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Why We Sleep (Unlocking the Power of Sleep and Dreams)

Matthew Walker · 25 HN comments
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Amazon Summary
“ Why We Sleep is an important and fascinating book…Walker taught me a lot about this basic activity that every person on Earth needs. I suspect his book will do the same for you.” —Bill Gates A New York Times bestseller and international sensation, this “stimulating and important book” ( Financial Times) is a fascinating dive into the purpose and power of slumber. Sleep is one of the most important but least understood aspects of our life, wellness, and longevity. Until very recently, science had no answer to the question of why we sleep, or what good it served, or why we suffer such devastating health consequences when we don't sleep. Compared to the other basic drives in life—eating, drinking, and reproducing—the purpose of sleep remained elusive. An explosion of scientific discoveries in the last twenty years has shed new light on this fundamental aspect of our lives. Now, preeminent neuroscientist and sleep expert Matthew Walker gives us a new understanding of the vital importance of sleep and dreaming. Within the brain, sleep enriches our ability to learn, memorize, and make logical decisions. It recalibrates our emotions, restocks our immune system, fine-tunes our metabolism, and regulates our appetite. Dreaming mollifies painful memories and creates a virtual reality space in which the brain melds past and present knowledge to inspire creativity. Walker answers important questions about sleep: how do caffeine and alcohol affect sleep? What really happens during REM sleep? Why do our sleep patterns change across a lifetime? How do common sleep aids affect us and can they do long-term damage? Charting cutting-edge scientific breakthroughs, and synthesizing decades of research and clinical practice, Walker explains how we can harness sleep to improve learning, mood, and energy levels; regulate hormones; prevent cancer, Alzheimer’s, and diabetes; slow the effects of aging; increase longevity; enhance the education and lifespan of our children, and boost the efficiency, success, and productivity of our businesses. Clear-eyed, fascinating, and accessible, Why We Sleep is a crucial and illuminating book.
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Late to the party but going to post anyways...

So, recent R&D into sleep tech has come along ways in the past 20 years. Basically research has shown that during nap/sleep cycles our brain moves around memories (from short-term to long-term and prioitization) and connections between memories. Also, this process optimizes information in the brain to make the access faster and more efficient thus providing opportunity for neuralogical advanced thought sessions given the datasets after a nap/sleep session.

Some basic take aways include +20% memory capacity per 8-hour sleep cycle and longer un-interrupted access to memory collections. It's also been shown that it's possible to tag the day's memories and then prioritize them during the next nap/sleep session. Significant results have shown that groups that take 30-minutes nap have stronger memory capacity versus groups with no naps.

The face of the R&D seems to be Matt Walker - PhD Brit with intense accent - you've been warned!

TL:DR - The brains basically recharges AND rewires during nap/sleep sessions.

Here's the links:

podcast: The Matt Walker Podcast


> They're fine if they go to bed early.

They're not. This ignores diverging chronotypes. I suggest you read up on the science around sleep before commenting on whether "they're fine".

Obviously we can't control this, so I see no evidence that "chronotypes" are formed by nature and not by nurture. Lots of other stuff we do is influenced by our social structure and we could probably fix most teenagers and young adults by changing that.
There is no value in messing up your sleep pattern.

It’s self-discipline theatre.

We used to need early rising when we milked cows and hunted at dawn.

But now we primarily need sharp minds and being awake at dawn has no special benefit.

I say this as an early riser.

> Obviously we can't control this, so I see no evidence that "chronotypes" are formed by nature and not by nurture.

Here’s why: The Hadza are hunter-gatherers whose lifestyle is very similar to that of early humans.

The observations were found in people with lifestyles that represent that of early humans. What part of nurture would affect those people? They have no concept of a clock...

As stated above, I'm a night owl myself and tend to have a pretty off kilter sleeping schedule. A bunch of things have contributed to that - I've got ADD and have been on stimulants for most of my life, I worked as a game dev for a few years which involved months of overtime where we'd often work 12hrs three times a week that played absolute hell with my sleeping schedule and still plagues me to this day - lastly, I'm light sensitive, I can't comfortably see and operate in full daylight.

I can't say for certain where my night-owlish self comes from, but it predates taking stimulants and working at a game dev company - so maybe it's a side effect of light sensitivity or maybe it's a neurological thing... or maybe it's just a natural clock thing.

I think the science around blue-light-blocking glasses is being seriously questioned (and in my own experience, detailed in my other comment, most of the models on the market don't have any discernible effect).

But I believe the science does indicate that circadian rhythm regulation by the human body is strongly influenced by external light, and specifically blue light.

This doesn't mean that "blue light blocker" glasses work, though. And most of them don't even actually block blue light, they just diminish it somewhat.

I read the book Why We Sleep, by UC Berkeley professor and sleep researcher Matthew Walker, and that is one of the topics covered in the book. (In addition to sleep being fascinating topic generally that book has a number of practical suggestions for better sleep which have helped me, such as setting your bedroom temperature colder and using blackout curtains), so I recommend it if those things are of interest.


I can't find the link now, but when asked about things he has changed his mind on since writing the book, Dr Walker says he highly over-stated the impact of blue light.

Yes, circadian rhythm has an impact, and it is influenced by light, but that isn't the only influence.

Dr. Huberman says it is actually the amount of light you get early in the morning, which sets up your sleep cycle later in the day.

Required additional reading:
Hmm that is indeed very interesting. I’ll have to read through it more thoroughly (and Prof. Walker’s subsequent errata/responses) to make a judgement about whether the errors cited rise the the “actually, fuck that book” level or not.

Thanks for the pointer, though, I was not aware of such criticism.

The criticism of Dr Walker are often harsh. He made the subject accessible to the general public. He did make some poor connections, and drew conclusions that maybe aren't completely agreed upon across the sleep community, but the anger against him and people calling him a charlatan, I believe, is misguided.

I've found when confronted with new evidence, or evidence of his errors, Dr. Walker has been very good about owning up to his mistakes.

Yeah, I am willing to give him the benefit of the doubt, because the very first time I heard from him (in an interview series in the Waking Up meditation coaching app), he talked about various mistakes and regrets about his book, or things he wished he’d done differently.

Blue light didn’t come up then, but talking about the stark alarming tone he sets in the book, about what the detrimental effect of not sleeping well can be on your body.

He said that he later realized how unhelpful this is for people who have real insomnia problems, and can’t sleep even though they do understand and take it seriously.

So my first impression of him was of a guy that is willing to own up to his own mistakes (partly why i bought his book).

My very TLDR summary: The older people at the firm had the same experience coming into this business. So they expect every new comer to behave the same. Its that simple. Doctors do that with residents which I think is more concerning. I read about it in a book called why we sleep[1] about sleep. [1] -
I know this book gets posted anytime something sleep related comes up... but I still find it underrated.

'Why We Sleep'[0] has changed my sleeping habits for the better and I wish everyone had the chance to read it. It's like a manual explaining how your body works 1/3 of the time you're alive.


"“Why We Sleep” Is Riddled with Scientific and Factual Errors"
Thanks for the link. I love the book and have recommended to many friends, but also felt the lack of scientific sources somewhat disappointing.
I found the statistics in Dr. Matthew Walker's Why We Sleep [1] pretty compelling.

Starting an hour layer improves SAT scores:

One of the first test cases happened in the township of Edina, Minnesota. Here, school start times for teenagers were shifted from 7:25 a.m. to 8:30 a.m. More striking than the forty-three minutes of extra sleep that these teens reported getting was the change in academic performance, indexed using a standardized measure called the Scholastic Assessment Test, or SAT.

In the year before this time change, the average verbal SAT scores of the top-performing students was a very respectable 605. The following year, after switching to an 8:30 a.m. start time, that score rose to an average 761 for the same top-tier bracket of students. Math SAT scores also improved, increasing from an average of 683 in the year prior to the time change, to 739 in the year after. Add this all up, and you see that investing in delaying school start times—allowing students more sleep and better alignment with their unchangeable biological rhythms—returned a net SAT profit of 212 points. That improvement will change which tier of university those teenagers go to, potentially altering their subsequent life trajectories as a consequence.

(This is one example, that has been replicated many times, he covers more in the book.)

It saves even saves lives:

Yet something even more profound has happened in this ongoing story of later school start times—something that researchers did not anticipate: the life expectancy of students increased. The leading cause of death among teenagers is road traffic accidents, and in this regard, even the slightest dose of insufficient sleep can have marked consequences, as we have discussed. When the Mahtomedi School District of Minnesota pushed their school start time from 7:30 to 8:00 a.m., there was a 60 percent reduction in traffic accidents in drivers sixteen to eighteen years of age. Teton County in Wyoming enacted an even more dramatic change in school start time, shifting from a 7:35 a.m. bell to a far more biologically reasonable one of 8:55 a.m. The result was astonishing—a 70 percent reduction in traffic accidents in sixteen- to eighteen-year-old drivers.

To place that in context, the advent of anti-lock brake technology (ABS)—which prevents the wheels of a car from seizing up under hard braking, allowing the driver to still maneuver the vehicle—reduced accident rates by around 20 to 25 percent. It was deemed a revolution. Here is a simple biological factor—sufficient sleep—that will drop accident rates by more than double that amount in our teens.

There's more reasons, like improving attendance and decreasing drug/alcohol use, but these are the ones that stuck out to me. There was another statistic that I can't immediately find a quotation for that was pretty mind-blowing for me, which was that in university, the difference in performance in controls and students who started class an hour later was equivalent to the difference between controls and students who had a professor a standard deviation above the average. They even showed that this was dose dependent (an extra hour later had more effect). I think it's pretty incredible, considering the skill gap between an average professor and a great one, that simply taking a class at a 10am instead of 8am can increase learning so much.


Why We Sleep [1], by Matthew Walker, PhD.

Page 92:

"Adolescents face two other harmful challenges in their struggle to obtain sufficient sleep as their brains continue to develop. The first is a change in their circadian rhythm. The second is early school start times."


"... the circadian rhythm of a young child runs on an earlier schedule. Children therefore become sleepy earlier and wake up earlier than their adult parents. Adolescent teenagers, however, have a different circadian rhythm from their young siblings. During puberty, the timing of the suprachiasmatic nucleus is shifted progressively forward: a change that is common across all adolescents, irrespective of culture of geography."

It goes on to explain why this is the case, and the impact on your sleep schedule.

Also page 308-16 there's an entire chapter on Sleep and Education, and the problem of schools starting progressively early, mostly for the convenience of society at large, rather than a net benefit of the kids.

The book has been largely discussed on HN before; definitely worth reading.


I just came here to see this citation :)
Nothing in that contradicts what i wrote, it supports it.
100% this - I read the Why We Sleep book earlier this year and this quote immediately came to my head when I read this news.
You could read Walker’s 2017 book, Why We Sleep,

He’s the director of UC Berkeley’s Center for Human Sleep Science, so you could also look up his lab’s scholarly publications

I'm not sure an entire book would constitute a "too long; didn't read".
Unless the original text is the whole body of sleep research. In that case a popsci book is a nice TLDR.
A book is considerably more browsable than a 6 hour audio recording.
This reminds me of a section of the book "Why we sleep"[1] that said similar techniques could enhance an older persons sleep quality. (I don't know the title of the study unfortunately.) It looks like this is an exciting area of research right now.


While alcohol will help put you to sleep (so will a concussion) it inhibits the restorative function of sleep. (1,2,3)

I’m all for the hedonistic rationalization for alcohol. We all need a release. But it is disingenuous to say alcohol has any positive effects beyond that. It is no different than sugar in that regard. My Saturday night cheat meal is filled with both, and I always look forward to it. But I don’t try and pretend that it’s in any way good for me (beyond psychological).

To that end, I completly agree with you that there are plenty of people who enjoy a few drinks without any real damage. I'm saying classify alchohol for what it it. The tobacco and sugar (4,5) lobbies love to pretend that they are something which they are not to sway public opinion. That is dangerous to society.

1. 2. 3. 4. 5.

Sleeping has a huge impact in procrastination. The lack of sleep translates into an hyperactive amygdala (which has a big influence in processing emotions and impulses) and an under-active frontal cortex (which influences our rational thinking, etc) [1]

According to my experience, a good night of sleep is the best cure for procrastination, sadly, our current society don't optimize for sleeping well.



Hm. Not convinced of the link between the two. The article is arguing that procrastination is the proactive delay of making a hard decision to the detriment of our mental wellbeing. A good night's sleep isn't necessarily going to make you want to confront that decision.
Research has shown that there is absolutely a connection between sleep and procrastination, with low-quality sleep increasing the likelihood that people will procrastinate, particularly among people who are naturally prone to procrastination.

This is attributed to the fact that sleep is crucial when it comes to replenishing the mental resources that you need in order to self-regulate your behavior effectively.

This article contains a summary of research on the topic which came out recently:

I agree. Beeing motivated but without a good sleep it's like a runner showing up to the race with a broken leg.

I'm sure there are many types of procrastinating but this is the most common for me.

I have the opposite experience. As soon as I started to sleep for more than 8 hours, I basically stopped doing something other than work and sleep. Just do not feel the need.
A person should go to bed earlier then. Can't sleep? Then get some exercise and clean up their diet. At some point a person has to take control of their impulses.
1. Why assume the person should sleep earlier? I, personally, am better if I sleep at a much later shift than if I sleep earlier. Not just that, but society works differently than my natural body clock. I can fudge some with good sleep hygiene and attention to waking times, but never enough to make 6-7am natural. Simply "check to see if you are sleeping enough" is a bit better than "sleep earlier". (I don't wake early since I don't have to).

2. Diet doesn't really help sleep. A healthy weight can sometimes help one sleep. Not having heartburn can help one sleep. Otherwise, though, it doesn't do much.

3. Exercise. I know this helps some folks, but I do get activity most days. This does not equate into mroe sleep.

4. An entire boatload of other things can affect sleep, only a few of which has to do with impulses. For example, it is spring and the sun wakes me. This is a temporary thing: I'm in Norway, and the sun is starting to come in the bedroom window. It'll shift soon enough. Health problems exist: Everything from aches and pains to chronic diseases of all sorts to sleep disorders. Sure, a few are lifestyle based, but many of those can have multiple causes. Sleep apnea, for example, is often tied to smoking and/or weight, but can be caused by a slew of other things as well (nerve damage, for example, or issues with one's nose and throat).

Diet absolutely helps sleep, certain foods make it easier for you to sleep [1]. Exercise also helps with sleep [2]

[1] [2]

This is such a simplistic view. Tell that to the doctor in residency.

The US work culture sure doesn’t care about you getting rest.

The OP said society, not a doctor in residency. The average amount of TV consumed in the US per day is somewhere around 5 hours. How much time do people spend on Facebook or Twitter every day?

Yes, people work a lot and some of those people have terrible commutes. But, that is generally not society as a whole. Just because there are exceptions does not invalidate that the simplistic view is the right answer for most.

I don't know anybody who has time to watch 5 hours of TV per day. Do you?
Most people don't track there sleep well-enough to know its their sleep which affects their willpower.

Ignorance does not seem like a character flaw. Ignorance of oneself even, which is what we're often talking about.

I've spent at least 11 years working to "take control of [my] impulses" when it comes to sleep and other negative behavioural patterns.

I've explored everything that the mainstream and heterodox medical/psychological bodies of knowledge can offer up, including exercise, diet and a vast assortment of approaches, some of which you can imagine and some of which you can't imagine.

I've had solid success, eventually, but it's taken a huge amount of effort over a long period of time. And I'm in a pretty good position regarding finances, family support and work flexibility.

Others aren't so lucky.

You should tone down the barbed insistence that people should just decide to change. This stuff is hard, and actionable solutions and societal support are very hard to come by for many people.

I'm not so sure. I think poor quality sleep and proscrastination are a symptom of not wanting to do something.

Poor quality sleep never got in the way of me doing the things I wanted to do. Whether it is prepping for a field trip I was excited about or waking up in the middle of the night to watch a livestream of esports game or anything I was interested it. It's only chores, jobs or studying for something I wasn't interested in that I always put off til tomorrow. And things like meetings at works I wasn't looking forward to always contributed to poor quality sleep.

Rather than being the cause, I suspect poor quality sleep is a symptom.

Highly recommend Spark! If you like the topic of Sleep, check out Why We Sleep by Matthew Walker:
I have my eye on Why We Sleep and want to read it soon. I did ask Matthew Walker once about the fact that he says you cannot pay of Sleep Debt whereas William Dement (Promise of Sleep) says you can pay off up to 1-2 weeks but no more. In my experience, I can pay off some sleep debt in a week but it levels out after that.

I haven't heard back on that, probably should message him outside of Twitter, but was hoping for a public dialogue.

I am just finishing reading the fantastic book Why We Sleep [1], and as in so many well-meaning studies and articles, I can't help but feel like this effort is misguided. Just like an addict cannot accept help until they want it, I don't see how "adjusting" work schedules for those who don't even understand their own biology can possibly be helpful.

I've ALWAYS considered myself a night owl. I'm still not sure I'm not. But I've spent the past year rising earlier than I'm used to, and the past 7 months rising even earlier than that due to an enforced carpool with my wife. For the first time in my working life, I HAVE to be awake at a certain time (incidentally, far earlier than I'm used to). Instead of snoozing for an hour, I bolt from bed far earlier than I want to. I go to sleep marginally earlier. But my routine is regular I'm happier. I feel better. I feel healthier. I started reading the book and am acutely interested in tuning my sleep times to make this work even better.

Maybe I've never been a night owl. Maybe I've just had horrible sleep habits. Or maybe I AM a night owl, and I'd be even better off than I can possibly imagine, if I take all of these habits and processes and move them later in the day.

But I just feel like you can't possibly know if you're a morning bird or a night owl until you're already, consistently, religiously, getting enough sleep every night, on a consistent sleep/wake schedule.


> For the first time in my working life, I HAVE to be awake at a certain time

This one on its own is (for me at least) far more important than the exact time when you go to bed/ wake up. Having the steady rhythm of life gives you the feeling of control and reduces anxieties, and you'll almost certainly feel better after some time. I used to work nightshifts in the data-center for a while and I would sleep during the day and it worked for me just fine. On the other hand while in the army I was getting up really early (4.30am every morning) every day, and again it was working great for me (after some adjustment period of course). So two completely opposite schedules, but both very strict and regular over the 6+ months period, and both made me feel very energetic and healthy. However, as a student I also briefly had a job with the weirdest floating schedule where you'd one day work a morning shift, then in the afternoon next day, then a nightshift, and then you'd have a free day afterwards. That one was a disaster, I just couldn't get used to that schedule. I gained 20 kg in 6 months and felt sleepy and tired all the time. Routine is a good thing.

Exactly agreed. Having a schedule you are obligated to comply with may outweigh the benefits of optimizing your sleep schedule, at least for some people. I think the hype around sleep is justified, but we fall into the trap of optimizing around a single variable (and not adequately considering the multivariate system). Rhythm and schedule is important too.
> Instead of snoozing for an hour,

I've never understood the snooze button. Either it's time to get up or it's not.

I find it INCREDIBLY difficult to wake from sleep. As do many others, apparently.

Getting enough sleep is a first step, but we know most people do not -- so very few are in the great position you are to treat it as a 100% conscious choice to snooze or not to snooze.

The point is if you have the time to snooze for an hour, would you not get better sleep by just setting your alarm an hour later?
No. I can naturally wake up after 6 or so hours of sleep on weekends when I go to sleep at 4am, but the entire work week I have to ease myself up with a few hits of the snooze button, even after 7-8 hours.

(My snooze is also set to 5 minutes, not an hour)

Same. There is a tight correlation between my sleep habits and happiness for me. When I’m being a night owl I am typically staying up late videogaming, but I’m rarely happy. Early rising me is both productive & happy.
If you’re not experiencing any symptoms of sleep deprivation, then you’ve probably just got a normal circadian rhythm.

You might be a ‘night owl by preference’ and had some bad habits, but there are plenty of people who are night owls by necessity because of their circadian rhythm.

In my experience and the research I've read, you've almost mentioned all the top relevant reasons: alcohol use, stress, and reduction in sleep (kid being born). It's unlikely to be age.

I'd highly recommend last year's "Why We Sleep" [1] for more info on memory performance and how it's impacted far more that you'd suspect by full (and quality) sleep, which is in turn impacted far more than you'd suspect by alcohol and stress (not to mention kids).


"Why We Sleep", by Matthew Walker [1]. I've read a lot about sleep over the years, but I still found it fascinating and comprehensive.

I've mentioned the book on several other thread [2], so there's plenty of opinions there if you're interested in knowing more.



Every single person here, if your serious about diving into the science of sleep, should read Matthew Walker's book: Why We Sleep:

His interview on Joe Rogan is a good summary:

He covers everything from why we sleep (obv), naps, melatonin, etc. I've just finished it and really enjoyed it.

Kevin Rose also did a podcast with Matthew Walker shortly after the book came out
I think lots of people reading hn have picked it up in recent weeks, I just finished the first two chapters myself :)
+1 was recommended to me a couple of weeks ago on HN. Most useful book I’ve read this year, easy.
I am reading this right now as a chronically sleep deprived person and it is terrifying - no less than 7 hours for me from now on.
According to the author, with 7 hours of quality sleep, you are still sleep deprived; after 24 days, you would be sleep deprived in amount equivalent to someone not sleeping 1 full night.
Most of the "oh crap this is really bad" examples provided so far (I'm not done with the book) seem to have been for 6 hours or less, I figured 7 hours is a reasonable absolute minimum. I will aim for eight. However at this rate I'm afraid the more paranoid I get about not getting enough sleep the more difficult it becomes for me to fall asleep. I've never had issues sleeping, but this book coupled with having just moved to an apartment with a train nearby that's taking some getting used to is making me lie in bed and think about needing to sleep for longer before actually drifting off to sleep.
Seconding this. His data on agents of sleep disruption/degradation of sleep quality were eye-opening.
Thanks. Saw this book being recommended multiple times here so just bought it :)
Joe Rogan is one of the biggest propagators of pseudoscience. It's not a good sign when a guest appears on his show. Joe usually tries to rope them into talking about his two favorite health topics: cholesterol and testosterone.
Eh, I've listened to hundreds of his episodes. Some are good for a laugh, some have interesting guests and I learn a thing or two, some I can't make it through. Not everything has to be a text book. What exactly is the problem? I find the unedited, uncensored, long form, 1 on 1, conversational style very appealing - Joe is just a chatter box to keep the guest talking.
I presented the problem clearly.
You must not listen to him recently. I've listened to maybe 15 episodes and haven't heard either of those yet. He's been a pretty level headed host. It could be that he's better than he used to be because I've only listened to recent episodes, but it's been great so far.
I haven't listened to a lot of Joe Rogan but from what I have listened (maybe last 6-7 episodes) and wearing my Dr hat I feel he fluctuates. He seems to walk a pretty level line but then occasionally drops things that are demonstrably false. More out of ignorance than malice I believe
Hi atomical, that's an interesting claim. Can you explain more why you believe that? I have listened through a couple of episodes and those made for interesting discussions.

edit: I get that he makes fun of him in later episodes, but that's only gonna pop up if you're watching youtube. for people listening on a podcast app, or with adblocking, or whatever else, they don't see the disclaimers. he's not a journalist and is rarely informed enough to challenge his guests, which totally counteracts his "open-minded" reason for having alt-right, pseudo-scienctific, snake oil salesmen, and bigoted people on his show. he's a dunce for giving his platform over to such obvious hucksters so often, which is only bolstered every time eddie bravo comes on (an idiot if there ever was one).

He needs to brush up on The Placebo Effect.

(The Placebo Effecy is so important; I don't know why it isn't taught in grade school.)

I completely disagree, at the very least it is not intentional. He's interested in a lot of topics and explores a wide range of topics, he's not going to get everything right. What I will say is that he brings on a ton of interesting guests and they should not be judged because they participate in Joe's podcast.

> It's not a good sign when a guest appears on his show

Why does this matter? I find this line of reasoning corrosive and hypo-critical. Each guest should be judged on the basis of their merits, character, not who they choose to have a conversation with.

That is an excellent book. However, it doesn't contain a lot of practical advice (other than the 12 points at the end of the book, which were released already by National Sleep Association)

Somewhat tangetial, check out "The Circadian Code" as well - a lot of more practical advice in this one. They actually disagree on couple of delicate points, so not sure how can one make up one's mind as to which one's correct (e.g. one thinks there are night owls , one thinks it's a myth; one thinks we need 7 hours of sleep, one thinks that less than 8+ hours of sleep is devastating).

But in general, the message is the same - sleep well, try to fit into your circadian rhythm because all organs have internal clocks and being in rhythm benefits them all; some of them are interconnected, some are dependent on SCN, etc

In particular, the clinical trials with TRE (Time-Restricted eating, as in putting all calories in 8-12 hour intervals daily) seem amazing. Not a single side-effect, and all health markers seem to be improving under it.

One important study on mice concluded that mice that ate their high-fat, high-sugar food in 8 hour intervals (lets say, 8AM -> 4PM) compared to the control group of regular mice that had high-fat, high-sugar food all the time, ate more or less the same amount of calories daily, but the TRE-group had no increase of blood sugar or body fat.

Seems too good to be true, but apparently the study has been replicated..

Does anyone have links to solid studies that provide some better answers if there is a significant share of people who can live on little sleep? As they tell you that you won’t recognize yourself if you’ve slept enough, I don’t quite trust my instincts
Mice have very fast metabolism. Converting mouse models to humans requires adjustment.

There is some evidence that for humans eating all calories within 4 hour window might have similar effects.

I don’t really think it works in the same way for humans. I have been doing it for decades and I can assure you that my body fat increases if I overeat.
End of the day you still have to burn more calories than you take in and also eat less carbs and sugars. I think once you do that any benefits are marginal(based on my personal experience)
Have you been doing TRE in 8 hour intervals? There was a study on this as well, and it turns out a lot of people simply think they are doing TRE, but once they start writing down exactly what they eat and exactly when, turns out it's far away from TRE.

I've always believed in the law of thermodynamics myself - counting just the calories, but I keep an open mind for now until someone can refute it. The blood sugar thing makes sense to me with what I know about melatonin suppressing the insulin - that's a fact. But the rest of the conclusion.. who knows.

>I've always believed in the law of thermodynamics myself - counting just the calories

Counting just the calories ignores second order effect, and diet is all about second order effects.

If one could absolutely stick to counting the calories and eating the specified amount, of course one would lose weight.

But e.g. a diet of only having 1500 calories of broccoli for 1 year, and one would be ill from lack of tons of nutrients and vitamins (and they'd have stopped much earlier anyway).

E.g. if one eats certain kinds of foods, your appetite increases and it's more likely to overeat. Not giving one's self some foods they like, also makes it easier and more tempting to break a diet. And lots of other factors (exercise, hydration, nutrition, and so on) unrelated with counting calories, that still affect what we eat and how we process it.

One / your / it / we: make up your mind on pronoun and stick with it!
Maybe focus on the content?

Any disparity is just on this single sentence: "your appetite increases" (as opposed to "their" or "one's").

"Their" as used across the comment is not meant as the plural possessive. It's instead used as a gender-neutral pronoun (a common use) to avoid repeating "one's" or using "his/hers".

It, in "your appetite increases and it's more likely to overeat" etc., refers to the situation/possibility (as in "If they sky's cloudy it's more likely to rain"). It is normal to use different pronouns to refer to different entities.

Finally, the "we" at the end is perfectly fitting. It's a generalization, beyond what each individual does.

It was really distracting to read. The mix - and there was a they in there too - broke focus. Sorry.
No problem!

Though "they" was used as a gender neutral pronoun -- not to change the subject from "one" to some group. E.g. as in: "if one drinks milk, their bones would benefit".

I think once you've chosen "one", you need to stick with it: "if one drinks milk, one's bones would benefit".
I think I'm a night Owl with DSPS. For the past few weeks I have been trying to shift my schedule to wake at 4:30AM, go running, eat within 6 hours (Time Restricted Eating), and repeat - but my body is rejecting this like an allergy - I just feel awful.

I felt best running in the evening a little before sunset, getting back and eating within 6 hours, and going to bed around 2-3AM.

I had to change my schedule because we have bad Ozone problems in Phoenix AZ, so O3 around sunset was terribad — not worth running (if it was for health, anyhow).

Which book do you recommend? I feel like I'm fighting my body; since I began "waking" at 4AM (I think I'm already kinda awake) I can't sleep for more than 1-2 hours and get tired around 2PM. If I fall asleep at 2PM then I REALLY sleep, for many hours, and wake around 8PM.

Its a total mess.

I'm doing everything I know how: be in the sun early, melatonin, activity early, calories early, TRE, avoid blue light before bed, but my body still seems to reject the early bird protocol.

I recommend you to read "Why We Sleep", however try not to be discouraged when you think about your sleeping pattern and what the science says it damages, and how it is devastating, detrimental to your health and so on. It can be overwhelming a little. If I had to choose one, this is the book I'd recommend.

I've only got my experience with sleep deprivation and the methods I use to fix it. I had severe sleep deprivation and now I sleep 8 hours on average, with quality sleep.

I am a very light sleeper, on top of having problems falling asleep. This is what I did:

1) limiting the noise - I installed new windows and added new door that leads to my bedroom; I have a fan that I put next to me, put it on the highest speed and it absorbs any noise left. You can achieve this with a "white noise app", too.

2) completely dark room - I cover the windows outside, and then inside too (just in case any light escapes).

3) I fit my meals within 8 or 9 window as a part of TRE (Time-Restricted Eating) - my first meal is around 9AM. It does not have to be perfectly accurate (8:45, 9:15 acceptable)

4) strength training every day (assuming you are cardiovascularly fit); I do sprints as well (twice a week or so)

5) zero alcohol - it is one of the strongest REM suppressors

6) zero caffeine - very important. The average half-life of caffeine is 6 hours. That means that after 6 hours, you still have 50% caffeine in your body.

7) write down the following, and try to look at them from time to time: when you eat, what you eat, calories/macros breakdown, when you go to bed, when you fall asleep (approximately), when you wake-up, and a summary of the previous afternoon and night time - what you think is the reason for the sleep (or lack of) on the day of

8) try to fit in with your circadian rhythm. On average: we are at our peak 10AM-3PM - try to fit strenuous activities in this period (including heavy strength training - since I am a remote developer, I can do this).

9) I walk around 8-10 km every day, part of it in the morning, part of it around 20:00

10) try to limit blue light at night - some ideas: dim lights, orange/red glasses filter, orange/red light bulbs.

----- These were the major things that I did, and some combination of them seem to work. I don't know which ones precisely. Some things that didn't work for me:

1) some natural remedies like valerian tea, etc. - it made me worse, actually. 2) meditation - just doesn't work (for me). A lot of people swear by it.. 3) nothing of this sort:

Try to learn something from what you eat - but be brutally honest with yourself and write down everything that contains calories that you eat. I noticed that I sleep worse on the day I eat more sugars (and I hardly eat sugar at all!).

Hope this helps someone.. I know how hard it is without sleep.

It does get better with age in that your circadian rhythm will shift as you get older. It's a crime that we force adolescents to wake up far earlier than they are biologically wired to just so their parents can get to their jobs. According to Matthew Walker (Berkeley professor and sleep researcher), waking up at 7 is equivalent to an adult waking up at 5. Highly recommend his book on sleep. It's incredible, the best non-fiction I've read in the last couple years.
Indeed, this book is well worth anyone's read. Many insights on sleep and productivity (the effect of alcohol on sleep quality was particularly shocking).
I would recommend reading Why We Sleep by Matthew Walker instead. [0]

The Promise of Sleep is an okay book, but it is almost 20 years old now and it shows.

I have read both books and it is remarkable how much more we learned in the time between them.


This was also discussed in a good book about sleep I read a few weeks ago: Why we sleep
And if you want to learn more about why its important to sleep, you should read the book "why we sleep" which is where I found this list.
I am more than half way through the book "Why we sleep?" by Matthew Walker and it is not a surprise to me that misalignment of circadian rhythm with class schedules results in poor grades. The book goes into great detail on the importance of getting eight hours of sleep on a regular schedule. Getting less than eight hours of sleep is tied to every imaginable disease and poor memory. I highly recommend reading the book.

Does it offer any solution?
~8.5 hours.

Most of my life I did the typical not getting enough sleep and then binging on the weekend, which doesn't work well at all. Since reading "Why We Sleep"[0] though, I've changed my lifestyle to prioritize getting quality sleep every single night. That book was pretty eye-opening in obliterating a lot of myths I believed about sleep and then teaching my how complex and important it is, indeed it is just as important as waking time if not more. The idea that time spent asleep is "wasted time" is now absurd to me, as so many bad things happen when you short sleep.

Since getting quality sleep regularly it's been like unlocking a superpower: retaining more information, better progress with strength training and skill-based hobbies, more solid emotional balance and way more motivation / inspiration at work.

Can't recommend that book enough.


Jan 04, 2018 · krausejj on Why Do We Need to Sleep? is a fantastic new book on the subject, if you're interested in going deeper
Interesting. Have you found a difference in your sleep patterns since getting the treatment? One anecdote I've heard is that people on the spectrum have difficulty entering REM sleep[1]. Since REM sleep is partially initiated by eye movement, it makes sense that forehead and sinus shape could impact it.


I can highly recommend the book - Why We Sleep - mentioned at the top of the video. It goes into quite some depth on the reasons for and mechanics of sleep in a way I found approachable for someone with only a layman's understanding of chemistry:

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