the past 15 years has the importance of sleep really become clear - although we're just scratching the surface.

So let's talk about how to optimize these sleep stages:

Sleep quality

"Sleep efficiency" is one frequently used metric for sleep quality. Sleep efficiency is the time you spend sleeping divided by the time you spend in bed. 

Low sleep efficiency thus means you're laying awake in bed - which isn't great.

The time spent in NREM 3 and REM sleep is a better measurement of sleep quality though. 

Spending lots of time in both REM and deep sleep gives you that rejuvenated feel after a perfect night of sleep. The more time you spend awake in your bed, or in sleep stage 1 and 2, on the contrary, the worse your sleep quality becomes.

You'll thus want to maximize sleep efficiency, NREM 3, and dream sleep. So let's consider what these sleep stages are good for:

"Slow wave sleep" or "deep sleep" function 

The effects of deep sleep are all encompassing on your health...

Deep sleep is very important in memory formation, for instance. During deep sleep, information moves from your short term into long term memory.[680; 681] Without that long term memory you can't remember anything you learn or things that happened 2 weeks ago.

During deep sleep your body also recovers.[682] Growth hormone is released during slow wave sleep.[683; 684] That growth hormone helps cells throughout your body regenerate, 

And while excess growth hormone levels are dangerous, declines are probably sub-optimal as well - and associated with lower deep sleep quantities. 

But there's more:

Brain cells called "glial cells" - important for regenerating "myelin" which speeds up nerve conductivity - are also restored during this sleep stage.[686] Glial cells are part of astrocytes, which have a repair and nutritional function to the neurons - your main brain cells.

During slow wave sleep your "glymphatic system" is also more active.[687] That glymphatic system is aptly called the brain's "waste removal system".[688; 690] In animal studies, it's also been demonstrated that the glymphatic system allows for the delivery of nutrients.[689] 

Additionally, brain cells communicate with each other during deep sleep. Connections between brain cells are strengthened so that what you've learned becomes internalized.[691-693]

So while the function of slow wave sleep used to be an enigma 15 years ago, the mystery is slowly uncovered. As you can see, that type is sleep is hugely important for many bodily and mental processes.

For completion sake, let's also quickly consider REM sleep as well:

REM sleep benefits

REM sleep is more like wakefulness with very chaotic brain wave patterns. REM has no voluntary muscle involvement. Not all animals have REM sleep - REM has only developed later in evolution.[252-254]

NREM sleep is thus far more universal than REM sleep.

REM has many functions, such as helping form memories,[255-257] boosting creativity,[258; 259] aiding in metabolic rate,[260; 261] emotional processing,[180-182] and keeping your organs healthy.

REM also plays a major role in emotional recognition. In fact, REM sleep may be responsible for many of the uniquely human traits that I've described in my blog post on dopamine.

Dopamine is not only responsible for making you motivated, assertive, and happy, but also plays a role in uniquely human capacities such as abstract thought and complex planning. 

That REM sleep takes place mostly later in the night.

So if you're going to bed really early and wake up really early, you will lose out on a disproportional part of REM sleep (and probably get more deep sleep). With late bed and wake-up times, the opposite is true. 

There's some bad news though:

Sleep quality declines with age. Let's take a closer look at that dynamic: 

Sleep with aging

Let me start with an analogy:

I've often taken children as the paradigm of health on this blog. Children have superior metabolisms, for example, because they automatically burn many calories without having to do anything to accomplish that feat.

As you age, you burn fewer and fewer calories at rest, setting you up for weight gain starting in your 20s and 30s.

Sleep shows a similar pattern throughout aging. And unfortunately, deep sleep is most impacted during aging.[217-219] 

By the time you're 70 years old, about 80% of slow wave sleep is gone. Awakenings during the night also become more frequent. REM sleep remains more intact, fortunately.

Now you also understand why this sleeping blog is so important - you'll want to prevent deep sleep declines with age as much as possible.

Your brain itself is negatively affected by aging as well. When you become older you'll frequently experience a decline in the size and health of the prefrontal cortex.[224; 225] Remember that the electrical pattern of deep sleep is initiated from that prefrontal cortex, so the decline in that brain size may explain why slow wave sleep decreases with aging.[223]

Other problems with aging are that you're more easily wake due to sensory experiences, take longer to fall asleep, sleep shorter overall, and have shorter sleep cycles.[234-237]

If you want to avoid decreased sleep quality when getting older, make sure to avoid modern diseases such as diabetes and Alzheimer's.[238-242] All these modern diseases are tied to declines in deep sleep quality.

Implementing a healthy lifestyle can prevent some of the declines in sleep quality with aging - as some elderly people experience larger decreases in deep sleep than others.[243]

If not, then both deep sleep quantity and quality already decline from your 20s and all the way into middle age.[245; 246] That quality is called "slow wave activity".[246-249] So not only does deep sleep quantity go down, the quality of the brain activation pattern also deceases.

Men generally have much bigger declines in slow wave sleep quality and quantity than women.[251]

The solution?

Easier said than done:

Make yourself younger. Start sleeping like a kid. 

Don't sleep like a baby though. A toddler is a better example to follow because they have an entrained circadian rhythm--babies don't...

And in terms of sleep, elderly people are the direct opposite of young ones:

Teenagers and sleep

Teenagers have different sleep patterns than younger children and adults. 

Usually, teenagers love to stay in bed until late in the morning. And in fact, there's a good reason for that.

Teenagers are frequently "night owls" - their sleep cycle is moved forward to the night.[695-697] For that reason, most teenagers won't perform at their best early morning and may experience their peak awakening moments around early afternoon.

Teenagers also have less REM sleep than kids and transition towards more deep sleep dominance. Nonetheless, teenagers still need lots of sleep at their age. 9-10 hours a night is probably optimal if you're 18 years old.

After your teenage years, you'll often transition towards being more of a morning person. And as an adult, the real decades of sleep deprivation subsequently begin. 

So let's move on to a question that's probably on your mind right now:

How much sleep you really need.

Sleep needs vary throughout age. Newborns need to sleep up to 17 hours a day - often they sleep chaotically. From 4 months to 2 years of age, up to 15 hours of sleep are recommended.

Sleep hours then slowly drop to about 11 hours until you're 12 years old.

Teenagers subsequently need about 9-10 hours of sleep. After your teenage years, you need about 6-9 hours of sleep, independent of age.

I disagree with lots of other sources that state that elderly people need less sleep. The fact is that lots of elderly people sleep less but that doesn't entail they need less sleep. Elderly people may in fact need more sleep because they're sleep quality has often come down.

How much sleep you require also depends on the person - recall that some people naturally need more sleep than others.[250] Chances that you're among the lucky people who need 4 hours of sleep are very slim though.


Many people who sleep very little and assume they don't need more sleep are thus chronically sleep deprived.

If your sleep quality is high, I recommend a minimum of 6 hours of sleep. I do tend to think that more quantity and quality of sleep is better. I know one person who experiences 4 hours of deep sleep and 2 hours of REM sleep each night, which is impossible if you're only sleeping 6 hours.


Some time is always allocated to NREM stages 1 and 2 - these stages cannot be eliminated. With 6 hours of total sleep, you'll miss out on maximizing deep sleep and REM sleep.

(That person - a she - should start a new Olympic sport: "sleep sports". She'll win gold medals time and time again...) 

So 7-8 hours probably confers maximum benefits. 6 hours can be optimal, depending on your circumstances.

And that's it...

All you need to know about the basics of (deep) sleep. In the next section, I'll consider the topic of (omnipresent) sleep deprivation.

Section 2 summary

Different systems such as the circadian rhythm, adenosine, and orexin all manage your sleep and wake cycle. Optimizing these systems promotes deep sleep. You need deep sleep for full-body rejuvenation and brain function. The amount of deep sleep you get declines with age - preventing that decline and improving deep sleep is thus the goal in this blog post. 



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another picture of a sleeping cat
"I'll sleep when I'm dead" - said no cat ever... 


This section is a bit depressing because it showcases a devastating sleep deprivation epidemic. Sleep disorders, which are more common than you'd think, also contribute to that problem.

So let's get started the right way...

A shocker:

Sleep deprivation statistics

1 in 3 Americans, on average, is not getting 7 hours of sleep a night .[210] That means that 1 in 3 Americans are chronically sleep deprived.

On average, people are getting about 6.5 hours of sleep each night. And sure: If these 6.5 hours had high quality, there would be less of a problem. 

But due to damaging habits such as technology use in the bedroom, however, different sleeping times across the week and coffee drinking in the evening, quality isn't nearly what it should be either.

And that's a shame...

So just sleeping more is thus not the answer.

(You'll find many reasons why that's the case later on in this blog post.)

People are spending tons of money on getting better sleep though:

40 billion dollars a year are spent on sleep improvement.[694] That number stems from 2015 and is projected to grow to ~50 billion next year (2020). With the possibilities to increase deep sleep, I wouldn't be surprised if the sleep improvement industry grew dramatically to $75 billion in 2025.

Sleeping is hot, and with good reason:

Besides the 1 in 3 people who is chronically sleep deprived, another third is probably not hitting high deep sleep percentages. Many people thus do "OK" in the sleep department, instead of doing great.

That average quality sleep may be even more dangerous than poor quality. 


Let me explain:

With complete sleep deprivation at least you know your health is deteriorating. With average sleep quality, you're often not realizing you can do better in the first place. And yet, great sleep probably has massive advantages over average in the long run.

Fortunately, the tide is turning in society's conception of sleep. 

For instance, Silicon Valley companies now allocate workspace to areas in which you can meditate or sleep. Flexible work schedules have become a possibility - a blessing to morning birds and night owls.

Fixing just adult's sleep misses the point though. More action is needed:

It's not just adults who are getting hammered by sleep deprivation. The teenage sleep problem may be far worse for several reasons:

  • Teenagers are only sleeping 5-7 hours during school days even though they need 9-10 hours of sleep. Comparison? An adult who gets 5 hours of sleep while needing 6-7 hours of sleep only has a 1-2 hour deficit. For a teenager that's 3-5 hour.
  • Teenage brains are still developing. That development continues into your early (and perhaps even late) 20s. Sleep is thus probably more vital at that time than during your adult years, even though teenagers are massively missing out.
  • Even more worrisome is that society is not adjusted to the sleep schedule of teenagers. Remember that most teenagers are night owls, even though they're required to go be at school at 8 AM. 10 AM would be a far better starting time for this age group.

And how about children?

At least these poor minors are getting what they need, right?

Children, unfortunately, are also sleep deprived.

And that problem is even getting worse.[698] Children between 6 and 12 years old are missing out anywhere between 1 and a whopping 5 hours of sleep each and every single school night.


So really parents, if you cannot take care of your children then don't take them. Giving kids too little sleep is not done (read the next section why).

I'm not a parent myself, so I cannot tell you what you should do to be a good parent. But it's glaringly obvious what you shouldn't do.

Lifestyle - including technology use - is the most important reason for poor sleep in children. And as parents, you've got full control over that lifestyle. If your kid cannot be happy without screens, (s)he is addicted. And if that school caused the problem, you're responsible for picking another school.

If not, you've got work to do...

Either way, technology kills sleep even more in children than adults because they're more susceptible to addiction. Children's eyes are less protected against the bright light, and kids don't have the brain development to self-regulate themselves as well as adults yet.


The problem gets worse though...

All of the undersleeping during school and work days builds up sleep debt:

The problem of sleep debt

Say you skip a night's sleep one day. The next day you sleep 6 hours. And the following two nights you're in bed for 11 hours to make up.

Alternatively, you could have slept 7 hours a night for 4 days straight.  

Under both scenarios, you'd have a total of 28 hours of sleep spread over 4 nights.

The kicker?

Sleep quality is way better during the second instance. 


Simple: even though the deep and REM sleep phases will be proportionally more predominant during the 11 hour nights, they do not compensate for the loss of the 0 and 6 hour sleep times. You accumulate what is called "sleep debt" as a consequence.

And like government debt sleep debt will also never be repaid.

Just see sleep debt this way: 

Say you smoke cigarettes for 5 days a week and then quit on the weekends. In that case, your lungs will be in a poorer condition than if you didn't smoke at all. Poor sleep thus always damages your health.

It's not just sleep quantity that matters though. An even biggest issue with getting adequate sleep quality are sleep disorders.

The story gets even worse before it gets better. So fasten your seat belt once again:

Sleep disorders

About 50 - 70 million Americans currently have a sleep disorder that prevents them form attaining quality sleep at night.[210] That's a whopping 1 in 6 people.

Sleep disorders including insomnia, sleep apnea, restless legs, and narcolepsy, all lower sleep quality. Let's go over these conditions one by one:

  • Insomnia is the inability to sleep, even though you're tired. You thus want to sleep and "should" be asleep.[631-633] The result of insomnia is excessive daytime tiredness. And you know what? A whopping 10-15% of the population suffers from insomnia.[632] Different types of insomnia exist, such as not being able to sleep due to psychological reasons (conditioned non-sleeping), insomnia as a side-effect of a condition such as depression, and insomnia as a side-effect of medication. 
  • Sleep apnea denotes frequently waking up during the night because of an inability to breathe properly.[634-636] As a result of shortness of breath, the body enters a "fight or flight" response which wakes you up many times per night. Waking up so frequently leads to fragmented sleep, a sign of low-quality sleep. Different causes for sleep apnea exist, such as narrowing or collapsing airways.[635] Different causes also require different treatment.[635] Another crazy statistic? 24% of men and 9% of women have their sleep impaired by sleep apnea.[641]
  • Restless legs is a condition in which you feel like you should be moving your lower legs.[637-640] The condition is also associated with pain and unease. Moving cures that unease, but you cannot sleep while you're moving. Restless legs thus keeps you from sleeping properly. About 3% of adults suffer from restless legs syndrome.[638]
  • Narcolepsy is a condition in which you fall asleep during the daytime.[642-644] Technically, it's not a sleeping condition but a problem in maintaining wakefulness. As a result of narcolepsy you'll be falling asleep during the day - doing so can be dangerous while driving or operating machinery.[643] Such sleepiness is often paired with muscle weakness, making the condition very dangerous. Fortunately, only up to 0.2% of the population in developed countries suffers from this condition. During narcolepsy, the orexin system that promotes wakefulness malfunctions.[678] Recall that I treated orexin in the previous section. Moving on:
  • Hypersomnia or sleeping too much.[645-647] Some people sleep 12 hours a day, which can lower your overall health. Although the reason for hypersomnia is sometimes unclear, the condition is affected by lifestyle choices.[645] Hypersomnia may overlap with narcolepsy in some cases.[647] One more condition to consider though:
  • Parasomnia, or altered sleep, is the last sleep condition I'm considering here.[648-650] A sleep paralysis, in which you're awake but cannot move your body, or sleepwalking are examples of parasomnias. You can also experience dreams at the wrong moments in time, such as when falling asleep or when awaking. Sleep terrors are another example, as well is sleep sex. Yes, sleep sex really exists...

If you've got a condition such as sleep apnea or narcolepsy then make an appointment with your physician.

This guide is not meant to manage or treat these conditions, although many of the later tips for deep sleep will improve your sleep quality almost regardless of your sleep condition.

And it's not just sleeping conditions that lead to deterioration in health:

Reversely, many health conditions affect your sleep quality. Let's look at a few conditions and observe their effect:

  • Chronic pain, unsurprisingly, has a huge effect on sleep quality. With chronic pain, you'll take longer to fall asleep, wake up during the night, and sleep less in total.[651] The more pain you have, and the more places that pain is located, the greater the sleep disturbance.[652] As a result, about 25% of people with chronic pain experience insomnia all the time.[653] Depression and ruminating about worst possible outcomes in your life trajectory are associated with worse sleep outcomes.[654] 
  • PTSD, or "Post-Traumatic Stress Disorder", is a condition in which your brain continually produces a fight and flight response. Sleep disturbances are the result of PTSD.[177-179; 547-549] Anxiety, hyper-vigilance, and nightmares are characteristics of PTSD. 
  • Autoimmune conditions such as Parkinson's and Multiple sclerosis. In Parkinson's, brain cells associated with dopamine creation lose function. The result is moderate to severe sleep disturbances.[655] Daytime sleepiness is the result of these disturbances.[656] Multiple sclerosis - in which the conductive sheet in the nervous system degenerates - is also paired with sleep problems.[657; 658] Insomnia, daytime sleepiness, and waking up due to involuntary movements are the result.[657]
  • Lung diseases, such as Chronic Obstructive Pulmonary Disease (COPD) are paired with both insomnia and sleep apnea.[659; 660] The reason is that lung function declines, allowing for poorer respiration during the night. Breathing problems are frequently worst during the nighttime, for the simple reason that you're laying horizontal instead of having a vertical posture. Asthma is similar and also paired with lowered breathing capacity.[661]
  • Heartburn increases when you're prone as well. In that position, stomach acid most easily enters the esophagus. If you've got heartburn problems, there's about an 80% chance that heartburn causes trouble during the night.[662] About 20% of people experience heartburn weekly.[663]

As you can see, many health conditions can cause problems in sleep quality - leading to further health deterioration.

Lowered sleep quality in these conditions doesn't mean you're helpless--instead, it means you need to double down on improving the amount of deep and REM sleep you get.

in section 5 I will give suggestions to cope with some conditions that deteriorate sleep, such as chronic pain and PTSD.

In the next section, I'll consider the problem sleep deprivation has in causing health deterioration. Poor sleep thus causes disease, and disease further makes your health come down.

a bedroom that's filled with sunlight in the morning
The time you spent in your bedroom is just as important as the time you spend in the kitchen.


Section 3 summary:  

Sleep conditions are more prevalent than you'd think and cause a deterioration in sleep quality. Once you get a chronic health condition, such as heart failure or cancer, you'll generally also lower your sleep quality. Many people are also chronically sleep deprived in today's society. 


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I've often talked about the "poison drip" on this blog post. The poison drip is an almost imperceptible source of damage that wreaks havoc on your health over time.

Air pollution is one example of a poison drip - many people breathe polluted air while never consciously being aware they increase their risk for heart disease, Alzheimer's, diabetes, and lung cancer.

Sleep deprivation is another poison drip. Why? Well, many people are so sleep deprived in today's society that they've never even felt the difference between great sleep and a continuous state of sleep deprivation. 


Only after you've fully optimized your sleep will you realize how sleep deprived you were for a long time.

I realized that effect myself in 2014 when I installed an app on my computer to reduce blue light emissions. I immediately became sleepy and realized I just found a game changer - but I also realized that something in my environment has lowered my sleep quality for most of my life.

Sad but true...

This section considers 15 different health effects of sleep deprivation are considered. The goal of showing you all these effects is to demonstrate that optimizing sleep quality is non-negotiable. 

So let's get started: 


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1. Lowers immune system functioning

Had a bad night of sleep?

The first thing impacted will be your immune system.[1-3] 

Inflammation, which is closely intertwined with immune system functioning, is raised after sleep loss for example.[1; 6] In fact, sleep deprivation has similar effects upon inflammation as if you were alcoholic or depressed.[1] 

Inflammation is chronically raised in many modern conditions such as cancer and diabetes.[4; 5] 

The solution?

Over the long term, you'll want to keep your inflammation levels down. 

The effects of sleep loss go beyond inflammation though. Poor sleep also makes you more susceptible to a common cold, for example.[3] 

The immune system is even directly dependent on your circadian rhythm because it is (or should be) more active during later in the day and less so late at night.[7] That immune system is also regulated sleep itself by making you rest when you're hit with an infection.[8; 9]

So mom and grandma were right: get your sleep if you want to stay strong.


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2. Increases your risk for certain cancers

Another shocker for a sleep-deprived society:

In women, the risk for breast, ovarian, and uteral cancer increases.[10-13] For men, unfortunately, an increased risk of prostate cancer may exist.[15-18]

Gastrointestinal cancers also increase with excessively short sleep duration.[21-25] Shift work heightens that risk, simply because it leads to circadian disruptions 24-7.[25]

Additionally, if you've got sleep issues, such as sleep apnea, poor sleep quality, or insomnia, cancer risk directly goes up.[14]

In fact, sleep deprivation directly fuels tumor growth in rat studies.[19; 20] Sleep fragmentation - i.e. waking up frequently during the night - is also responsible for that growth.[20]

Even if you're so unfortunate to be struck by cancer, improving sleep quality may lead to a better prognosis over time.[25; 26]

Sorry about the depressing findings...

But remember: It's never too late to start sleeping better... 


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3. Makes you more prone to get Alzheimer's disease

Remember the mentality of world leaders in the 80s? Both Ronald Reagan and Margaret Thatcher prided themselves on their ability to get by on 4 hours of sleep.

Elon Musk is even worse today - with his so-called "120-hour work weeks". 120 hour work weeks leave 48 hours for sleep, which is a bit under 7 hours at the maximum.

But as Elon needs time for other activities such as seeing his kids, traveling to work, showering, and socializing, not much time is left for sleeping.

His stress levels are so high that he needs "Ambien" to falll alseep - a prescritpion drug that knocks you out.

The end result is making many very stupid strategic errors in the last years, such as:

  • Saying he had "funding secured" so that Tesla could be taken private. No funding was secured, however.
  • Calling a guy in Thailand a pedophile, and doubling (and tripling) down on that claim. That issue has turned into a lawsuit because there's no evidence the guy is a pedophile.
  • Rage firing employees while having other talented staff leave the company.
  • Frequently getting angry at reporters and Tesla shareholders for asking the "wrong" questions.

Please Elon, sleep more and you'll be an even more productive person (and save your company from bankruptcy!) 

All these aforementioned actions are signs of deteriorating brain function under sleep deprivation.

Unfortunately, sleep loss also directly causes brain diseases such as Alzheimer's. In fact, both the aforementioned Reagan and Thatcher developed Alzheimer's in their later years.


Perhaps not:

Several plaque proteins such as "beta-amyloid" and "tau proteins" prevent brain cells from communicating in Alzheimer's also increase in quantity with sleep deprivation.[27; 28]

That plaque, in turn, decreases sleep quality by itself.[28] In a sense, a vicious cycle of sleep deterioration is thus begun due to plaque formation.[30; 31]

In plain English, Alzheimer's deteriorates your brain condition and sleep deprivation has everything to do with causing that problem. 



Even one night of sleep deprivation already causes a buildup of plaques in the brain by 25-30%.[32; 33] And the more sleep deprived you are, the quicker the (precondition to the) disease progresses.[34-36]

But there's good news:

Good quality sleep assists in removing excessive plaques from the brain.[29] Sleeping less thus only creates the illusion that you have more time. 

funny looking dog who is laying on his back, used in the context of a joke
Trying to intentionally sleep less than 6 hours? That's crazy human!


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4. Decreases self-control

Remember that time you skipped a night of sleep or when you just slept very poorly?

I do.

One of the first capacities to suffer is your ability for self-control. You'll be acting more impulsively and you'll have a decreased capacity for keeping your focus.[37]

Decision-making quality also takes a hit.[37] 

The results regarding self-control are far-reaching. You're more prone to engage in criminal behavior if you're sleep deprived, for example.[38] That risk of engaging in crime is directly explainable through a sleep loss-induced decrease in self-control.[38]

Want to get some work done? Sleep deprivation undermines your capacity to keep your attention on the task and increases procrastination.[39] 

The only downside of the studies I've been citing is that they're mostly associative studies--no direct causal role can be posited (yet).[37-39]

And to be very clear: you don't need to skip a night or two to become an impulsive wreck. Even minor sleep losses like getting 6 hours of sleep a few nights in a row instead of 7 or 8 already decrease self-control.[40]

Sleep loss leads to all kinds of "depravities", such as:

  • Overeating.[41-44] A brain area involved with emotions called the "amygdala" increases in activity--the prefrontal cortex located above your eyes which is responsible for self-control, among others, is inhibited.[41]

    Simply put, you'll desire more high calorie (processed) foods. Binge eating also likely increases with poorer sleep.[42] Snacking behavior also goes up, and snacking is rarely healthy.[43]

  • Increased risk of causing car accidents.[45] The research on this topic is very clear, unfortunately.

    Sleeping 6 hours per night increases car crash risk by 33%.[45] Young drivers perform worst when sleep deprived - also because they are less able to tolerate sleep deprivation.[46]

    The problem gets worse though:

    Very poor sleep over a period of months triples car accident risk.[52]

    Up to 20% of all serious accidents may be explainable through insufficient sleep alone.[47]  Many of these accidents are caused by what are called "micro-sleeps".[48] Microsleeps cause you to dip into sleep for a few seconds, which is just long enough to cause an accident.

    What's even worse is that no signs exist to warn you of these microsleeps.[48] You can't even consciously remember these moments after the fact.[48]

    And here's what is really dangerous:

    Sleep loss is about as bad as having a few glasses of alcohol and driving.[51] And having a few drinks further increases the risk of sleep deprived driving - which frequently happens during the evening.[49; 50]

    2 drinks thus equals 5 drinks during sleep deprivation, and mirrors drunk driving.

  • Engaging in more risky behavior - for some people.[53] The list of depravities continues. 

    If sleep loss is voluntary - i.e. you choose to sleep only 5 hours instead of 8 - then you're going to drink more alcohol, be more dis-inhibited, and engage in more dangerous driving.[53]

    Adolescents, who generally already are more risk tolerant than adults, takes that trait over the top during sleep deprivation.[54; 55]

  • Makes you (more) immoral. Sleep deprivation also brings up the worst in human beings. Discriminatory tendencies go up, for example.[56]

    Additionally, you're unable to recognize emotions in other human beings and almost certainly you're more driven by anger.[57-60] The brain parts engaged in self control can no longer adequately control lower more emotional brain parts in that instance.[59]

  • Committing violence.[61-62] Yes, really. 

    Of course, most people will not become violent after missing a night of sleep. But in others, in which the threshold for violence is already lowered, risk increases.


So yes, sleep deprivation brings up the worst in you. 

And what's even worse?

You may not even consciously perceive how toxic your behavior becomes if you're sleep deprived. Why? Many people counterfactually rate themselves as functioning reasonably well even though they don't after poor sleep.[63; 64]

Now you begin to understand why I said that most people need to experience high-quality sleep first, before realizing they were sleep deprived for a long time.

Moving on to another big problem:


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5. Makes you overweight while increasing diabetes risk

Sure, I've talked about sleep deprivation increasing your risk of making poor food choices and overeating.

But will you get overweight and sick because of that behavior? You're only overeating once, right? Next Monday you'll be eating healthy again, so there's no problem.

Not so quick...

Very few people miss just one night of quality sleep. And not only will these people be continually at risk of eating too much of the wrong foods, the way their body processes these foods is also negatively affected.

Sleep deprivation is strongly associated with diabetes, for example.[65] The question then becomes: what's first, the sleep deprivation or diabetes?

The answer is the former - although it's not just sleep deprivation causing diabetes, of course.[66; 67] The case can nonetheless be made that sleep deprivation contributes to diabetes.

Blood sugar levels will get dis-regulated with sleep loss, for example.[66] The reason for that finding is that carbohydrates (such as glucose) are more prone to stay in the bloodstream while not being taken up by your cells with poor sleep.[67] 

Appetite also increases, as you already know.[68; 70] 

Even kids are affected by the trend of sleeping less, increasing their obesity risk.[76; 77] Sad but true, once again...

Bottom line? A greater risk for obesity and diabetes.[69; 71-75]


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6. Decreased lifespan.

I'm often talking about "all-cause mortality" on this blog. All-cause mortality is an aggregate of all possible risks of dying. In essence, your risk of dying of a heart attack, a car accident, and old age are all included in that metric.

Having a short sleep duration increases that mortality metric with 12%, while (excessively) long sleep is associated with a 30% risk increase.[78; 79; 81] Some caveats do exist with these studies though, including the fact that they often depend on surveys which are commonly inaccurate.[80]

The most interesting finding to me is that sleeping very long is consistently associated with poorer health outcomes.[82; 84] Those outcomes almost certainly lead to decreased lifespan.

Overall health and inflammation may also determine how destructive short or long sleep duration are.[83] So if you're only sleeping 6 hours a night but you're otherwise in excellent health, there's less to worry about.

And the journey through "inferno" continues:


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7. May disrupt the gut microbiome

Your circadian rhythm plays a tremendously important role in the gut microbiome - the mass of bacteria found in your gut.

These bacteria can even alter your circadian rhythm in turn.[85-87] The reverse is also true: circadian disturbances affect the gut microbiome.

In rat studies, sleep disturbances lead to alterations in bacteria populating the gut that are not positive.[88] Human studies exhibit the same findings.[89] The end result is that your body processes carbohydrates differently, for example, leading to higher blood sugar levels with sleep deprivation.

Much more research is needed to research this connection in more detail though. I'll be waiting impatiently on those results.

Moving on:


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8. Decreases high-level thinking skills

Sure, I've previously mentioned that sleep loss causes a decrease in attention span. The problem gets worse though - many brain functions are affected:

Such thinking skills include creativity, memory, and abstract thinking. Let's consider these one by one:

Creativity and abstract thought

Higher-order human thinking skills such as creativity and abstract thought are negatively impacted.[91; 92]

As a result, you'll less likely think outside the box.[91] With a lower ability to think outside the box your problem-solving ability is adversely affected.

The simpler the task, the less it is impacted by sleep deprivation. Routine jobs thus remain doable, while complex work becomes more and more difficult. Unfortunately, it's complex high-level thinking skills that pay well in today's society, not routine work.

Working memory

Additionally, working memory is also negatively affected by sleep deprivation.[92] Working memory denotes your brain's ability to keep multiple pieces of information in the back of your head at the same time - a 10-digit phone number is an example.

Poor sleep simply allows you to remember fewer digits or visual objects in that working memory.[93-95] Filtering out incorrect information (ignoring distractions) becomes more difficult as well.[95]

What's even worse is that your full working memory only recovers only a few days after losing a few hours of sleep.[93]

Spatial and emotional working memory is also reduced, although the former is only studied in mice.[96; 97] Spatial memory consists of your ability to remember the place of objects in space, and emotional working memory is your ability to ignore emotional distractions (such as angry faces).

Sleeping well has the opposite effect: you'll make quicker improvements when training your working memory.[98]

Long-term memory formation

Remember that both deep and REM sleep are needed for memory formation? 

Well without high-quality sleep your long-term memory takes a hit. A brain area called the "hippocampus" is responsible for that effect.[99-101]

Sleep depriving mice causes memories not to consolidate in the brain.[102] Younger mice experience a bigger memory-inhibiting effect than older ones.

A simple analogy to understand that inability to form memories is the idea of a hard drive. If you don't save a Word file on your computer, you won't be able to access it later.

So if you study for an exam and memories don't consolidate due to poor sleep, you won't remember what you've attempted to cram into your head.[104-108]

All your efforts down the drain...

Other cognitive domains, such as "processing speed", are also negatively affected under sleep deprivation.

Processing speed is a simple measurement of how quickly your brain works. With sleep deprivation, your brain will simply work slower - just like getting a downgrade on computer speed.[109]

Bottom line: Sleep well to think well. Andd then thee's this other brain-related area:


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9. Makes you less happy and (sometimes) more prone to be depressed

woman who wakes up in the morning and opens the windows for sunlight to come inSerenity: how every morning ought to look like.

Feel like crap?

Maybe you've been chronically undersleeping. 

To be clear, an association exists between lower subjective well being and abnormal sleeping patterns (either long or short).[110; 111; 113] Good sleep, on the contrary, leaves you more satisfied.[112] 

A very strong argument can be made that poor sleep makes you less happy - an observation that can be verified by almost anyone.

The relationship between depression and sleep deprivation is more complex though, as sleep loss is also a symptom of depression.[114-118] In that case, it's harder to tell which came first, the chicken or the egg.

What's even stranger is that sleep deprivation often reduces symptoms of depression if you're depressed.[119; 120]

I don't know how to explain that finding, especially since:


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10. Increases anxiety risk and intensity

What's the difference between "stress" and "anxiety"? Many different explanations exist - I consider these definitions mostly overlapping but describe someone as "anxious" if their capacity for action is inhibited, while stress doesn't necessarily prevent you from acting.

(Most of the definitions of stress and anxiety are actually incoherent because they overlap too much.)

Sure, stress is more technical as a definition, entailing a continually present "fight, flight, freeze or faint" response.[123; 124] 

Sleep deprivation increases your anxiety levels.[122] And if you're already chronically anxious, sleep deprivation ups the ante.[121] 

Animal studies, surprisingly, show the opposite effect.[122] One reason may be that you're less inhibited under sleep deprivation...

Next, another problem you'd do well to avoid:


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11. Boosts heart health risks such as heart attacks and strokes

The story keeps getting worse...

Losing sleep increases both heart disease risk as well as the propensity for deterioration of predictors of heart disease such as high blood pressure.[125; 128; 129]

Simply put, sleep loss causes stress.[125] Levels of stress hormones such as cortisol are actually altered in that case.[126; 127] After losing sleep, your cortisol levels will be about 40% higher that night.[126]

Adrenaline levels also shoot up. Excessive adrenaline levels contribute to heart disease.[131; 132]

A part of the nervous system that's associated with the fight and flight response, called the "sympathetic nervous system",  additionally becomes more active.[130]


An increased risk of getting heart attacks and strokes. To be more precise, only strong associations exist.[134] Everyone today knows that association (or correlation) does not equal causation.

Studies that do use causal inferences posit that in women, poor sleep more than doubles the risk of strokes and heart failure - men seem less affected.[133; 136] 

Optimizing sleep quality, moreover, is also important for preventing heart and blood vessel disease.[135]

Stroke risk also increases with poorer sleep quality.[137] Both sleep disorders and sleep disturbances are the main risk factors in getting a stroke.[138; 139] Both shorter and very long sleep increases that risk.[140]

Bottom line: sleep well if you care about heart health. It's not just the loss of love that can make you "heartbroken" - sleep deprivation has similar effects.


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12. Exercise performance takes a hit

Slept for 4 hours, and now doing a quick gym workout to make you feel "awake"? 

Surprise, surprise:

With sleep deprivation you probably won't perform as well as you otherwise would.

Under sleep deprivation, exercise capacity becomes significantly lower.[141] Endurance is generally more heavily impacted than maximal strength though.[142-145]

Power output (i.e. explosive force) is usually not decreased with sleep loss, although findings are inconsistent.[157-161]

Heat and cold tolerance also go down with sleep deprivation - in fact, cold exposure is most affected.[148-151] You may be aware of that effect from an inability to stay warm after losing sleep the night before. Your ability to lose heat also goes down though, making you heat intolerant as well.[148]

So prior to an important competition, it's unwise to spend the night partying - even if you don't drink any alcohol. In such a case, lowered heat or cold tolerance can make the difference between winning and taking 4th place.

Your core temperature also becomes lower--a sign of slowing metabolism--after sleep loss.[150]

Motor control, moreover, especially fine motor control is very heavily affected by losing sleep.[151-153] Sleep loss deteriorates motor control about as much as intoxication with alcohol.[152]

Balance and stability also go down.[156] 

Without sleep, you also cannot learn new skills that depend on motor control - at least when looking at rat studies.[154] So skateboarding or surfing practice might be much more useless if you're sleeping poorly. Weight lifting and running are probably less impacted.

Overall, your body just performs poorer when sleep deprived. If you're an athlete you'd do well continuing reading this blog post to optimize your performance.

There's yet another reason to avoid being sleep deprived as an athlete though: 

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13.  Decreases hormonal health

And just when you thought things couldn't get any worse...

If you cut away a few hours of your sleep per night, testosterone levels will be about 20% lower after just one week.[162] There's also an association with impaired sleep and lower testosterone levels.[163]

A study with only a few men additionally showed that missing one night of sleep already significantly reduces testosterone levels.[164]

So there's no way out: you need to sleep (well). Keep in mind that testosterone is also important for women - being supportive of both physical and mental wellness.[164-166]

In both sexes, low testosterone will decrease your ability to recover from workouts as well as overall well being, bone health, energy, heart condition, confidence, and cognitive performance.

And just when you thought my message couldn't become more depressing: Looks also deteriorate under sleep deprivation:


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14. Makes your skin look terrible

(Don't worry, this sad section is almost over)

Dark circles under the eyes 24-7? 

Sleep deprivation may be the cause...

While unimaginable at first thought, sleep deprivation does lower skin quality. 

And as you know by now, sleep deprivation can make your immune system go haywire. That  immune system effect affects "collagen" production in the skin in turn.[167] Collagen is a protein that keeps your skin firm and elastic.

Unfortunately, sleep deprivation is not merely in the eye of the beholder. 

How do I know?

Other people, in fact, rate you as having less healthy skin when you've lost sleep.[168] The effects are shocking, as red and swollen eyes, dark circles around the eyes, pale skin with wrinkles, and a drooling mouth are all attributed to you with sleep loss.[168]

Bottom line: There's no way to hide that chronic sleep deprivation look. And to my knowledge, no makeup exists to cover up blood-shot eyes.


You appear as less attractive and people are less likely to socialize with you.[170]

Chronic sleep deprivation is also associated with quicker skin aging.[169; 171] So women make sure to optimize your sleep quality before you buy any beauty creams.

picture of skin to demonstrate skin quality
Beauty sleep: the cause for great skin quality?


Let's move on to the last but not least of problems:


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15. Increases risk for psychiatric illness

Bad news...

Sleep deprivation causes an increase in mental problems. In fact, sleep loss and mental issues are interrelated.[172; 173] Symptoms of sleep deprivation and psychiatric disorders, moreover, also overlap.[174]

So while you may experience hallucinations in a psychosis, you may experience the same after being sleep deprived for a few days.

Insomnia and mental issues are also very closely intertwined.[175; 176] Fixing sleep issues should thus be the primary goal for dealing with psychiatric illness. 


Sure: say you've got Post-Traumatic Stress Disorder (PTSD) due to trauma. In that case, sleep is almost certainly disrupted, especially the REM part of the cycle.[177-179] That REM sleep is also important for emotional processing, and disruption of that sleep stage thus inhibits your ability to overcome PTSD.[180-182]

Of course, PTSD is far more complex than I'm letting on here, but sleep disruption is an important component that keeps the vicious cycle intact.

Bottom line? Sleep deprivation makes you sick, stupid, weak, evil, egotistical, infertile, anxious, stressed, and old(er).

And that's not the best you...

I could have included more topics, such as workplace productivity that goes down with sleep deprivation. Fatigued employees cost you $2,000 per year as an employer, for example, due to increased accidents and lowered performance.[664; 665]

But you get the message.

So let's consider the topic of conflicting evidence with regard to sleep deprivation studies:

Studies claiming "sleep deprivation doesn't matter"

Believe it or not, some studies find no negative side effects of skipping a night of sleep.[146; 155]

Such studies are in the minority, however. For every study showing no effect of sleep deprivation, another 10 or 20 to demonstrate that an effect does exists.

The bottom line is that everyone can cherry pick a few studies to show that "sleep deprivation doesn't matter". The totality of the evidence paints the opposite undeniable picture though...

Want more proof for the lunacy of that statement? Let's look at sleep deprivation from another angle:

The ethics of sleep deprivation studies

Interesting fact:

Many studies I've quoted from the 1990s and 2000s still allow participants to be sleep deprived. Examples are only letting them sleep 6 hours per night or even having them pull an all-nighter. 

With new evidence coming out on the destructive health effects of sleep deprivation, medical ethical boards will almost certainly no longer allow such studies because they damage the health of study participants. 

That outcome is very understandable, but also interesting because it entails that the highest quality studies you'll ever have access to have already been performed.

And consider this:

Medical ethical boards will routinely prescribe nicotine to be used if you're a human participant. Sleep deprivation, however, is out of the question because their health deteriorating effects are considered so unethical...

Most people have yet to catch up on that devastating effect of sleep loss though. Shift work is still common in today's society, unfortunately - which tells you all you need to know.

Section 4 summary:

Sleep deprivation has horrible long-term health effects, increasing your risk for almost all modern diseases as well as undermining your well-being, thinking ability, self-control, and even the morality of your behavior. So in the next section, you'll learn how to prevent sleep deprivation at all costs:



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Can't sleep at night?

Unless you've got a serious sleep condition that requires medical attention such as sleep apnea, this section helps you dramatically improve your sleep quality.

Below you'll find 65 tips for better sleep. 

To counter overwhelm, however, let me say the following:

How to apply these 65 sleep quality tips:

These strategies are ranked from most important to least important. And to give you some guidelines on applying these tips:

  • Prioritize integrating the top ten tips into your life, and only then the top 25, etcetera. Using tips located around the 60ish level, such as passionflower and valerian supplements, never compensates for ignoring the top tips such as the tfirst 3: 1) watching the sunrise; 2) getting afternoon sunlight exposure and; 3) getting to bed the same time every day.
  • Hence, the most important sleep advice is placed on top. Less important advice is placed at the bottom. You don't need to apply all 65 tips to get massive benefits.
  • Don't be overwhelmed by the sheer immensity of the information overload. Just focus on implementing one or two tips per week or month at a time. Creating lasting habits is far more important than trying as many of these tips as possible. Steady wins the game...
  • Make sure to test each tip for a sufficiently long amount of time. If you watch a sunrise for just two mornings and then quit to try another tip, you'll never know whether the initial approach was working. You can only test whether a tip is working by implementing it for a longer period of time.
  • If you really cannot implement some of the tips, such as getting some afternoon sun (tip 2), compensate. Tanning beds may replace some of the benefits of afternoon sunlight exposure, for example.
  • If you don't have time to read the complete article, get a basic gist of my claims by scanning the headers and conclusions of each step below. Each of my 65 tips has its own header and conclusion section that contains the main takeaway.
  • You don't need to apply every single tip to sleep better, although implementing the top 20-25 will  work wonders. Tips beyond number 35 or so are not all necessary to integrate into your life - use what you find that works for you in that instance. The first 25 tips are most important and ignoring them will decease sleep quality.

Want the ultimate means to apply these 65 tips? Sign up for the "one tip to rule them all" below:


So without further ado:




1. Watch the sunrise every day

For millions of years, your ancestors woke up in sunlight. History didn't change that fact--at least initially.

So when Socrates was sentenced to death by the Athenian democracy, when the Western Roman Empire fell, when Isaac Newton discovered some basic laws that govern nature, sunlight was their main light source still.

That dynamic only changed with the invention of the electric light bulb in 1879. Thomas Edison allowed you to use light 24-7 - a tendency that still affects your lifestyle today.

From that day onward, people slowly transitioned to sitting inside all day. Artificial lighting became sufficiently strong to allow for indoor lighting (but still has far weaker output than the sun).

That historical process has culminated today, with people only spending a 10% of their time outside.[262; 263] So in 1800, you mostly spent your time outside during the day. In 1900 and especially 2000, you spent most of your time inside.

Another shocker?

Much of what is called "outdoor time" is spent inside a car. Spending time in a car is not really spending time outside because you're still out of the sun and behind glass.

But cars are the least of your worries...

The big problem with being indoors all the time?

Indoor illuminance levels are 100 - 1,000 fold higher outdoors than indoors.[264] Your eyes need that bright bight exposure in the early morning to signal to your brain that it's daytime.[265; 266]

Greater lighting intensity exposure during the is associated with increases in slow wave sleep or deep sleep at night.[267; 268] Several sleep disorders can also be treated with greater light exposure - even if you're older.[268]

For the best results, you don't just need bright light exposure - you specifically need bright light exposure early in the day from sunlight.[268]

Waiting until 11 AM to get outside is thus far from perfect and yields sub-optimal results. Again, your ancestors got exposed to bright morning sunlight every single day of their lives.

You should too.

Additionally, bright light exposure may reduce the amount of adenosine outside your cells - an effect only demonstrated in a rat study.[269] Lowered adenosine entails increasing wakefulness.

Light exposure thus lowers sleep pressure, allowing you to feel more awake - even after a bad night of sleep.

Is it impossible for you get enough sunlight exposure?

Supplement with red light therapy during the day. Nothing replaces sunlight though, but red light therapy can at least avoid some of the problems of a light deficiency.

Morning time exposure is not the only type of light exposure you need though. The next sleep tip considers afternoon sunlight exposure.

Conclusion: Sunlight tells your brain it's daytime. Without that impulse wakefulness and your circadian rhythm are off. A less well functioning circadian rhythm lowers sleep quality at night.



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2. Get afternoon sunlight exposure

a couple at the beach getting exposed to sunlight to increase their deep sleep quality and quantity

Just getting some morning sunlight exposure is not enough though - you need at least some afternoon exposure as well.



Morning sunlight does not contain any "ultraviolet B". That type of ultraviolet light only reaches the earth's surface when the sun's angle to the earth is higher than 40 degrees.

In turn, that ultraviolet B light is necessary to create vitamin D in your skin.[270-272] 

And before you ask, no, I don't think taking vitamin D supplements have the same benefits as getting ultraviolet B exposure through sunlight. I've laid out that argument in my blog post about the safety of tanning beds. In that blog I claim (with good evidence) that ultraviolet light exposure has benefits of its own.

Ultraviolet light has benefits for blood circulation, mood, cognitive performance, and blood pressure, among others.

The problem? 

At least 40% of US adults are vitamin D deficient.[273] In Australia, that 30%.[274] In France, 80%.[275] And these studies don't even use the benchmark of adequate vitamin D levels that's present in modern hunter-gatherer societies.

The issue is probably worse than expected...

Vitamin D is a great measurement because it's a benchmark for the amount of sunlight exposure you're getting, and how adequately your body is using that sunlight exposure for health benefits.

So with low vitamin D levels you're either:

  1. Not getting enough exposure around noon, so that your body never produces vitamin D in the first place
  2. Not able to properly use sunlight exposure because you may have a magnesium deficiency, for example.[276; 277]

So let's look at the effects of getting your vitamin D levels on sleep.

First of all, low vitamin D levels are strongly associated with lowered sleep quality.[278-282; 284] With lower vitamin D levels, you're at higher risk for sleep disorders, shorter sleep duration, and more daytime sleepiness.

Now here's the nice part:

Upping your vitamin D levels reverses that problem. In fact, you'll fall asleep quicker, have higher quality sleep, and sleep longer with optimal vitamin D levels.

Want to know more? Read my guide on sunlight exposure and vitamin D status to optimize the sunlight exposure in your life.

Conclusion: You need sunlight exposure during the afternoon to produce vitamin D. Vitamin D supplements don't yield all the benefits of sunlight exposure. Getting your levels up through sunlight exposure is thus advantageous, in part because it supports better sleep.



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3. Get to bed the same time every day

You know the drill: on Friday night, you stay up until 2 AM because it's weekend. You then sleep in until 11 AM (at least, if you don't have kids). You repeat that pattern on Saturday.

On Sunday, it's hard to sleep at 11 AM because you're only up for 12 hours by then. To you fall asleep at 1 AM, and at 6 AM the alarm goes off once again.

Unfortunately, it's showtime...

You're sleepy and don't function perfectly on Monday. From Monday night to Thursday night, you're sleeping from 11 AM until 6 AM. Well, you don't sleep that great but you'll resolve to make up again in the weekend right?

Not so quick...

That changing sleeping pattern is devastating to your health and performance. 

Varying bedtimes throughout the week creates what is called "social jet lag". 

Let me explain...

During a "normal" jet lag you get when traveling time zones, your body has to readjust to a different day and night rhythm. Social jet lag is similar--the only difference is that you're not traveling. 

The kicker?

Social jet lag also decreases your ability to function at work, puts you at risk for illnesses such as heart disease and gut problems, lower quality of life, and higher overall stress levels.[285-288]

Jet lag decimates your sleep architecture: you'll take more time to fall asleep, sleep less efficiently, and spend less time in REM and deep sleep.[289-292] You'll also be more sleepy and less motivated during the day.

Now you're beginning to see the problem: Many people in today's society are unintentionally jetlagging themselves.

The solution is very simple: go to bed the same time of the day and wake up during the same time every day.

I'm fully aware that today's society is not conductive to that endeavor--but that's a shortcoming of society--not you. Your biological nature has evolved over billions of years and cannot be changed at a whim. Insofar societal rhythms do not accord to your biology, they deteriorate your health. 

And insofar you ignore that biology you'll still suffer the consequences. 

Let me give you an analogy:

Remember the time almost everyone was smoking? I'm 33, so I can still recall that period. Even though everyone smoked the habit still had health consequences. The same is true for creating social jet lag a couple of times per week.

The "but everyone does it is thus not a valid argument..."

The solution is to simply shift your mentality.

If you want to party, do so during the day. Visit a festival at the beach instead of going to the night club. Tell your friends with benefits to visit your on Sunday morning instead of Saturday night. Watch a Netflix episode at 7 AM before work instead of midnight.

But please don't jet lag yourself...

Of course, don't be too stringent about the rule either - staying up late on New Year's Eve isn't the end of the world. If you consistently vary your sleep schedule you'll develop a problem though...

On another note, if you had a night of terrible sleep, make sure not to go to bed very early either. Early bedtimes will throw off your rhythm and make the problem worse. Instead, go to bed at your normal time - your sleep quality will increase that night and compensate for hte earlier sleep loss.

Conclusion: Your circadian rhythm wants stability. If your bedtimes and the time you wake up vary much that circadian rhythm is thrown off and sleep quality suffers.



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4. Wear blue blocking glasses during the evening  

Recall I told you that light affects your circadian rhythm?

Well, at night that bright light exposure is a huge problem. You see, you need melatonin to fall asleep quickly, stay asleep, and get good sleep quality.[293; 294; 297-299] Some evidence to the contrary exists though.[295; 296]

Fortunately, multiple new studies now confirm that blue blocking glasses do increase sleep quality - a fact well known by those who experiment with these glasses.[299-302]

The problem?

In today's society, light bulbs, screens, and billboards all put out unprecedented amounts of blue and green light. Both types of light wake you up and suppress melatonin.[303] Blue blocking glasses prevent that harmful light from entering your eyes after sunset. 

You can learn more about blue blocking glasses in my free guide on the topic.

Get blue blocking glasses at Ra Optics with a 10% discount if you enter discount code NBH1 - Ra Optics glasses are so stylish that they can be worn outside the house. If you want to test whether blue blocking glasses work for you, test a cheap $10 pair inside your house first.

Sure, the cheap blue blocking glasses look weird, but you'll get a great first impression on how dramatically your sleep quality improves. 

You won't be disappointed...

Don't want to wear blue blocking glasses?

Use red light bulbs throughout the house at night. Install Iris software on your computer as well. Install blackout curtains everywhere as well.

But believe me, wearing blue blocking glasses is easier as it's also the only way to block blue and green light exposure outside your home.

Conclusion: Blue blocking glasses prevent bright light from entering your eyes after sunset, helping melatonin levels build up in your brain. Melatonin is necessary for sleep quality.



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5. Quit shift work as soon as you can

"Say what?!"


I feel you...

I've been there before.

I worked as a bouncer during some nights and really enjoyed that job. But you know what? I was ruining your health with that behavior and so I quit. I recommend you do the same thing.

Here's the kicker:

There's no cure for the sleep impairments caused by shift work. None. Nada...

So when that truth hit me, I quit.

If you really do need to engage in shift work, however, at least intend to quit that work in the long term. I'm fully aware that some people need to support a family and cannot quit their job at a whim.

Shift work does causes tons of different health issues, such as:[305-310]

  • Trouble sleeping, daytime sleepiness, and fatigue
  • Decreased sleep quality and quantity 
  • Lowered quality of life and more mental problems
  • Increased risk of cancer, heart disease, and diabetes
  • Lowered cognitive and physical performance
  • Poorer functioning family and social life

In short, almost every area of your life is negatively affected by shift work. 

The catch?

Up to 30% of the population in developed countries are employed in rotating shifts - an insane number.[304; 307]

From the perspective of circadian biology, that 24-hour economy that lies at the basis of promoting that shift work is a sham. In biology, night times are for sleeping and day times are for working - confusing the two slowly destroys your health over time.

Conclusion: With shift work your circadian rhythm can never assume a stable day and night rhythm. That inability has devastating long-term health consequences, and I highly recommend quitting shift work if you're in a financial position to do so.

Let's move to another sleep wrecker:



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6. Manage your coffee intake (wisely)

a picture of black coffee

The famous French Diplomat Charles Maurice de Talleyrand stated around the period of the Napoleonic wars that coffee is:

“Black as the devil, hot as hell, pure as an angel, sweet as love.”

Today's science proves Talleyrand right - at least in one sense. Depending on you respond, coffee can either be "black as the devil" or "pure as an angel". Coffee is also "sweet as love" due to its potential to make you feel great, in the short term (for some)...


Let's find out:

Individual differences in metabolizing caffeine

Depending on your genetics, your liver may metabolize caffeine quicker or slower.[311; 312]

Consequence? In the first instance you're very lucky--in the second instance you're out of luck.

Why care?

Well, coffee is the most frequently used drug in modern society - even more so than alcohol and nicotine (from cigarettes). Coffee also affects sleep.

Now here's the problem:

The more caffeine present in your system around bedtime, the lower the amount of slow wave sleep you'll experience.[313] You'll wake up more and spend more time in NREM stages 1 and 2, instead of 3 (which signifies deep sleep).

So the more caffeine you take in at the wrong times of the day, the poorer your sleep becomes.[313] A dose-response relationship thus exists between caffeine levels before sleep and sleep quality deterioration.

I'm not saying that all caffeine is bad though. What I'm saying is that having caffeine present in your system before sleep is bad.

And there's another issue:

With age, you're generally becoming less tolerant of caffeine.[313; 314] Organ function goes down with age, making your body metabolize the drug slower. Deep sleep is thus more likely  heavily impacted by caffeine if you're older - even though you already have less of it.

Even youngsters are not safe though:

Caffeine "will certainly disrupt sleep if taken 6 hours before bedtime.[315] And the problem gets even worse: the half life of caffeine can range anywhere between 2 and 12 hours.[316; 317]

A half life is the time it takes for a substance to lose 50% of its biological potency in your body. Simply put, if you consume 2 cups of coffee at 10 AM, and caffeine has a half life of 12 hours in your body, you'll still have 1 cup of coffee present in your system at 10 PM, just before you go to sleep.

That's a huge issue.

The worst part?

After some time you won't even feel caffeine lowering your sleep quality anymore.

Want to take caffeine anyway? Add "theanine" to your caffeine.

Theanine, a compound in tea, may have an inhibitory effect of the sleep-disruption quality of caffeine.[318-320] So it's generally wise to combine the two compounds - theanine is treated in tip 56.

But I'm not done with treating the effects of caffeine yet though. Let's explore the compound from another angle:


Remember adenosine? The more adenosine outside your cells starts to bind to adenosine receptors in the brain, the sleepier you become.

Caffeine prevents that binding of adenosine which subsequently wakes you up.[204; 206] Caffeine binds to the adenosine receptors, making you feel more awake. Over time, however, the body compensates for that effect by increasing the number of adenosine receptors in your brain.

At that point, adenosine has built up massively in your brain, and caffeine can no longer bind to all receptors anymore. The end result is that you'll feel much more tired even though you're drinking lots of coffee.

You're now addicted...

How you respond to caffeine depends on you as a person though:

Biologic individuality

There's no one size fits all recommendation possible regarding coffee consumption and sleep quality. 

Some people, like highly respected nutrition guru Chris Masterjohn do very well on more coffee. Other people like me need to wind off completely or cycle the stuff.

Test for yourself or do genetic testing if you cannot gauge the results. One law is clear though: you don't know how you respond to caffeine if you've never tested a life without.

Conclusion: How your sleep is affected by coffee depends on your individual circumstances - such as age and genetics. Winding off coffee and going caffeine free for 6 weeks is the best way to find out how your sleep is affected.



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7. Supplement with magnesium and zinc

Cheapest fix to solve your sleep issues?

Make sure you're consuming sufficient magnesium and zinc. Many people are running into trouble in that regard:

I've estimated that up to 80% of people are magnesium deficient, with about half having a severe magnesium deficiency. Zinc deficiency is located around 10-20% of the population in the developed world.

You need both minerals for high sleep quality -  so let's explore them:

Magnesium and sleep quality.

Finally, the fun part:

Magnesium reverses some of the declines in sleep efficiency that occur due to aging.[321] The amount of melatonin produced and deep sleep quality may also increase.[324]

Magnesium may both reduce the time it takes to fall asleep as well daytime sleepiness.[323]

In mice, both magnesium deficiency and excess reduce sleep quality while optimal levels produce the best results.[322; 325] 

While more research is needed, anecdotally many people have huge benefits by fixing their magnesium deficiency.I did too...

Zinc and sleep quality.

The effects of zinc on sleep quality are even more sparse than magnesium.

What is known is that higher zinc levels are associated with normal sleep duration, instead of the unhealthy very short or very long levels.[326] 

In children, higher zinc concentrations in the bloodstream are associated with sleeping longer, waking up less, and higher sleep quality.[327] Across different ages, zinc levels also predict higher sleep quality.[327]

The best part?

Supplements are dirt cheap:

How to supplement magnesium and zinc.

Get some high quality magnesium supplements in pill form, or magnesium oil (don't use more than once per day) and zinc

Zinc is pretty easy to get from food though, if you eat some oysters once in a while. Due to soil depletion, it's hard if not impossible to get sufficient magnesium from food alone.

Conclusion: Almost everyone is magnesium deficient even though the mineral is necessary for optimal sleep quality. You probably need to supplement. Zinc deficiencies are more rare, especially if you frequently eat shellfish and red meat. If not, change your diet for the better.

oysters, displayed as an example of zinc-rich food
The best zinc-rich food in the world...


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8. Make your bedroom completely dark

The light originating from billboards and street lanterns can enter your bedroom, and wake you up at night. That light is called "light pollution".

By now you should know light is not "innocent". In fact, light pollution ruins your sleep. That pollution is everywhere. Many types of technology are emitting artificial light at night right now. Light bulbs and screens are most problematic.

And the worst part?

Even 5 or 10 lux of light lowers total sleep time and deep sleep quantity.[328] As a point of reference, the bright midday sun can exceed 100,000 lux in illuminance. Just a slight stimulus thus has a radically big effect.

A blue light emitting thermostat display may thus lower your sleep quality.

You'll not only get less of the NREM 3 (deep) stage of sleep, but also lower quality of that specific sleep period.[332] REM sleep quality also decreased.

(In another study, the REM portion of the night may slightly increase with light exposure, however.[328])

So light at night is a problem. Artificial lights outside your house keep you up at night (so that you'll end up in bed later), keep you awake, decrease your total sleep duration, and make you more sleepy during the day.[333]

Subjectively, if you're exposed to light at night you'll also judge your sleep quality to be lower.[333]

The solution is very simple though:

Get some blackout curtains for your bedroom to avoid light from leaking in. Alternatively, get a high quality sleep mask. I use both...

Don't use alarm clocks that emit any light or other electronics.

The bright side?

Sleep mask technology has massively improved in the last 5 years. Blocking all light leakage from the sides of a sleep mask is now possible.

One caveat:

The effects of artificial light exposure at night are poorly understood right now. light has far reaching effects upon your behavior. Light pollution may increase your risk of taking hypnotic drugs at night, for example.[330] Those drugs are probably taken to compensate for lower sleep quality and to wind down.

And there's more...

Human beings are not the only ones affected by artificial light at night--wildlife also suffers. Bird sleep 40 minutes less per night when they're exposed to even low levels of artificial light.[329; 331]

That reason alone should tell you human beings are not safe of the consequences of light pollution either.

Conclusion: Cut all light from your sleep environment as much as possible, as even exposure to small quantities lower sleep quality.



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9. De-stress using meditation, socializing, or other relaxing activities.

As always, let's start with the basics...

How chronic stress affects health and sleep.

Chronic stress is devastating to your health.

Higher levels of chronic stress are associated with lower sleep quality and more frequent sleep disorders (such as insomnia).[334]

Chronically high stress hormone levels such as cortisol, adrenaline, and noradrenaline may play a role in that chronic stress.[334] In essence, your body responds to psychological stressors (such as a deadline or dissatisfaction with your job) as if you were under physical threat.

That interpretation of your body of being under a physical threat keeps you awake, ready to fight or flee. And that attitude and its interrelated physiological consequences are not beneficial for sleep quality, however.

The more chronic stress you have, the more likely sleep disturbances become.[335] Psychological stress may even accumulate over your lifetime.[335] The consequence is less deep sleep and REM sleep, all while having a lower sleep efficiency.[336]

Interesting fact:

The more stress you have, the more magnesium you need as well.[337] So re-read tip seven if you're chronically stressed and up your magnesium intake.

Prevention is the best "solution" against becoming chronically stressed. Prevention entails that you'll have to engage in relaxing activities before you actually become chronically stressed or worse: burn out.

Countering chronic stress to increase sleep quality.

Many people need to actively plan on relaxing once in a while - preferably every day before bedtime. 

Socializing with friends or spending some time in the wood or beach are excellent options for lowering stress levels also.[338-344]

Mindfulness meditation is another great choice to wind down and stop being stuck in your mind. Mindfulness directly increases sleep quality, for example.[345] The increase in sleep quality may be even superior to some sleep education courses (that teach you to go to bed the same time every day, for instance).[346]

If you've got a condition, such as insomnia, cancer, or fibromyalgia, mindfulness will also increase sleep quality.[347-350] Such conditions are often characterized by worrying about the future or past--mindfulness moves you into the here and now.[351]

Read my 100% free guide on mindfulness meditation to learn more about the topic.

As a side note, good evidence exists that mantra-styles of meditation produce even quicker and deeper results - mantra meditation is part of my paid Health Foundations Program course.

two kittens that are sleeping together, symbolizing their presence and minfulness and happiness in the moment
Masters of mindfulness and de-stressing


Conclusion: Chronic stress lowers sleep quality - it's highly recommended to use activities such as mindfulness, socializing, or fun activities to overcome the issue. Mindfulness can prevent you from excessive worrying.



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10. Kill acute stress as soon as possible

Have you perfected your light exposure during the day, and are you avoiding all blue and green light at night? Have you put canopies over street lights, installed double black out curtains, and are you wearing a sleep mask on top of that?

Well, you're not there yet...

Ever got an angry e-mail at 22:00 just before you were going to sleep? In that case, cortisol and adrenaline shooting through your body. And even though it was unfortunate, you became very wide awake again, unable to sleep.

Of course, you could just wait two hours before you're calmed down. A better solution, however, is to use techniques to immediately get relaxed again.

Box breathing is an example of a relaxation technique which achieves that purpose.

With box breathing, you're breathing in and out for an "x" amount of time. You also hold your breath after breathing in and out for that "x" period.[355-357]


If you're using 4-second box breathing, you're breathing in for 4 seconds, pausing for 4 seconds, breathing out for 4 seconds, and pausing again for 4 seconds. Doing so calms your nervous system and allows you to return to rest.

Hint: make sure to breathe through your lower belly--not your chest.

Using mindfulness which I've talked about before is yet another option:


Bottom line: even if you do everything perfectly in terms of light, a fight with your spouse will still have very negative consequences on sleep quality. Your psychological responses to events that happen in your life do matter

The worst part about acute stress?

Most psychological stress is useless. 


Almost always the stressor - the cause of the stress - is imaginary. With an angry e-mail, you don't have a problem right now. The fight or flight response you're getting revolves around your future or past, not your present moment.

Getting stressed doesn't actually solved the problem.

The problem gets worse though: over time you'll get hardwired to get stressed.[352-354] A brain area called the "amygdala" will sound the alarm bells quicker and quicker in your brain - leading to the characteristic fight and flight response.

Rumination is an example of such a continuous fight and flight response. Ruminating over problems is associated with sleep quality dropping down.[431-434] Ruminating on worries is especially harmful.

The more you "train" your stress pathways by ruminating, the easier that thought pattern is recruited in your brain. For that reason it's wise to kill acute stress as much as possible.

If you'd like to learn more then read my guide on (chronic) stress.

Conclusion: Use slow box breathing or mindfulness to counter an acute stress response. Acute stress before sleep decreases deep sleep quantity and quality.



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11. Reduce non-native EMF exposure

The topic of "non-native electromagnetic frequencies", or nnEMFs is extremely complex.

Not only are tens of thousands of studies published on this very issue, there's also a big scientific debate around the safety of nnEMFs. Big tech companies generally claim that nnEMF is competely safe but also have a big incentive to do so.

Institutions such as the World Health Organization consider nnEMF potentially harmful - even potentially carcinogenic.

You may think: "nnEMFs? That words sounds like "LMFAO" (laughing my freaking ass off) or "YOLO" (You only Live Once).

I hate to break it to you, but nnEMF is not that much fun...

The simplest way to explain what nnEMF is, is to begin with natural EMFs. Nature is filled with light, radiowaves, and microwaves - which are all EMFs or "electromagnetic frequencies".

Modern technology, such as cell towers, screens, smartphones, and basically any device connected to the Internet of Things emits electromagnetic frequencies of their own. 

Because nature didn't create these electromagnetic frequencies, those stemming from technology are called "non-native" EMFs.

Some of these non-native EMFs are less harmful while others are more harmful. X-rays close to your body are certainly harmful, for example - a fact well established for some time.

What many people don't know is that cell phones worn close to their bodies are almost certainly harmful as well. 

In animal studies, exposing yourself to radiowaves such as used in cell phones clearly causes heart and brain tumors.[357] The problem gets bigger though: that high-quality study was carried out with 2g and 3g technology. The world is now mostly using 4g technology, which has higher power density, and worse, is moving to 5g as well.

Non-native-EMFs farther away from your body are thus probably unsafe as well. 

In some studies, nnEMF causes sleep disorders, insomnia, a decrease in both deep and REM sleep, changes in EEG readings, and more.[359-363]

Solution? Check the following list:

  • Remove electronics as much as possible from your bedroom. Smartphones need to be put in airplane mode and DECT phones are to be removed in their entirety.
  • Let an electrician install a circuit breaker in the bedroom - you'll remove dirty electricity that way during your sleep. Use dirty electricity filters if using a circuit breaker is impossible.
  • Turn off WiFi at night, or better: don't use WiFi at all.
  • Remove your smart meter or ensure that thing doesn't work anymore. Putting aluminum window screen over that smart meter blocks all emissions. Putting chicken wire around that meter may also work.
  • Never use a phone close to your body. Even Apple's own manual states that you should always keep an iPhone at a 15 millimeter distance from your body. 
  • Wire devices with an Ethernet connection whenever possible. Don't use your laptop at your lap - that's why these devices are no longer called "laptops" but "notebooks". Tech companies don't want to be sued for the damage they cause...

Those are the most important basics.





Conclusion: Technology that emits electromagnetic frequencies such as WiFi or smart meters almost certainly affect sleep quality according to the latest research. Keep your bedroom (and if possible living environment) free from such devices.

Moving on to another electromagnetism-related topic:


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12. Get a magnetico sleep pad

A magnetico sleep pad can offset some of the damage induced by Alternating-Current (AC) electric fields. Technological devices in your environment can produce that AC exposure.

Why care?

Your body is electromagnetic as well and functions on the DC current.[364] EMFs from technology affect that current.

Your body also exhibits pulsed electromagnetic frequencies current during sleep - measurable by EEG during sleep.[365] 

Before humans controlled electricity, the relationship of biological beings to nature used to be very different. During billions of years, many animals also slept on the ground. By staying close to the ground, you're affected by the magnetic field of the Earth.

A magnetico sleep pad supplements that magnetic field of this planet even though you're not sleeping on the ground anymore.

Why get one?

The intensity of that magnetic field on the Earth is declining - you've no longer got the exposure your ancestors had thousands and millions years ago. A magnetico slep pad supplements that field from the Earth at night.

I don't have a discount code or affiliate deal with magnetico but I do recommend their product. So while I'm not getting paid for recommending this product, the magnetico is the only magnetic pad in its kind that I'd recommend.

Many magnetic field products emit positive magnetic fields, which can have side-effects in comparison to being exposed to purely negative magnetic fields. Used correctly, the magnetico only exposes your body to negative fields (which are healthy during sleep).

Conclusion: The magnetico sleep pad simulates sleeping on the ground and can partially protect you against non-native EMF in the environment.



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13. Ground during the day

For years many experts were talking about the benefits of earthing. The problem, however, was that no high-quality studies were available on the effect.

That predicament has changed in 2019. 

One study investigated the effects of grounded sleeping on post-exercise recovery.[366] While sleep quality was not measured, grounding did improve recuperation. Indirectly, an effect on sleep quality may thus be hypothesized.

From a physics perspective, moreover, it's very likely that grounding will increase sleep quality. Many modern humans are never grounded anymore, even though grounding is one of the ways in which you can lose excess protons to the environment.

To ground you need to have your naked skin touch the Earth's surface, or an object that connects to that Earth. Standing with your bare feet in the grass is the easiest way to ground, preferably in the morning. 

Be very careful with grounding mats inside buildings - you can become an antenna for dirty electricity and increase your nnEMF exposure that way. Grounding pads can thus decrease your health and sleep quality, unless you know what you're doing.

And while more is better, just 5 minutes of grounding a day will get the needle moving in the right direction...

a field of grass that can be used for grounding
Don't just worship the sun - worship the grass as well.


Conclusion: Grounding is probably very important for sleep quality even though no direct (unbiased) studies exist to confirm the effect.


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14. Tape your mouth


Many people breathe through their mouth during their sleep, even if they don't have sleep apnea. 

You might too and not know it yet...

To solution is to tape your mouth during the nighttime so that you'll automatically breathe through your nose.

Nasal breathing has become more rare in today's society even though it's the healthiest way to breathe. 


Cover about 4-6 inches of your mouth with tape. Consult your physician first before doing so though so that breathing problems can be ruled out.

The upside? Nasal breathing does decrease snoring and sleep apnea - both are horrifying for sleep quality.[382-385]

And while no hard evidence exist, circumstantial evidence hints that nasal breathing is far superior for maintaining sleep quality.[386-388] My own experience as well as that of the people who I've coached comes to the same conclusion.

In general, the more you practice nasal breathing, the better you become at it. Consider my Health Foundations Program if you'd like to learn more about breathing optimally.

Will you look crazy to your spouse with a taped mouth?


In fact, I've had spouses of the people I recommended mouth taping to complain to me about the beavior.

Will you sleep better with a taped mouth?

Almost certainly...

And if you cannot breathe through your nose currently, skip to sleep tip 50. 

Conclusion: Taping your mouth during nighttime to force nasal breathing almost certainly improves sleep quality. Only use this tip if you've got not breathing issues such as sleep apnea.



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15. Use a healthy mattress

Many people spend tens if not hundreds of thousands of dollars on a newer and bigger car, but are unwilling to spend much money on a better mattress.

Crazy but true. 

And that's weird because you're spending 6-9 hours on a mattress each day - a whopping third of your lifetime.

So arguably, your mattress is the most important piece of furniture in your home.

And you know what?

Mattress quality does impact sleep quality.[389; 390] 

Buying the right mattress is more complicated though:

Subjective assessments of mattresses are not always the best indicator of sleep quality, because EEG analyses disagree with subjective judgments.[390]

In general, however, you'll want a mattress that's neither too soft nor hard.[389; 391] 

What's surprising to me when looking at the science is that medium-firmness consistently scores better than harder surfaces.[392] I did not expect that outcome. One caveat is that mattress evaluation is very subjective, and that judgments about what "hard" or "medium" entails can differ also.[393] 

To make matters worse, for some people, somewhat softer mattresses are best, and for others, harder ones. No matter which mattress you take, all organic is best.


You'll want a mattress that doesn't contain any toxins that are allergenic and you don't want to expose your body to substances that carry health risks such as flame retardants.

The problem with cheap mattresses is that your face is planted into that object all night. Next to inhalation, skin contact can also be a mechanism for toxin exposure. 

Toxic mattresses are thus main sources of toxin exposure...

I've not made a choice on the best organic mattress out there yet. I do have some pointers and recommend you be careful with:

  • Trusting organic. Even though a mattress is advertised as "organic" not all compounds in the mattress may be so. Always inquire whether the mattress is 100% organic, and if not, which elements are not and why. Ask lots of questions when buying.
  • Make sure the mattress doesn't contain flame retardants, Volatile Organic Compounds (gases that are damaging to your health), and artificial materials such as polyurethane, memory foam, or synthetic latex. All such materials can affect your health, and may do so more or less depending on your susceptibility.
  • Coil springs. The metal in those springs attract non-native EMF. Non-native EMF was considered in tip eleven. 

Choose a mattress made from natural materials such as wool, cotton, hemp, bamboo, coconut, and natural latex. Shop for organic mattresses HERE. Again, always inquire how those compounds are processed - e.g. whether flame retardants have been added.

Conclusion: You spend a third of your life on a mattress and you're breathing in any substances emitted by it or located on it. Invest in high-quality organic materials.


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16. Optimize the bedroom temperature

Remember sleeping on a freezing winter night with your windows opened? Or recall your house never cooling down during a day of tropical temperatures?

In those cases your sleep probably suffered. 

Guess what:

Cool (but not cold) temperatures are best for sleep quality. Keep in mind that most people's bodies are cooling down during the night - a sign of a slower metabolism during sleep.

a cat that is sleeping on bed
The leather sofa was too cold human, so I'm taking this sleep place to increase my slow wave sleep.

Warming a cold room should be relatively straightforward - any kid can accomplish that feat by turning up the thermostat. 

But you've got other options:

Wearing bedtime socks is another tested method for increasing sleep quality: you'll fall asleep quicker, sleep longer, and have higher quality sleep.[394]

Nonetheless, I would also investigate my health if I couldn't warm my feet naturally inside a bed. My hypothesis is thus that wearing warm socks compensates for the body's natural inability to warm itself - a possible sign of a slow thyroid (i.e. "hypothyroidism")

(More on hypthyroidism in tip 57.)

Temperature has a shocking effect on sleep quality: Warming your body can almost double the amount of deep sleep you get at night if you're an elderly person.[395]

In young healthy people, warming the room has almost no effect.[396] The effect of heat is thus age-dependent.

What temperatures are best depend on circumstance though. If you've got a sleep condition such as sleep apnea, 24 degrees Celsius makes you sleep better than lower temperatures.[397] For a young guy like me, 24 degrees Celsius (75F) is way too hot.

Animal studies also show that higher temperatures generally produce higher sleep quality.[398; 399] Warm is better than hot and especially cold. 

Of course, if it's 30 degrees Celsius (~85) you'd want to lower the thermostat reading. Lowering the temperature can be done in several ways:

One way is to use air conditioning. Another method is to use a bedjet to control temperature inside the bed. That bedjet blows cool temperature under your blankets, cooling your body down in the process.

The advantage of that bedjet is that it doesn't emit any non-native EMF near your body so that your health is not at risk due to technology.

Conclusion: Both hot and cold temperatures lower sleep quality. Cool (but still warm) bedroom temperatures are best. Cool or heat your bedroom to achieve that effect.


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17. Exercise - but not too late.

Exercise can improve sleep quality - even if you engage in it at times you shouldn't from a circadian perspective.

Normally, human beings hunted and gathered during the daytime. That pattern is still present in modern hunter-gatherers today.

So at first sight, you'd expect morning and afternoon exercise to be superior.Nonetheless, evening exercise does improve sleep quality.[367-369]

The question, of course, still remains whether morning, afternoon, or evening exercise has most benefits. That question has not been definitively answered, unfortunately.

Overall, exercise does improve both sleep efficiency and the amount of slow wave sleep you get each night.[370; 371; 374; 376]

In fact, sleep and exercise are mutually supportive.[372] The better your sleep becomes, the better your exercise performance--and the fitter your are, the better your sleep becomes again.

Different types of exercise can be used, such as resistance exercise or cardio.[375; 377]

Some studies even suggest that exercise can be used to buffer against the negative effects of excess stress.[373] The outcome was found in younger people though - if you're older stress on top of stress will more likely be detrimental to sleep quality.

So don't abuse exercise...

With insomnia, the relationship becomes more complex: exercise might only cause a slight increase in the amount of deep sleep, while the insomnia itself is not cured by exercising.[378-381] The reason for that outcome is simple: exercising does not fix the underlying issue of circadian mismatches that causes insomnia issues in many people.

Conclusion: Moderate amounts of exercise increase sleep quality. To err on the safe side, morning, afternoon, and early evening exercise are probably best. Late night exercise probably disrupts your rhythm - especially if intense.


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18. Avoid late night eating

Eating just before bedtime? You'll almost certainly lower your sleep quality.

Keep in mind that in some circumstances eating before bedtime might be highly beneficial. An example is taking honey before bedtime. While that practice is not optimal, sometimes raw honey can be highly beneficial for suppressing a stress response in the middle of the night.

Notice the word "sometimes".

If you're waking up at 4 AM because you've got low blood sugar, taking honey before bedtime is probably more helpful than hurtful. In other cases, the opposite is true.

Overall, when you eat matters. Eating is a circadian signal just like light is - which I've treated in the first few tips described here.[400]

That circadian rhythm not only affects your brain but has consequences in all cells of your body.[400] Your liver may think it's daytime if you eat at 10 at night, for example, just as your brain does.


Avoid eating for 12-16 hours a day.[401] Even if you consume the same number of calories, consuming that food in a smaller time window such as 6 or 8 hours has massive health benefits.

And there's more:

Eating before bedtime is also independently associated with disrupting the circadian clock and less time spent in deep sleep.[402-403] The problem, however, is that a causal link is not yet established in these studies.

Moreover, the most probable reason for that finding is that digestion is overactive during sleep. 

I do consider it very likely that not eating late at night will improve sleep quality. Most people's experience agrees with that assessment. 

Conclusion: Late night eating often makes you eat for more hours during the day, which has negative health consequences. Late night eating also increases digestive requirements, which probably impairs sleep quality.

Moving on to an area where tons of evidence exists:


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19. Manage air quality

Air quality is a tremendously complex subject. I've written about the importance of air quality in the past, as well as one specif pollutant called particulate matter.

If CO2 levels become too high during sleep, sleep quality already goes down, for example.[405]

Particulate matter is more devastating. Particulate matter are tiny little particles that you breathe in, and which can up in your lungs, bloodstream, and even brain. That particulate matter can even contain toxic heavy metals, such as mercury and arsenic.

With greater particulate matter exposure, sleep quality goes down.[406; 407]

It's also very probable that breathing capacity declines, which then indirectly affects sleep quality.[408] Sleep apnea becomes worse with more particulate matter in the air, for instance.[409] NO2, a pollutant stemming from traffic and industry has similar effects.[410]

Even daytime sleepiness and sleep disorders may be caused in children by polluted air.[411] 

Instead of laying out the entire strategy to remove air pollution from your environment, just read my guide on air pollution - specifically the section containing different solutions.

Examples of solutions against breathing in polluted air include:

  1. avoiding polluted areas at peak pollution times;
  2. using an air purifiers;
  3. buying furniture that doesn't emit (too many) toxins;
  4. never spending too much time in a moldy building if you're susceptible to mold's possible devastating health effects and;
  5. using vegetation both indoors and outdoors to block some of the pollutants from entering the building.

In terms of air purifiers, get the Coway AP-1512HH air purifier for rooms up to 530 square feet (~50 m2) and the Alen BreatheSmart 75i for bigger rooms (or apartments) up to 1,300 square feet (120 m2).

My guide on air pollution gives you 10 additional strategies and also explains them in excruciating detail.

picture of polluted air wihch has been demonstrated to lower sleep quality
You don't expect this air to negatively affect your sleep quality? In that case you're out of your mind...


Conclusion: Air pollution lowers sleep quality. Use my strategies to counter air pollution's health effects to protect yourself.


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20. Deal with noise pollution

Remember that time someone woke you up in the middle of the night and you were really irritated?

Overflying airplanes and bypassing traffic have the same effect. And that party in your neighborhood? No bueno for your sleep quality.


Noise exposure causes chronic low-level stress.[412; 413]

And everyone's sleep is hit by noise...

Even in healthy sleepers, removing noise from the environment increases sleep quality.[414] In fact, healthy sleepers may gain a whopping 15-30 minutes of deep sleep per night through that means.


Noise at night wakes you up.[415; 417] The result is less slow wave sleep. With frequently wake-ups you'll feel tired and sleepy throughout the day. The end result is an increase in sleep disorders such as insomnia and hypersomnia.[416]

And the solution is less radical than you'd think. You don't have to move to the jungle to benefit...

Just wear earplugs when you're going to sleep if there's lots of noise in your environment.

Alternatively, get a white noise machine:

So let's consider why both strategies work:

Earplugs can reduce the sensation of noise by up to 1000-fold (equaling 31 decibels - a logarithmic scale). A white noise machine supplies your ears with stable background sound that (partially) overrules the noise pollution in your environment.


And what if you're routinely exposed to tons of noise? In that case, get custom made earplugs.

Also make sure to read my guide on noise pollution for learning 8 additional noise-defeating strategies. Noise is a problem you cannot ignore - sound levels in cities can be 1,000 - 10,000-fold higher than in nature which you have to deal with if you want optimal sleep.

Conclusion: Noise causes chronic low-level stress which inhibits sleep quality. Use earplugs or a white noise machine to lessen the impact. Read my aforementioned guide on noise pollution if you'd like to learn more.


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21. Take your chronotype into account 

"What's a chronotype?", you may ask.

A chronotype is your own individualized circadian rhythm. Several individual variations in how individuals prefer to sleep exist. 

Some people may be a morning person, loving to rise at 6 AM. Others - even if they wear blue blockers - prefer a 1 AM bedtime while rising at 8 AM. 

A gene in relation to your circadian rhythm called "PER3" is partially responsible for your chronotype.[418; 419]

If you'd like to learn more about this topic, reads The Power of When: Discover Your Chronotype.

The best way to find out about your chronotype is to experiment with different sleep patterns. You probably also already know when you're performing best.

Morning types, consist of 10% of the population, perform best between 8 AM and 1 PM. Evening types, consisting of 10% of the population, become more active in the afternoon. The majority of the population (50%) can be found somewhere in between.[420]  

10% of people are unlucky in terms of their sleeps - they are lighter sleepers. 

With a different chronotype, your circadian rhythm responds slightly different to light, for example.[421; 422] Your chronotype will also change throughout the course of your life: teenagers are evening persons, while elderly people shift towards the morning time.

I'm a morning person, and hate parties at 23:00 because I want to be sleeping by then...

How to know your chronotype?

If you're most alert around 10:00 then you're probably a morning person. If you're only getting started after the afternoon and in the evening you're a night owl. If you start kicking ass around 11:00 and noon you're the average majority - light sleepers are also most alert then.

Society has adapted towards the 50% of people who get are in their peak around 11 AM. Other chronotypes like me need to adapt - or better: cope.

Conclusion: Know your chronotype to create your ultimate circadian rhythm. Morning persons should not stay up late. Night owls should not be present in 8 AM meetings.


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22. Inclined bed therapy

Animals in nature often sleep on a hill--not a flat surface. Since the last few years, humans have caught onto that tradition. 

(The tradition already existed in history though, such as with the Egyptians.)


Inclined bed therapy means raising the head-end of your bed by 3-6 inches. As a result, your body will be under increased influence of gravity because your body is now positioned more vertically.

One side of your bed should only be inclined by a 5-degree angle compared to the other side. Inclined bed therapy used to be practiced widespread in history, but no longer is - and that's about to change.


If you've got sleep apnea, your ability to breathe increases with inclined bed therpay.[423] The result is an increase in brain oxygenation at night and higher sleep quality.

With digestive problems, such as acid reflux, inclined bed therapy may also help you.[424] 

No matter what your background, circulation may also improve during sleep on an incline bed.[425] Unfortunately though, lots of evidence for inclined bed therapy does not yet exist.

Going by the anecdotal evidence, however, many people are very positive. People who measure their own sleep quality almost universally prefer an inclined bed to a flat one.

My own experience agrees with that assessment. 

And the best part?

You can simply grab some inexpensive furniture risers and sleep better tonight. A stack of books works just as well as furniture risers.


Putting some object under your pillow doesn't get the job done. For optimal results you don't just raise your head part of your bed while keeping the rest flat - you raise the front of the bed and ensure the bed itself stays flat

And you know what's even better?

Inclined bed therapy doesn't cost you any time.

Set up and win. Free improved sleep. Forever...

Conclusion: Anecdotal evidence is very positive towards inclined bed therapy. Medical studies are promising but few in number. To use incline bed therapy, raise the head of your bed by up to 6 inches while keeping the surface on which you sleep flat.


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23. Have a life's purpose

Don't have a reason to get out of bed in the morning?

In that case your sleep might take a hit. An association exists between having a higher purpose in life and lower frequencies of sleep disturbance.[426; 427]

If you're generally not feeling good, as is the case with depression, your sleep quality is also lowered.[428; 429] So overall, just not feeling good and experiencing no meaning in life reduces sleep quality.  

Even though not a lot of research on this topic exists, I think experiencing meaning in your day is incredibly important.

My point?

I've seen different statistics, and between 65% and 85% of people feel dissatisfied with or even hate their jobs. 

And that's insane...

So if you hate your job you'll probably don't look forward to getting up in the morning. But how do you know whether that's the case for you?

Take this simple test:

Are you already looking forward to the next Friday night? If so, you're probably using weekends as an opt-out of your job and you don't really value what you do everyday.

In that case, make a plan to change your life over time. 

birds flying around and naturally having a purpose in life, contrary to humans
These animals do have a reason to get out of bed in the morning. Make sure you do too.


Conclusion: Have a reason to get out of bed in the morning. If you don't, work on changing your life so that you do.


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24. Keep a happiness journal

A happiness journal is one of the easiest way to improve sleep quality. Grab a sheet of paper. Each morning, write down:

  • 3 things that make you happy
  • 3 positive affirmations
  • 3 planned actions that will make your day great

Each evening, write:

  • 3 things that make you happy
  • 3 things that went well that day
  • 3 things that you could do better next time.

Shockingly simple...

That's all.

The entire process takes you 5 minutes a day max

The process I describe is often carried out with gratitude instead of happiness. In some instances, gratitude can cause indebtedness feelings.[435; 436] Happiness is thus an even better term -- although I don't care which one you use. 

So here's the catch:

Gratitude has been shown to improve sleep quality.[437] You'll fall asleep quicker, stay asleep, experience greater sleep quality, and be more alert during the day.[438] 

Happiness is also associated with higher sleep quality.[439] So either choose gratitude or happiness for this exercise. And believe it or not, but you can work on your happiness in many different ways.

Conclusion: Journaling on what makes you happy increases sleep quality simply because it increases happiness. Happiness, in turn, supports sleep.


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25. Socialize or cuddle

Socializing and loneliness

Let me paraphrase Aristotle:

"He who needs no other humans - who is fully self sufficient - is either a god or beast."

And there's truth to that statement...


Loneliness is devastating to your sleep quality - even in young people who are generally the best sleepers.[526] If you're lonely, you'er more prone to wake up during the nighttime and thus have fragmented sleep, for instance.[528]

Your loneliness even has an effect on the sleep quality of your partner.[527] And even if you do sleep long, loneliness still causes you to be less wakeful during the day.[529]

The bottom line?

If your social relationships decline, sleep quality thus also suffers.[530] 

Social isolation, in most of these studies, has an independent effect of loneliness, and is often more destructive for sleep quality.


Get out of the door more - even though you don't feel like it. Social isolation can make you feel depressed, leading to a vicious cycle of feeling bad, staying home, and feeling even worse.

I know the feeling, as a blogger who spends 60-80 hours writing per week. I need to force myself to leave the house - I'm slowly learning of doing so successfully.

Want to up the ante in your social life and maximize the sleep benefits?


Oxytocin release during cuddling

If possible, give lots of cuddles and hugs to your friends.


Doing so releases "oxytocin", a brain signaling compound associated with physical contact.[532; 533] If you've got sleep apnea and oxytocin is administered to you, relaxation, the total time you sleep, and subjectively-rated sleep quality all go up.[534]

Oxytocin also has an anti stress effect which may indirectly lead to higher sleep quality.[535]

Hugging has a similar response in that it decreases the "cortisol" stress hormone.[536] Simply put, you'll be more relaxed when you hug someone once in a while.

More frequent hugging is associated with higher oxytocin levels.[537] Oxytocin is related to many close social behaviors, such as cuddling, being close to someone, breastfeeding, and orgasm - and thus not just a cuddling hormone.

Hugging and cuddling are the easiest way to get your daily hit though - breastfeeding is kind of hard for me as a male...

Conclusion: Humans are social animals. Even with a perfect circadian rhythm and diet, your sleep will still suffer if you're socially isolated. Cuddle and hug (people you like and who like you) for bonus points.



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26. Get out of bed if you cannot sleep

If you stay in your bed while lying awake your brain creates an association with insomnia with that bed.

So if you're spending 30 minutes or or longer in bed before you fall asleep, insomniac behavior gets reinforced.

Fortunately, the issue is often fixable.[445] The solution is to get out of bed if you're unable to sleep for longer than 20 minutes.[444] 

Most insomniacs don't deal with an inability to sleep that way though: they try harder to sleep...

Trying harder" to sleep also has destructive effects though. At best, you'll waste your energy with trying. At worst, you'll end up in a fight or flight response and ruminate, further reducing your inability for sleep.

Instead, get out, do something else, and wait for you to get sleepy again. Of course, wear your blue blocking glasses as prescribed in the fourth tip.

If you don't want to move out of bed, shift your focus to relaxed resting instead of trying to sleep. The "resting attitude" is far healthier to the associations your mind creates around sleep than thinking you "need to sleep now or I'll be unrested tomorrow".

And if you wake up in the middle of the night, also try not to spend hours lying awake in bed either. 

Conclusion: As Yoda says "do or don't - there is no try". If you cannot sleep get out of bed and go back to bed an hour later. Trying harder to sleep entails failing harder - either you sleep or you don't.



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27. Drink alcohol - during the daytime.

Surprise, surprise:

No nighttime drinking allowed.



Society has it completely backward once again in this case. Alcohol before bedtime massively reduces sleep quality.[447] 

You'll be disturbed more easily and experience less deep sleep.[447] And the more frequently you drink, the less deep sleep you'll experience.[448] Alcoholics often have almost absent slow wave sleep, for example.

In some studies, alcohol also increases deep sleep quantity though.[449] That outcome may be explainable through an increased need for recovery instead of genuinely getting better sleep.

Alcohol also reduces anxiety, which may explain some of its positive effects on sleep quality in some studies. In the long-run, it's better to meditate than use alcohol to deal with anxiety though.


The more frequently you use alcohol before bedtime, the worse the effects will be.[450] Throw out that night cap, and have one or two drinks after work - in the early evening sun.

drinking alcohol together at a field during picknick
"An afternoon instead of nighttime drink a day keeps the sleep doctor away?"


Conclusion: If you drink, do so during the daytime. Drinking before bed reduces sleep quality. Two glasses of wine with dinner are processed once you go to sleep and thus still safe.


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28. Don't have sex very late at night

There I go again...

Late night is actually the worst time for procreation. Late at night you should be sleepy - even if you're an evening person.

I already know what you think: "no alcohol, no eating, and no sex at night!?"


Again: Nights are for sleeping. Daytime is for excitement and activity. If you really want to have sex, the morning time is actually best. 

Hormones such as testosterone peak early in the day.[451]

Remember that the circadian rhythm affects all processes in your body, and thus also fertility. Trying to get pregnant during the night may not be your best option.

Unless your partner is a night owl, bring back that morning sex. Early evenings might be best with a night owl partner.

Heck, have sex all day - just not late at night...

Conclusion: Reject those 1 AM booty calls - those are good for no-one because they ruin circadian rhythm function.



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29. No pets (or partner!) in the bedroom

Pets and sleep quality

My parents always used to have a cat in their bed during their sleep time. And cats just love to hunt at night, leading to frequent wake-ups.

Animals, when kept in the bedroom, really increase the risk that you're disturbed during your sleep, either through their movement or their noise.

And you know what's really interesting?

Many pet owners don't even rate their pets as disruptive.[453] In certain circumstances, if pets are disruptive on a bed, they can lead to a decrease in sleep quality though.[454]

Plus there's another catch:

Pet dander, from animal skin, will also be emitted into the air and can lower sleep quality. If you've got breathing issues or are allergic to many substances, pets in the bedroom may become more harmful.[455; 456]

Other sources of indoor pollutants, such as dust mites, can also lower sleep quality.[457] Beware.

Pets are not the only sleep disruptors though. There's an elephant in the room:

Snoring partners and sleep quality

No one should tolerate a snoring partner consistently in the bedroom. A snoring partner will wake you up and reduce your sleep quality.

The solution is that your partner seeks treatment for the snoring. If treatment is not possible, consider the earplugs which I've mentioned before. And if earplugs don't help sufficiently, kick your partner out of the bedroom.

Your partner should never cause you sleep issues over time - that's unethical. You shouldn't lose sleep at night because you've been thought that sleeping together is "normal" - in some cases, it's not...

Seriously, sleep is that important. A snoring partner will cost you a whooping hour of quality sleep each single night.[458] You'll simply be awake more during the time you spend in bed.[459]

Conclusion: Noisy pets or partners will lower your sleep quality - remove them from the room. Beware of moving out your cat though: I've heard they plan on swift revenge...


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30. Wear the right clothing

Common sense advise right?

Unfortunately, very few studies exist on this topic. One study shows that wool clothing can be superior to cotton in helping you fall asleep quickly at lower temperatures.[460] At higher room temperatures, cotton is superior. Wool may also increase deep sleep quantity.

The key with sleeping clothing (or the absence thereof) is to use your brain. If you're spending $3,000 on a mattress but wear synthetic bedtime clothing, there's going to be a price. Linen and bamboo are great too - no synthetics allowed.

Conclusion: Get some natural fiber pajamas for when you sleep - or sleep naked.


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31. Sleep on your side or back

Many people are back sleepers. Don't get me wrong: Sleeping on your back is fine as your back and legs are supported well and pressure is distributed pretty evenly.

With a sleeping position on your back, make sure to extend your legs fully. Don't get into weird positions in which you cross your legs.

There's a downside though:

In many studies, sleeping on your back (supine) increases the risk of improper breathing. Sleep disorders where breathing play a major influence, such as sleep apnea, are highly affected by your sleeping posture.[440-442] 

Sleeping on your stomach has an even worse track record...

Sleeping fully on your stomach puts your spine into an unnatural extended position and is a frequent cause of neck and back pain.

Breathing properly becomes far more difficult in that position.

In cases you don't have a breathing problem, however, both back and side sleeping is best. Belly sleeping is possible too, at least, if most of your weight doesn't fully rest on your stomach.

Sleeping on your side is probably best as some circumstantial evidence shows that you may have improved circulation in that position.[461; 462]

Side sleeping may also clear toxins from the brain through the "glymphatic system" quicker. 

Babies also experience most slow wave sleep when they're not laying on their back.[443] Of course, babies should sleep on their back if they cannot roll to another position yet.

For adults, pillows can be used to support better posture. If you sleep on your side, you can use a pillow between your legs, for example. For a back position, you can use a pillow under your knees. The downside with using pillows is that switching positions during the night becomes more difficult.

Conclusion: If possible, side sleeping is the clear winner because of better breathing and toxin removal capacity. If you breathe properly, the back position is great as well.



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32. Add the right proteins to your diet

Got protein?

Well, eating tons of beef is not good enough...

Certain foods such as bone broth, gelatin, and collagen, contain specific "amino acids" that aid sleep quality. Amino acids are building blocks of proteins. Glycine is one important amino acid found in high quantities in bone broth, gelatin, and collagen.

(Bone broth are made by simmering bones for 2-48 hours, depending on the animal bones used. Collagen and gelatin are made from the skin and connective tissues of these animals. Fish, cow bones, and fowl can all be used.)

The benefit is that glycine improves sleep quality.[463]

Many people consume too little of that amino acid in their diets. Most foods such as muscle and organ meats and plant foods do not contain much glycine. Over time, you'll thus end up with a deficiency unless you consume bone broth, gelatin, or collagen.

Read my Ultimate Guide on Bone Broth, Gelatin, and Collagen Protein if you'd like to learn more.  

Conclusion: Add bone broth, gelatin, or collagen to your diet to up your sleep quality.



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33. Cut out excessive "polyunsaturated fatty acids"

Many people consume too many "polyunsaturated fatty acids" or "PUFAs".

Vegetable oils are a major source of these fats. Canola oil, corn oil, cotton oil, peanut oil, and rapeseed oil are prime examples of such oils (I know all these plants aren't vegetables).

Vegetable oils are often included in processed foods - the main source of their overconsumption. So if you're eating a Standard American Diet you're very likely to ingest excesses of these toxic oils.

The problem with these fats is that they contain tons of "omega-6" fatty acids. The dietary balance between omega-6 and omega-3 is important for your overall health. 

Your ancestors and traditional hunter-gatherer societies today consume between 2 and 4 times as many omega-6 fatty acids than their 3 counterpart. In modern societies, that ratio is often 10:1 and even goes up as far as 40:1.

Excessive consumption of these vegetable oils leads to metabolic disorders and disease, increasing your risk for diabetes, heart disease and cancer.[464-469] And although no specific studies on the effects of vegetable oils on sleep quality have been carried out, it's highly likely that they negatively influence sleep quality. 

PUFAs have such all-round metabolic effects that an absence of an effect on sleep quality is very unlikely.

Steer clear... 

a canola field
Canola fields: weapons of mass destruction?

Conclusion: Removing vegetable oils from your diet automatically optimizes the ratio of fatty acids in your diet. Over time, cutting out vegetable oils improve syour sleep quality.


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34. Quit napping - or optimize napping.

Napping seems extremely appetizing to many people...

And I get it...

Had a poor night of sleep? Let's take a random nap whenever you feel like it. Napping makes you feel amazing so it must be a great solution, right?

Wrong: Napping is a double edged-sword. In fact, naps can decrease your health if you don´t structure them properly.[470]

The danger is to nap whenever you feel like. That unstructured napping behavior leads to continuous re-alignment of your circadian rhythm. 

So if you're napping at 11 AM one day, 4 PM the next day, and take a 9 PM nap in front of the television the day after that, you're ruining the functioning of your circadian rhythm.

The proper way to nap is to take one at the same time every single day. And if you don't nap every day, make sure to still nap at the same time each time you do nap.

Hence, you may have a napping window between 13:00 and 13:15. If you do decide to nap, do so only within that time period. With napping, set an alarm to make sure you wake up 

Not all napping is wrong though:

Some societies still have a habit of napping to this very day, which can have huge health benefits. Mental health and wakefulness improve due to napping.[470-472]

Never nap more than once a day though. If you nap two or three times, the total amount of deep sleep you get each 24-hour period goes down.[473]

The bright side?

Elderly people who take one nap per day don't have their nighttime sleep quality impacted.[474] There's thus credence to the habit of elderly people to take a nap.

Short 15-minute naps are best for performance. You won't wake up groggy from such a nap. Nap longer than 20 minutes and you'll probably feel like you've been hit by a freight train.

That grogginess exists because you're waking up in the middle of deep sleep.

90-minute nap is a great alternative as you can go through a full sleep cycle. With a 90-minute nap, you'll wake up during or after REM sleep. If you wake up after 60 minutes in slow wave sleep, on the contrary, you'll feel less energetic.

Conclusion: Don't nap whenever you feel like it - that habit lowers overall sleep quality. Nap at the same time every day for the same length every day to reap napping benefits. 15 or 90 minute naps are best.


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35. Avoid consuming nicotine in the evening

Crazy fact:

Contrary to popular opinion, nicotine is a great performance enhancing drug that makes make your mind work better. Having said that, cigarettes are a terrible means to consume nicotine because they contain so many toxins.

The best ways to use nicotine are gums or liquid drops. These options don't contain added toxins and are far cheaper.

But there's a catch:

Don't use nicotine every single day - you'll become dependent. Nicotine dependence does decrease sleep quality, And once you're addicted, sleep quality and duration go down.[475; 478] 

If you smoke, you'll also take more time to go asleep and your breathing is impaired.[476] Additionally, REM sleep is negatively affected.[477] Even if you're young--and should be sleeping perfectly--sleep quality goes down with a cigarette addiction.[479]

And you know what's even worse?

Nicotine dependence will wake you up during the night because you're getting withdrawals. For that reason, only use nicotine sparingly...

Don't get me wrong though:

During the day, nicotine makes you more wakeful and boosts dopamine - a brain signaling compound that increases motivation, cognitive performance, assertiveness, and goal-directed behavior.

Nicotine can thus be an amazing tool for peak performance.

Morning and afternoon doses are best. Taken later in the day, such as with skin patches, nicotine will impair your sleep, especially if you're a non-smoker.[480]

The solution is thus to use quick acting nicotine earlier in the day - especially if you're one not a morning person (which holds true for many people).

A benefit of nicotine is that it doesn't stay in your system as long as coffee does - and is thus superior for boosting wakefulness.

Conclusion: If you use nicotine, use gum, skin patches or liquid drops earlier in the day. Don't use nicotine every day to avoid addiction. 


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36. Use CBD oil for relaxation and pain control

For some people who have trouble with racing thoughts or anxiety, cannabidiol or "CBD" can be a godsend.[481]

Examples of anxiety that decreases sleep quality are continuous worrying and rumination - when you should be sleeping.

If you don't have anxiety, CBD is less promising.[483] Depending on the dose, CBD can even promote wakefulness.[484]

High levels of "THC" - the pyschoactive compound in cannabis - are less promising for sleep. You'll sleep quicker but sleep quality may go down.[482]

For countering (chronic) pain and inflammation, CBD is also very promising.[700-702] 

If you'd like to learn more, read my guide on the science of using cannabis for health.

Conclusion: Use CBD oil to lower anxiety, pain, and inflammation. In other cases, CBD might be less promising for sleep quality improvement.


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37. Reset your sleep cycle if all else fails

Used about 40 of my tips and still cannot sleep?

In that case it's time to bring out the big guns. 

And you know what?

Let me tell you a little secret:

One habit that insomniacs have is shooting themselves in the foot - it's making the problem much worse. 



Many people who suffer from insomnia try to go to bed earlier to ensure they get adequate sleep that night. That habit lowers sleep efficiency because you're laying in bed even longer with even lower sleep efficiency...

And that's the opposite of what you'd want.

So here's the deal:

If you're a chronic insomniac you shouldn't focus on the coming night or even the next week. Chronic insomnia often takes some time to fix.

Forget about sleeping well tonight. It's time to start thinking about sleeping well every single night.

To win the war you must be willing to give up one battle sometimes...

The solution, in that case, is to practice "wake therapy".[485] The focus of wake therapy is increasing sleep efficiency (e.g. the amount of deep sleep you get) by staying in bed for shorter periods of time.

Beware though: Wake therapy takes several weeks to complete, and is most difficult in the earliest stages. The reason for that difficulty is that you're going to deprive yourself of sleep first so that lots of sleep pressure is built up.

The best way to build up that sleep pressure is to skip an entire night of sleep when you begin. I know that sounds difficult, and yet: The trouble is just starting.

But let's say you don't sleep at all one night...

On the second night, you're going to sleep within a strict "sleep window". That sleep window is the time you're allowed to spend in bed. A good sleep windows would be from 3 AM to 8 AM.

At 8 AM, you're going to wake up whatever it takes. Put an alarm clock in the other side of the room. Let your partner wake you up until you're standing in the kitchen. Train your cat to scratch your legs if you're still in bed at 8:05 AM.

Again: whatever it takes... 

Next, get lots of bright light exposure early in the day - preferably from sunlight.

The subsequent step is then to slowly increase the amount of time you spend in bed over the course of weeks. Yes, weeks, not days.

Every week, you can add 30 minutes of sleep time. So during the second week, you'll sleep from 2:30 to 8 AM. During the third week, that's 2 AM to 8 AM.

During all that time, you're ensuring that your sleep efficiency and quality are kept very high. Improving sleep efficiency fixes most insomnia problems...

One pointer though:

Always make sure to change the time you're going to bed instead of your wake up time. You should be able to set your wake up time wisely, such as waking up at 7 AM when you need to be at work at 9.

a man who is extremely tired and has fallen asleep inside his truck
Got an extreme urge to nap during sleep pressure buildup? Don't! Only sleep when it's nighttime.

Conclusion: If you're a chronic insomniac, reset your sleep schedule by depriving yourself of sleep for one night. Next, follow a strict sleep window of a couple of hours and expand that window by 30 minutes per week. Ensure that sleep efficiency stays high -- no more insomniac habits such as waiting to fall asleep or going to bed earlier to make up for lost sleep.


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38. Stretch, do yoga, or play with your pets

Very intense exercise late at night may lower sleep quality (or not increase sleep quality optimally). 

What you can do late at night though, is some lighter movement. Stretching, yoga, playing with your pets, gong for a walk, lightly throwing some ball with your kids, and gardening all come to mind.

Yoga can improve sleep quality, for example.[485-487] Basically, anything that breaks a sedentary lifestyle helps.[488-490] Whether you're doing some pilates or some billiard with friends, more movement fixes sleep issues.

Movement for the win...

Conclusion: Instead of watching television, do some yoga or play with your pet during the evening. Light movement improves sleep quality.


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39. Avoid or reverse obesity

Of course, you already know right now that (chronic) sleep deprivation causes obesity. The opposite is also true, however.

Being obese decreases sleep quality all by itself. If you're obese you're at much greater risk for sleep apnea, for example.[495-499] Recall that during sleep apnea your breathing frequently stops, which then wakes you up because you're short on breath.

Obesity also increases the risk for getting restless legs.[500-502] With restless legs syndrome you'll desperately want to move your legs - even when you should be asleep.

How do I know the obesity is also the cause of the poor sleep quality, and not just the other way around? Simple: weight reductions improve sleep quality.[504; 505] 

Shockingly, almost 30%+ of the US population is obese.[703] For many people there's thus lots of work still to do... 

Conclusion: If you're obese, losing weight enhances sleep quality. 


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40. Quit drinking too much fluids before bed

Nighttime toilet visits: Innocent, or not?

The latter: Waking up to pee leads to fragmented sleep. And fragmented sleep is a sign of lower sleep quality.

Contrary to popular belief, peeing at night may be a type of circadian disruption.[492] In other words, if you need to pee frequently at night, you may over-expose yourself to bright light at night, which throw many bodily processes off.

If not, bladder problems or urinary tract issues are other reasons for nighttime toilet visits.[491] Consult your physician in these cases.

The solution in other instances?

Reduce fluid intake in the evening.[493] Yet another reason to drink wine during the day...

Whatever you do, avoid having to pee frequently at night:

Nighttime toilet visits are partially responsible for the decline in sleep quality with age.[494] If cutting out fluids later at night doesn't solve your nightly toilet visits problem, consult your physician.

Conclusion: Don't drink too much during the hours before bedtime to avoid toilet visits at nighttime. 


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41. Get a weighted blanket to feel safer

Weighted blankets are the newest sleep optimization trend. A weighted blanket applies pressure to your body when you're sleeping. 

The result is that you're feeling as if you're being hugged all night long. Anxiety is the main reason many people use a weighted blanket.

And you know what?

There's quite some evidence to back these claims up. Deep pressure increases a part of the nervous system that's called "parasympathetic" - which is involved in rest and digestion.[505] 

The "rest and digest" physiology is diametrically opposed to the "fight or flight" stress response.


Children with autism or intellectual disabilities, who frequently have trouble sleeping, experience almost immediate benefits from such a blanket.[506; 507] Stress levels may also be lowered.[510]

In healthy adults too, 60% experience lowered anxiety while hugged by a weighted blanket.[508; 509] These blankets simply make you feel more safe at night. Get a weighted blanket here:

weighted blanket

Always make sure to buy a weighted blanket from natural materials such as organic cotton. 

Conclusion: Weighted blankets reduce anxiety and stress by forming a safe cocoon around your body during sleep.


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42. Curb excessive inflammation

Chronic inflammation is not so nice..

Inflammation is associated with poorer sleep. Inflammation is also related to many modern diseases, such as heart disease, diabetes, and cancer.

And ixcessive inflammation is almost always interrelated with an overactive immune system.

Don't get me wrong...

You need inflammation to fight an intruder such as a virus. When inflammation becomes chronic, however, health problems ensue.

While there's no direct evidence that lowering inflammation increases sleep quality, it's reasonable to suspect that curbing inflammation will make you sleep better.

The best way to find out whether you're affected by chronic inflammation is to use lab tests, such as "C-reactive protein", "Tumor Necrosis Factor Alpha", and "Interleukin-6".

Changing your lifestyle is most frequently the solution to chronic inflammation : deal with chronic stress, improve your diet, move more, and apply many of the sleep tips in this blog post.

Conclusion: Chronic inflammation probably affects your sleep because it is related to many health outcomes. Lifestyle improvements frequently fix the problem.



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43. Eat sufficient seafood

Seafood contains what are called "polyunsaturated fatty acids". And yes, if you remember, I just recommended you to avoid vegetable oils precisely because the polyunsaturated fatty acids they contain.

Seafood is different though, as it contains specific fats such as "EPA" and "DHA". In the right amounts, these foods will improve your health and sleep.

I therefore do not agree with the sentiment that runs in some parts of the health community in which all polyunsaturated acids are seen as damaging and need to be eliminated - regardless of circumstance.

Please keep in mind that I'm advocating for fish consumption, not fish oil consumption. About 50-80% of fish oils on the market are oxidized, meaning they have become rancid due to reactions with oxygen.[512-514]

Fresh and canned fish are thus far safer options.

The benefit of fish consumption is that you'll take less time to fall asleep.[515; 517] Fish consumption also lowers stress and improves sleep duration.[516; 517]

Conclusion: consume some (shell)fish throughout the week - such as oysters - to improve sleep quality.


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44. Use phosphatidylserine to counter acute stress

Had a rough day?

Stressed before bed?

Need a quick fix?

Consider "phosphatidylserine"...

Phosphatidylserine is a compound found primarily in (organ) meats and fish. The benefit of phosphatidylserine is that it cuts cortisol levels by 40%.[518; 519] Cortisol is a stress hormone. 

High cortisol levels lower sleep quality.[520; 521] Taking phosphatidylserine through consuming fatty fish or organ meats is your least expensive option.

Take up to 800 milligrams for the best effects. Fatty fish such as mackerel contains about 400 milligrams per 100 grams (3.4 ounces) of product.

You can also supplement with phosphatidylserine, which contains 100 milligrams per capsule (but is more expensive). Of course, nothing beats the ease of popping a few pills before bedtime...

Conclusion: Phosphatidylserine lowers acute stress which helps you sleep better. Take up to 800 milligrams to calm down before bedtime.


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45. Reprogram your mind around being in bed

Another surprise:

Ideally, your bed should only be sued for sex and sleep. Don't read or watch television in bed, as otherwise your brain is going to associate your bed with non-sleeping activities.

Being in bed should act as a cue for your body to go to sleep. If you read on your bed (unless it's 15 minutes before going to sleep), you're programming your mind to stay asleep.

Simple yet effective...

a woman who is working in bed, which is a poor sleep haibt
Working in bed? Big mistake...


Conclusion: Only use your bed for sleep and sex. If not, your brain associates bedtime with non-sleeping activities and sleep quality is impaired.


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46. Listen to relaxing music

The late Charles Poliquin recommended that people listen to Bach prior to going to bed. From a musical perspective, Bach is very slow and relaxing music that can be amazing for sleep - depending on which of his works you choose.

You don't need to listen to Bach to get sleep quality benefits though...

All music may offer a stimulus to go to sleep, block out distractions, and help you relax.[523]  As a result, music can help you fall asleep quicker and improve sleep quality.[522] The best way to use music may be to listen habitually, because it sets a pattern of expectation to your brain.[523]

The effects of music on sleep quality are really underappreciated. Even if you're traumatized, for instance, music can improve sleep quality.[524] 

Some evidence to the contrary of music's sleep-boosting-effects does exist though, as one study claims that only your perception of sleep quality goes up, instead of objective sleep measurements.[525]

Most studies do show benefits though. It's probably best to use music that's not too exciting - you don't want to get overstimulated before sleep.

Conclusion: Relaxing music may improve sleep quality. Listen to music that you personally find relaxing, independent of genre. Don't listen to Bach or Mozart if you don't like those works.


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47. Improve gut function  

If your gut is not doing well, many processes in your body will be thrown off. And while fixing gut issues can be complex, suffice it to say that common sense health intervention often help.

These health interventions include reducing stress, moving more, exercising once in a while, cleaning up your diet, etcetera.

The gut has a huge effect upon your sleep. Several gut-related conditions are interrelated with sleep quality problems. Irritable bowel syndrome, for example, is closely intertwined with sleep disturbances.[704; 705]

The same is true for inflammatory bowel disease - which is frequently more debilitating than the one I formerly described.[706-708]

No need to know exactly what these conditions entail--just remember that gut issues affect sleep. Unfortunately, I cannot give you a straightforward solution though...

Curing gut issues can be deceptively complex. Many of the strategies that improve general health, such as fixing air and noise pollution, getting sunlight, and wearing blue blocking glasses, should indirectly already improve gut health, fortunately.

In other words, apply many of the top 25 tips in this blog post and your gut issues may already heal by themselves. If not, I recommend working with an expert such as a Naturopathic doctor.

Conclusion: Gut problems are interrelated with poor sleep. Poor sleep deteriorates gut health, and poor gut health lowers sleep quality. Fixing one may solve the other problem.


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48. Get a massage

No shit Sherlock...

You could have guessed that getting a massage increases sleep quality, right?

Simply put, massages helps you relax. 

And although evidence is limited, massages may increase sleep quality. After having received a massage, people report that their sleep quality has gone up.[538; 542] Sleep duration may also go up if you receive a massage.[540]

Face massages do better than foot massages - and also cause increased relaxation.[539] I never had a face massage before though...

If you're a mother, you can also increase the sleep quality of your kids by giving them a massage.[541]

Not a lot of evidence exists, but all of it does point in the same direction...

Conclusion: Massages probably improve sleep quality--although the evidence is limited.


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49. Use an acupressure mat - especially to counter pain.

An acupressure mat contains hundreds of small spikes that will pinch into your body when you lay on it. During the first minute or three, you'll have an almost uncontrollable urge to get off the mat. After that period, however, a rush of relaxation envelops your body. Natural opioids are released then - which are endogenous painkillers.


An acupressure mat may decrease the time you take to fall asleep and increase your total sleep time.[543] 

Acupressure mats seem to be especially useful if you've got chronic pain - which prevents many people from sleeping well.[544] Another reason to use acupressure mats is if you've got trouble falling asleep.[545] 

Foot reflexology may have similar effects.[546] You can also stand on an acupressure mat to get the same effects of foot reflexology. That process may be more uncomfortable than laying on one - initially.


Standing on an acupressure mat also releases the same opioids.

Conclusion: Buy an acupressure mat online to fall asleep quicker and be less bothered by pain. With chronic pain acupressure mats may yield a pain-relieving effect. In other instances, acupressure mats help you relax.


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50. Deal with trauma such as Post Traumatic Stress Disorder (PTSD)


And has that trauma regressed into PSTD?

In that case your sleep will be negatively affected.[547-549] In fact, lowered sleep quality is one of the most important symptoms of PTSD.

Fortunately, a couple of health interventions exist regarding PSTD that many people don't know about. 

More conventional treatment examples include Eye-Movement Desentizitation Reprocessing (EMDR ) and mantra meditation. I teach the latter in my Health Foundations Program.

Don't know about these interventions? Many people don't...

So let me explain these strategies:

EMDR lets your eyes track a visual stimulus so that in the meantime your brain may reprocess the trauma and give it a place. With EMDR, you'll have decreases in negative emotions and flashbacks or visions to the trauma.[550; 551] PTSD may be resolved through EMDR.

Mantra meditation is a technique you can practice on your own - no supervision required.[552] Avoidance, depression, and bodily symptoms and decrease, while quality of life and mindfulness go up as a result of practicing mantra meditation.[552; 553] 

After some time practicing mantra meditation, many people who were initially diagnosed with PTSD no longer reach the threshold...

Other alternative treatments include MDMA, psilocybin (from mushrooms) or even ayahuasca under medical supervision.[554-556] Don't try these substances on your own though.

Unfortunately, these options have not been fully cleared by the FDA in the US, and these substances are still illegal in many countries. However, these substances are very promising in early research...

Conclusion: If you're traumatized and have PTSD, many of the sleep tips in this guide won't help you get better. Try EMDR or mantra meditation to fix the PTSD first.



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51. Simulate rocking motions withy sound

I've tested a program called "" for quite some time now, but mostly for cognitive performance during writing and studying. is music created by artificial intelligence that is specifically geared towards helping you perform better. Examples are improving your focus, relaxation, meditation, and yes, sleep quality.

In fact, the program claims 30% increases in deep sleep every single night. To put that number into perspective, after skipping a night your deep sleep percentage only increases by 10%.

The gain from is thus potentially huge.

The catch?

You'll need to wear headphones while you're sleeping. Almost all headphones emit some non-native EMF (see tip #11). You can order "sleepphones" that are wearable in bed and are wired at the same time as well though.

I'll probably test this option soon, even though it might not be the perfect long-tern solution.

If you've already got inhibited deep sleep, rocking motions will increase your sleep quality.[557; 558] In younger people, the results are less promising, however.[559; 560] Much more research is needed though, although current outcomes are great.

Let me be clear about one recommendation: Wireless audio should be avoided at all cost near your brain during sleep.

Conclusion: using with sleephones may increase your deep sleep percentages, especially if you've already got lower sleep quality.


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52. Use "Pulsed Electromagnetic Fields" - or PEMF.

Just by looking at the name you can probably already tell:

"Pulsed Electromagnetic Fields" or "PEMF" is a complex subject. 

There's truth to that statement...

The difficulty already starts with understanding PEMF. To the questions such as "what does PEMF do" or "how does PEMF work" no straightforward answer exists.

What is known is that PEMF applies EMF to your body in specific dosages that are aimed at healing.

What is also known, or rather, what can be deduced from physics theories is that the electromagnetic fields affect molecules and subatomic particles in the body. As a result, your body's physiology is affected.

But why can't PEMF be understood?


As an analogy, it's also impossible for scientist to understand how life is created out of individual chemicals - even though biologists work with life every single day.

In the same way, PEMF plainly works for certain conditions but how it works isn't fully known yet. 

What is amazing is that PEMF is effective for:

  • chronic pain - a condition otherwise poorly treatable, even though millions if not billions of people suffer from it.[561; 562]
  • neuropathic pain--which is pain in your nerves - or nerve pain[563-566]
  • joint pain, loosely called "arthritis", where functioning, pain, and stiffness all improve.[567-569] Inflammation decreases while your joints become more resilient by applying PEMF.
  • (chronic) inflammation, although that finding is based on anecdotal evidence--not on research. That massive drop in inflammation that many people experience may be the reason why PEMF is usable for potentially hundreds if not thousands of conditions in the future.

Sign you up?

Hear me out first:

One problem is that PEMF has different effects under different frequencies and intensities, making monolithic conclusions like "PEMF works" useless. Nonetheless, even the US FDA has accepted that PEMF devices can be valid for treatment in some instances.

The catch?

A problem is that lots of companies are selling PEMF devices that are overpowered in their therapeutic effect. The PEMF device I'm recommending below only emits 0.1 - 0.2% of the intensity of typical PEMF devices and can be considered very safe.

I wouldn't recommend 98% of the PEMF devices on the market today though.

Stronger does not equal better in this regard, just as a 2,000 milligram iron supplement is not superior to a 20 milligram dosage. The former supplement almost certainly undermines your health, while the latter may yield benefit, depending on your mineral status.

For home use I recommend the Micro Pulse (I'm not affiliated). That device is developed by the original inventor of PEMF and can be considered almost foolproof. The IMRS is great for full-body treatment - if you've got pain in several joints, for example.

Conclusion: PEMF is especially useful in certain situations, such as chronic pain, joint pain, and nerve pain (which all prevent sleep).


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53. Curb your allergies if you cannot breathe during sleeep

Allergies can inhibit your ability to breathe. And inhibited breathing will inhibit your sleep quality. 

If your sinuses are permanently stuffed, your sleep quality will go down and you'll spend less time actually sleeping each night.[570-572] Anxiety also increases.[573] That condition is called "allergic rhinitis".

With seasonal allergies too, sleep quality goes down.[574] Dust mite allergies? Roughly the same story.[575] 

Stopping the problem can be accomplished in two steps.

First, clear your sinuses before bedtime. The best way to accomplish that is not a nasal spray or netti pot, but to use the Bulletproof sinus rinse:


Secondly, after the sinus rinse, make sure to use an air purifier at night to ensure your sinuses won't get clogged again during the night.

Buy the Coway AP-1512HH air purifier for rooms up to 530 square feet (~50 m2), and the Alen BreatheSmart 75i for bigger rooms (or apartments) up to 1,300 square feet (120 m2). 

Make sure to active the air purifier an hour before bedtime so the device has filtered the room before you go to sleep. An active air purifier makes noise. 

These air purifiers are of great quality while still being affordable. 

Organic products such as matresses and pajamas help as well.

If these aforementioned options don't work consider antihistamines for reducing your allergy intensity. Cyproheptadine which I treat later on in this blog post (tip 61) is relatively safe.

Conclusion: de-clog your sinuses by using the Bulletproof nasal rinse and use an air purifier in your bedroom. You should be able to breathe through your nose during the night.


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54. Use cognitive behavioral therapy

Cognitive behavioral therapy (CBT) is directed at managing your thoughts, behaviors, and emotions, and their interrelation. 

As an insomniac, you may have certain irrational thoughts around sleep. Examples are thinking you need to go to bed really early to make up for poor sleep, or having the sincere identification with "being an insomniac".

You can imagine that the thought of "being an insomniac" - as a personal identity - is not conductive to great sleep quality.

CBT can help you target that belief of being, for example, or help you with relaxation training, or building a strict sleep schedule.[576] Your total sleep time and deep sleep percentages are increased, while the time it takes to fall asleep and the number of awakenings decrease.[577; 579]

More than 90 studies demonstrate that CBT is effective.[578] CBT should mainly be used by chronic insomniacs, but does involve many of the steps I've already laid out in this blog post.

Conclusion: If you're a "chronic insomniac", medical professionals can help you with Cognitive Behavioral Therapy to change your thoughts, behaviors, and emotions around sleep. CBT improves certainly sleep quality.


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55. Ventilate the bedroom to remove CO2

For some people fresh air does wonders, for others it's highly problematic (due to allergens).

CO2 is the reason you'd want to ventilate your bedroom in the first place. In nature, CO2 levels are located at ~400 parts per million. In bedrooms those CO2 levels can approximate 4,000 parts per million potentially - a 10-fold increase.


Each time you exhale you emit CO2. The oxygen you inhale is paired with carbon, which becomes CO2

High CO2 levels decrease sleep quality.[580] Respiration also becomes worse with higher CO2 levels.[581]

A balance needs to be struck between opening up your windows (to let CO2 leave and new oxygen come in) and bringing in (and breathing in) polluted air.

The easiest way to accomplish that feat is to keep a bedroom windows slightly open, and place an air purifier nearby to filter the incoming air. Make sure to open a window as far away from your bed as possible, as air purifiers can be noisy.

an opened window for ventilation
The best anti-CO2 buildup technology in the world...


Conclusion: Ventilate your bedroom once in a while to avoid CO2 buildup. High CO2 levels lower sleep quality.


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56. Don't use an alarm clock

If you need to use an alarm clock to wake up in the morning, you know for certain that you're building sleep debt.


Simple: If the alarm goes off you know you could have slept longer. Each time you thus wake up with an alarm clock means that you're sleep deprived to some extent that day.

The solution is to plan your sleep better. If you know that you should be waking up at 7 AM, and that you need 8 hours of sleep, you ought to be in bed at 11 PM.

If you're not sleepy at 11 PM, then double check whether you're wearing your blue blocking glasses after sunset (see tip 4). 

If you're following most of the tips in this guide, and you're still not sleepy at 11 PM, you might be a night owl. In that case, negotiate with your boss whether it's possible to start your workday later and leave later. Your boss will thank you for the higher productivity you'll experience.

Either way, good sleep entails not having to wake up with an alarm.

Conclusion: Every time you use an alarm clock to wake you up you've underslept. Get in a position in which you don't need an alarm anymore.


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57. Fix your thyroid

The thyroid is an organ at the front of your neck. If that thyroid is not functioning properly, and doesn't emit sufficient levels of thyroid hormones such as T3 and T4, your sleep is also impaired.[583]

In rat studies, a slowly working thyroid (hypothyroidism) also leads to more wakeups during deep sleep.[584]

In humans, the time spent in deep sleep is also reduced while REM sleep is not.[585] High TSH levels - a hormone often elevated in hypothyroidism - is also associated with lower sleep quality.[586]

Sleep apnea may also be directly caused by hypothyroidism.[587; 589] The reason is that hypothyroidism reduces respiratory function of your lungs and other tissues.[588] 

How to know whether you're affected?

Hypothyroidism symptoms include poor skin quality, holding onto more fluids (especially in the face and neck), fatigue, insensitivity to cold, poor digestion (especially constipation), and poor mood and brain function.

Fixing thyroid issues is complicated and cannot be treated in this blog post. I'll write about the topic in more detail in the future.

Conclusion: If your thyroid is not working properly you'll get less deep sleep per night. Get your thyroid lab tested if you suspect hypothyroidism.


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58. Wind down before you go to bed

This tips is really common sense but I'll mention it anyway: don't plan on any exciting activities an hour before bedtime.

The hour before you go to sleep should be targeted towards resting. If you're still working just before bedtime or cleaning the house you're making a mistake. Your body isn't settled into relaxation in these cases.

Conclusion: Start relaxing an hour before bedtime to wind down.

fireworks display, signifying an exciting time before bed, which counteracts deep sleep
Not the best state of mind before you're going to sleep


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59. Supplement with theanine

Theanine is a compound in tea. Adding theanine to caffeinated beverages makes them less stimulatory and jittery, for example.

But theanine can also help you sleep. In children with ADHD, 400 milligrams of theanine increases both sleep quality and efficiency--but not the time it takes to fall asleep.[613]

In adults too, theanine specifically reduces anxiety while not being sedative.[614] Sedatives can be addictive and make you drowsy during the day.

Theanine's relaxing effects are far-reaching:

If you're depressed, for instance, theanine can lower anxiety and sleep disturbances.[615]

Buy theanine capsules or powder. You can also consume green tea that's low in caffeine (and thus contains proportionally more theanine).[612] Green tea with more caffeine leads to worse sleep outcomes than low-caffeine variations.

It's probably best to use theanine as a "secret weapon" for stressful days, because your body might adapt to taking the substance chronically.

Conclusion: Theanine can lower anxiety and improve sleep quality and is best taken on psychologically stressful days. Combine with aforementioned supplements such as phosphatidylserine for an even stronger effect.


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60. Consume adaptogens to lower stress

Adaptogens are cheap yet effective for improving sleep. The main role of adaptogens is to normalize stress levels, exemplified in hormones such as "cortisol".

Either too high or too low stress levels are thus moved towards the mean with adaptogens. Rhodiola rosea, ashwagandha, and Korean ginseng all lower stress and anxiety, for example.[591-595]

While no direct evidence exists that these substances increase slow wave sleep, what is known is that stress inhibits slow wave sleep quantity.[596; 597] Lowering stress should thus increase the amount of deep sleep you get.

Grab some adaptogens and lower stress instantly. For the best effects, cycle these compounds on an off throughout the week.

Conclusion: Adaptogens, when taken during the day, may indirectly improve the amount of deep sleep you get by lowering stress.


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61. Use cyproheptadine to counter nightmares

Nightmares and want to relax? Try cyproheptadine. The substance puts you in deep rest, lowers anxiety and stress, and decreases the propensity for nightmares.[597; 602] 

That approach can be really helpful if you've got PTSD or another disorder that's often paired with extreme nightmares.[599; 600]

Cyproheptadine is also an anti-histamine, and may thus help opening up your nose before bedtime.

Possible side effects include hunger and suppression of growth hormone at night.[598] I'd thus be careful with long-term use.

In many countries you can buy cyproheptadine without a doctor's prescription though...

Cyproheptadine, next to being an anti-histamine also puts you in deep rest.


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62. Include enough calcium and potassium in your diet

Many people are under consuming minerals. Zinc and magnesium are two minerals I've considered earlier, and now it's time for calcium and potassium.

Shocker: 98% of Americans are consuming too little potassium.[602] About half the world's population - 3.5 billion people - are at risk for calcium deficiency.[603]

You need both minerals to sleep properly, however. Some evidence exists that calcium plays a role in regulation of the nervous system during sleep.[604; 605] 

For potassium that link is stronger. The reason is that potassium plays a major role in stage 2 and slow wave sleep.[606; 608] If you've got hypertension, for example - which is interrelated with potassium deficiency - your risk for poorer sleep quality also goes up.[607]

Potassium under-consumption is thus not a side issue that can be ignored...

Fruits and vegetables contains the highest amount of potassium per calorie. Most other whole food sources are great for upping your potassium intake as well. Avoid processed foods if you want to consume sufficient potassium.

For getting sufficient calcium milk products are best. If you cannot drink milk or do not drink milk, bone meal is the easiest option (that's also great for people on the Paleo diet).

picutre of a cow who is looking at you
Producers of the best calcium products in the world...

Conclusion: Although speculative, minerals like calcium and especially magnesium may be necessary for promoting more slow wave sleep.


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63. Ensure you're not iron deficient.

Iron, another mineral that you may know of...

Iron deficiency lowers your sleep quality. Fortunately, not that many people are iron deficient in the developed world today. 

For the developing world that story is completely different though. But as most of my readers stem from the developed world, I've placed this tip somewhere last.

Iron deficiency does not just cause depression and anxiety, but also lowers sleep quality independent from that depression and anxiety.[610]

The pattern of brain wave activity during slow wave sleep is specifically altered during an iron deficiency.[611]

For children iron deficiency is especially dangerous. The reason is that the brain doesn't recover an optimal sleeping pattern for years after the deficiency has been fixed.[612]

Parents, feed your kids well...


Shellfish and (organ) meats are the best iron sources. Red meats are generally better than whites ones. Plant foods are sub-par sources of iron that is highly absorbable. At the minimum, include some red meats and shellfish into your diet every week.

Conclusion: Consume sufficient dietary iron from meats and shellfish to avoid iron deficiency. Iron deficiency directly lowers sleep quality.


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64. Try valerian and passionflower

These two compounds are no wonder drugs but they can help in certain instances:


In animal studies, passion flower increases both slow wave sleep as well as total sleep duration - even at the cost of REM.[666] The mechanism may be a change in the circadian rhythm, while inducing sleep earlier than normal.[667]

Anxiety may also be reduced.[668] In humans, that anti-anxiety almost certainly exists as well.[669] As a result, you'll probably experience increased sleep quality.[670]


Valerian is kind of similar. Fortunately, valerian has been more extensively studied than passion flower--although study quality is still not spectacular.[671-673]

Two out of three studies conclude that sleep quality improves without adverse effects with valerian supplementation.[671-673]

You can get valerian and passion flower supplements online. For the best results, cycle on and off.

Conclusion: passion flower reduces anxiety, and both valerian and passion flower may improve sleep quality. These supplements are nothing magic but just another tool in your toolkit... 


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65. Transcranial Direct Current Stimulation (TDCS)

Just when you thought therapies couldn't get any weirder there's TDCS. 

And contrary to what the name implies, you're either using a direct current (DC) or an alternating current (AC) with TDCS. Both currents can thus be applied to your brain (in the right context).

Fortunately, tons of research has been coming out on TDCS the last few years. When used correctly, TDCS is safe, inexpensive, and well tolerated.[625]


With an alternating current (AC), slow wave sleep EEG function of the brain can be accentuated, leading to better sleep quality.[623]

Specifically, TDCS can lead to an ~10% increase, and 20% increase in the propensity to move from NREM stage 2 to 3.[628] The quality of the deep sleep may also improves - these activity levels decline with age but TDCS reverses that pattern somewhat.[629]

In healthy sleepers, TDCS seems to have less of an effect - total sleep time is not increased for instance.[630]

That manipulation of sleep through TDCS can have all kinds of brain-related consequences, such as improving different types of memory.[621; 622; 626; 627] Some studies contradict that finding though.[624]

The biggest problem with TDCS is using the therapy at home in setting the right parameters. Due to the promising research that is emerging on this field, however, I do think simpler consumer options will become more popular in the future.

You can already buy TDCS online right now...

Conclusion: TDCS is very promising for increasing slow wave sleep quantity and quality at nighttime, especially for when you're getting older. With good sleep TDCS shows little promise in promoting more deep sleep right now.



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BONUS: 66. Phenibut

If all else fails, there's phenibut. Some nights you simply cannot sleep well due to extremely stressful events that day.

The solution, then, is to strategically use this compound. Phenibut acts on the GABA receptors of the brain, which are involved with relaxation.[616] The result is a radical decrease in anxiety.

While the effects of phenibut on sleep quality have not been directly studied, other drugs that affect the GABA receptors do increase sleep quality.[618-620]

There must be a catch, right?


The problem with phenibut is that it's extremely addictive.[617] I therefore recommend taking this compound one every week at the maximum.

The upside?

You can get the stuff dirt cheap on the internet without a doctor's prescription. Only use if you're not prone to addiction...

Almost nearing the end of this deep sleep series...

Conclusion: Have some phenibut on hand for the very worst days. The stuff makes you extremely relaxed and very well able to sleep almost independent of circumstances. Don't use more frequently than once every two weeks.



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BONUS: 67. One tip to rule them all:

Want to use all these tips far more effectively? Sign up to my "one tip to rule them all" below:



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BONUS: 68. Seek help of medical sleep specialists

If all of my tips haven't fixed your sleep issues, then it's time to consult a medical professional. 

That professional might advise you to keep a sleep diary, filling out questionnaires, order lab tests, or invite you for an over night sleep study. Let's consider these options:

  • In a sleep diary, you're tracking when you're going to sleep, how often you wake up, when you wake up, how tired and stressed you are during the day, etcetera. If you've been following my tips you should already have insight into this domain.
  • Questionnaires give medical professionals insight into your sleeping patterns.
  • Lab tests can include genetic testing for your chronotype, diagnosing a potential thyroid problem, and so forth.
  • During a sleep study you're invited for an overnight stay in a sleep lab. You'll have electrodes attached to your body, which measure all kinds of health variables. For instance, your breathing frequency an depth, possible snoring, movement during the night, heart function, brain waves (with an EEG), oxygen saturation, can all be measured. That data yields insight into your sleeping pattern.

Again, by all means, if the tips in this guide have not helped you then seek out professional help. 

a woman who is napping on a cushion
Is this your life after implementing most of the previous 64 tips? Then tip 65 entails participating in a sleep study.


Possible other options:

In the future I'll probably expand this guide even more. Progesterone and DHEA supplementation, melatonin supplementation with age, genetic analysis, sleeping on the floor or in a hammock instead of a bed, and many more tips will be added.

In fact, if I dug deep into the science another 30,000-word blog post could be created on additional sleep quality tips. I nonetheless hope you're realizing that sleep optimization is more complex than you realize.

Oh yeah, one more thing:

Congratulations. You've read all the way through and can call yourself a "sleep expert" now. You'd even be wise to share this information with your friends, colleagues, and family. Only with your help can the sleep revolution fully finish...

And there's one last step to take:

Conclude and take the 30,000 foot view...

Section 5 summary: 

Slowly work your way down with these 65 sleep tips. Start with the top ~25 - which are most important, and work your way down. With these tips you should be able to maintain sleep quality as much as possible - even into old age.


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I've given you 65 tips to improve deep sleep quality.

But what's the significance?

Well, if you want to age well, improve performance, lead a happier life, or be healthier overall, sleep must be prioritized.


Nature fights tooth and nail to maintain sleep whatever the situation. Across millions of species, sleep hasn't been successfully eradicated in evolution.

That fact alone should tell you how fundamentally valuable sleep really is. And yet, millions (if not billions) of people are walking around sleep deprived every day.

That's weird...

Technology has changed society so dramatically since the 19th century, that humans haven't caught up yet. Since that time, your great grandparents and great-great grandparents started living their lives the way technology forced them to live. 

That complacency is a terrible mistake. The intuitive following of the laws of nature - such as day and night cycles - was replaced by human hubris. And that hubris slowly became our undoing, beyond conscious control.

Sleep began to be seen as an efficiency, a period to be eliminated. Great minds such as Thomas Edison - the inventor of the light bulb - ironically thought that future minds would sleep less and less in the future.

Nothing could be further from the truth...

The great minds of tomorrow will have optimized their sleep quality.

Sleep is not something that should occupy your mind at night - planning for proper nighttime sleep starts during the daytime. 

The best sleep beings at the beach. Why? Sunlight exposure, de-stressing, gounding, fresh air, serene sounds, other people, and the relaxing nature of water nearby programs you for the best sleep ever:

a relaxed woman at the beach

You deserve the best...

Start upgrading your life by prioritizing your sleep today.

*Post can contain affiliate links. Read my affiliate, medical, and privacy disclosure for more information.

Author: Bart Wolbers. Bart finished degrees in Physical Therapy (B), Philosophy (BA and MA), Philosophy of Science and Technology (MS - Cum Laude), and Clinical Health Science (MS).

For other blog posts, see:

Beat Insomnia Tonight: The 50 Most Remarkable Sleep Quality Tips

Red Light Therapy: A Fountain Of Eternal Youth And Health?

Rethinking Magnesium: Why You're Deficient And Need To Supplement (Quick Fix)

How Noise Pollution Slowly Degrades Your Health Without You Even Noticing (+Simple Solutions)

Mindfulness Meditation: Paradise For Your Daily Life?

For further reading on deep sleep, consider:

  1. CDC: Sleep basics
  2. Systematic review: Health consequences of sleep deprivation, specifically with a metabolic and inflammatory perspective.
  3. Systematic review: Neurophysiology of wakefulness.
  4. Systematic review: How (prescription) durgs affect sleep.
  5. Systematic review: Sleep quality developments during aging.
  6. Mechanism of slow wave sleep
  7. National Sleep Foundation: Dangers of drowsy driving - a common side effect and danger of sleep deprivation
  8. American Academy Of Sleep Medicine: Sleep disorders
  9. Information about specific sleep disorders such as narcolepsy; sleep apnea; circadian sleep disorders; restless legs
  10. Very Well Health: Sleep better in 30 days course.
  11. Sleep Junkies: Sleep Tracking in 2019
  12. The history of hunter-gatherer sleep patterns; Smithsonain on hunter-gatherer sleep patterns.
  13. Psychology today: chronotypes and anti-predator behavior
  14. Scientific American: Why did sleep evolve?
  15. New York Times: The evolutionary history of melatonin; Evolution and changing sleep habits.

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