Book review: Why we sleep

post by ricraz · 2018-09-19T22:36:19.608Z · score: 49 (22 votes) · LW · GW · 11 comments

This is a link post for

I read this book (by a sleep scientist called Matthew Walker) because I knew that it would tell me to sleep more, and I hoped it would cite enough scary statistics that I'd be likely to actually follow through. Well, it worked - I'm keeping a copy on my bedside table for the foreseeable future, just as a reminder. In addition to the exhortations to get more sleep, it contains a variety of other interesting and important facts about sleep.

What is sleep?

What's it good for?

The evolution of sleep

How to sleep better

As you can probably tell from the above, Walker is very much a cheerleader for sleep. This does bias him in some noticeable ways - e.g. his overt scorn towards coffee. He also blurs causation and correlation at some points throughout the book, so I'd be surprised if all of the deleterious effects mentioned above are as significant as he claims. But the overall picture is stark enough that I'm now very worried about the ongoing sleep loss epidemic.


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comment by habryka (habryka4) · 2018-09-19T23:18:48.949Z · score: 26 (9 votes) · LW · GW

I think I would love to see an epistemic spot-check in the style of AcesoUnderGlass for this book. If anyone is up for it, I am happy to put out a $50 bounty for anyone writing up such a post and post it to LessWrong.(Independent of quality, as long as it's not completely egregious. If more than one person ends up writing one, then I am happy to pay out the price up to three times)

comment by yagudin · 2018-09-24T11:00:06.549Z · score: 11 (2 votes) · LW · GW

The most in-depth, but a bit outdated (c. 2012) article on sleep is written by Piotr Wozniak, whom you might know as a pioneer of spaced repetition software. The article is ~300 pages long. It includes summary & myths sections which are a bit longer than this post.

comment by jmh · 2018-09-24T16:43:55.064Z · score: 3 (2 votes) · LW · GW

Just a side question here about the "a bit outdated (c. 2012)" note. Is that because you think the science/level of knowledge or some other technology related to such studies is changing that quickly?

Both the reference to additional sources and the review were great. Thanks to both you and ricraz.

comment by yagudin · 2018-09-28T15:08:21.429Z · score: 1 (1 votes) · LW · GW

You are welcome! A general concern about the pace of scientific progress.

comment by yagudin · 2018-11-02T22:39:23.984Z · score: 1 (1 votes) · LW · GW

Wikipedia page for 'Cognitive behavioral therapy for insomnia' is a great source of useful sleep related habits.

comment by Elo · 2018-09-19T23:49:54.566Z · score: 5 (2 votes) · LW · GW

Good book. Would recommend.

My major take away is that sleep problems are usually psychological not Physiological. Usually people don't know how to stop a busy mind and sleep. This leads to endless rumination and being held awake by stress. We don't teach the skill and most people just figure it out on their own.

Also extra sleep tips here:

comment by Sherrinford · 2018-09-20T09:56:24.939Z · score: 4 (2 votes) · LW · GW

Thanks for the interesting review summary. Does he say a bit more about the effects of napping / biphasic sleep vs monophasic sleep?

comment by ricraz · 2018-09-20T18:26:31.397Z · score: 1 (1 votes) · LW · GW

I'll check when I have a copy at hand. From memory, he says that the "biphasic" sleep where you wake up in the middle of the night for an hour or so has no scientific backing. I think his main evidence for the health benefits of of afternoon naps is looking at the rates of heart disesase in Mediterranean countries as their sleep patterns shift. This doesn't seem to be particularly rigorous, but I recall the effect size being pretty large.

comment by habryka (habryka4) · 2018-09-19T23:27:35.540Z · score: 4 (2 votes) · LW · GW

Great post! I generally find book reviews and book summaries quite useful, and am happy to see more of them. On the object level, I am vaguely remembering a study that I can't find right now, that added something interesting to the sleep question, which was something like this:

"We had three test-groups, one of which slept normally at about 8 hours a night, one of which slept for 7 hours a night, and one of which slept for 6 hours a night, for a week. The 7 hour group started out with a similar performance to the 8 hour group, but went down to the performance of the 6 hour group after about 4 days. However, the self-assessment of how sleep-deprived the individuals were was quite accurate for the 6 hour group, but didn't identify any worsening aspects of sleep deprivation for the 7 hour group, even after 4 days of testing. This suggests that subjects are quite bad a assessing mild sleep-deprivation, even after prolonged exposure."

I wonder whether the book made any reference to that study, since I've been looking for a while, and if anyone can find it, than I do remember it being a significant update on how much I trust myself to assess how much sleep I need.

comment by MakoYass · 2018-09-22T23:57:24.211Z · score: 3 (1 votes) · LW · GW
Humans seem to be naturally biphasic: modern hunter-gatherer tribes sleep for 7-8 hours at night, and then nap for 30-60 minutes in the afternoon.

I'm having fun imagining a workplace where this sort of pattern is encouraged. A large part of the difficulty would be dealing with self-destructive work cultures where nobody wants to violate a norm in a way that risks making them look lazy. I'd want to start by having the highest performers try napping after lunch, so that people come to associate it positively with productivity, frame napping as the opposite of lazy, like exercise, it's not work but it's something that hard workers do. But there's a chance the higher-performers are exactly the people who wouldn't benefit from napping- There is such a thing as a short-sleeping gene in humans and a lot of CEOs seem to have it- so starting with them might soil the whole thing.

I'm remembering hearing stories of a lot of workplaces getting nap pods and telling their employees that it is "okay" to nap. I don't think this should be taken seriously. If you don't have enough beds for everyone in the office to sleep, it wont become a norm. It certainly wont become a habit.

I'd want to experiment with assigning a sample of people (or a set of volunteers) to napping every day, that's a design we could take seriously.

comment by SquaredCircle · 2018-09-20T15:51:11.077Z · score: 1 (1 votes) · LW · GW

Thank you for the write up! Matthew Walker was also on The JRE Podcast and has a Talk at Google. Well worth checking out.