"Why We Sleep" by Matthew Walker summarizes quite a lot of research on sleep. It leaves little doubt - we currently know of no safe way to significantly cut down sleep.
I haven't seen the research presented in that book being refuted.
I think this book is mostly bullshit - the same author that wrote the linked HN post dug into that book and there was a ton of manipulative data and just straight up false claims. [0]
> “Sleep is not like the bank. So you can't accumulate debt and then try and pay it off at a later point in time. And the reason is this - we know that if I were to deprive you of sleep for an entire night - take away eight hours - and then in the subsequent nights, I give you all of the sleep that you want - however much you wish to consume - you never get back all that you lost. You will sleep longer, but you will never achieve that full eight-hour repayment as it were. So the brain has no capacity to get back that lost sleep...”
I don’t think this follows - seems likely to me that sleep is not some linear time thing and that there’s a standard overhead that doesn’t need to be repeated to extend and make up the time. This feels like a symptom of not understanding the mechanism and making a bad assumption.
I also found the “I won’t mention the cognitive failures I can detect” irritating. If there’s some actual thing to mention, say it - this kind of thing sets off alarms for me.
It doesn’t surprise me that the rest is similarly bad.
By 'vibe' I mean a ton of statements that sound likely to be false or at least would surprise me if they were true that aren't backed up when you look closer. The fact that the information is surprising isn't bad itself, but it spikes curiosity - then when I look deeper there isn't much actually there to support the surprising claims and what is there has a ton of issues.
There's a lot of 'wow, isn't that interesting' talk and deference to authority on an 'important' issue, but little talk of the actual mechanisms of how things work, little consideration of obvious counter examples that could be an explanation (like the one in my comment).
The sense is that the argument is driven by motivated reasoning instead of trying to understand what's true. Basically starting with a position and forcing the data to fit your pre-existing position.
It feels like I'm being conned by someone making up bullshit for status or some other agenda (maybe just sunk costs into an existing theory). Often bullshit and complex interesting topics can sound similar at first and it's helpful to have some sense for telling the difference. Otherwise you wander around impressed by 'energy crystals' and worried about 5g.
Walker has clearly made a huge name for himself and sold a significant number of books by skewing the evidence to make his thesis sound more substantial than it is
It's less about the specific content, and more about continuing to push something without good science behind it.
For example: I think X is true, I cherry pick data to back up X and publish a book on it. This book gets a lot of attention and is good for my career, but it's based on bad science and misleads people. This is a theory I identify myself with along with my success and my own career, if its ideas are invalidated that reflects negatively on me and my abilities (and potentially the ability to support myself). There's an incentive to rationalize or continue pushing the bad science which slows down figuring out what's really true. This has happened a ton of times throughout history.
In this specific situation the benign case is people sleep more and it doesn't matter (or it helps), in the pathological case people are anxious about their lack of sleep and it negatively effects their life or they sleep more than they personally need and it turns out over-sleeping is co-morbid with depression and causes other issues.
In the general case popularizing bad science has knock on effects that make it harder for people to get funding to study ideas the contradict the popular, but incorrect zeitgeist of what's commonly thought to be 'true'. It can also lead people down rabbit holes that can take a long time to crawl out of and make it take longer for people to understand what is actually true.
You can't just hand wave this away by saying "I know X is true, therefore it doesn't matter if the data is a little problematic. X is true and it's good for people to know that". A lot of times X turns out not to be true, not to be entirely true, etc.
I don't know if you can call it an agenda but I think there's something like a 'wellness' or moderation bias in these fields. The idea that you need to balance out hard work, slow down, and so on.
For example, as it turns out there is little evidence that stretching actually does anything, yet a lot of experts used to recommend it for decades. Same with nutrition, 'balanced diets', workouts at low heart rates and so on.
What do you mean that stretching doesn't do anything? Any links to such evidence? It's a pretty simple experiment to stretch every day for a month and measure your flexibility gains, so that's quite a bold claim. Do you mean it has no direct impact on your health?
it actually has negative impact on health and injury in people who do static stretches in particular is significantly increased. (as is in people with high levels of flexibility in general)
Nowadays stretches as a warmup are not recommended any more.
I get the “vibe” because of the misuse. I regret using the colloquialism since people seem to have such a strong reaction to it. I just meant my skepticism went up from what I was hearing.
First, if you "can't get back lost sleep", wouldn't that mean that you were tired forever? I'm definitely more tired after 24 hours awake than 18. But I can sleep and get back to normal.
Second, I once stayed up for almost 3 days straight. At the end of that, I slept for 24 hours straight. I woke up the next evening as if it were a normal morning, fully refreshed. (I went to bed about 5pm, and woke up about 5pm the next day.)
If I didn't "bank" my tiredness and pay it back with sleep, how is that even possible?
Sleep is essential for memory and skill consolidation. What they mean by not being able to recover sleep is that if you (for example) try to learn something while sleep deprived, more of those memories will be lost the next day. Sleeping extra on the weekend will not make those memories come back. The benefits of sleep are "lost" forever.
now, it's obvious to me that if I don't get 8 hours of sleep a night, my brain stops functioning properly and my entire life goes to shit very quickly. So I was happy to see a very popular book advocating sleeping well, and hopeful that if lots of people read it, they might have more respect for other people's sleep schedules.
The critic, Alexey Guzey, seems to be a guy who needs less sleep than I do, and also a guy who is into life-hacking/self-improvement type stuff. There's definitely a type of person who thinks "sleep is for the weak". I think he probably does have a bias towards sleeping less.
But I think the problems he points out about the book are pretty serious.
In particular, it seems that claims around sleep and longevity and other health outcomes (e.g. injury rates, cancer) are often unreliable or based on misinterpreted studies, and one case involves eliding data that contradicts the result.
Now, having myself experienced chronic sleep deprivation, and dealt with people who think they don't need to sleep but definitely do, I think the basic argument of the book is probably correct. But as the last line of that post quotes, "Good ideas do not need a lot of lies told about them to gain public acceptance".
I wouldn't say this is refuting even a minority of claims in the book. It appears to be a thorough fact check of a small percentage of claims, some of which is going after the author over wording and inconsistencies. It's fair criticism, but by no means invalidates a majority of the information regarding sleep that Walker presents
After finding that the part of the book which actually got fact-checked is full of falsehoods and contains outright falsifications, your conclusion is "well, the rest of it must be fine"?
Except there are cases where Walker went so far as to remove portions of a graph to support his argument. This kind of manipulation shouldn't be allowed to stand and it's frustrating (though not surprising) to see a book that relies on this sort of dishonesty get so much uncritical attention and praise. I can't put it any better than Andrew Gelman:
"If the data didn’t matter, then why did you include them in your damn book in the first place? If the removal of the bar from the graph didn’t matter, then why did you remove the damn bar?"
Okay, he removed the 5 hour bar. I get what the author in your link is upset about, leaving out data points. But imo that's not good enough to make me throw out all the information in that book.
It sounds like the author is upset a book about getting enough sleep is getting so much attention. If they're upset at the way Walker misrepresents information, then I'd hate to see the author's blood pressure while feverishly researching the bias of every article they come across
I'm genuinely surprised someone could read that whole blog post (I'm assuming here) and come away with that conclusion. Gelman addresses this so directly in the article:
"Recall the Javert paradox. It’s completely reasonable to write about scientific misconduct, and yes sometimes we have to scream a bit to get heard over all the chatter of the scientist-as-hero press."
...
"But we need real expertise, not fake expertise. I’ve said it before and I’ll say it again: Gresham, baby, Gresham. If we don’t contest the fake expertise, I’m seriously worried it will be crowding out the real stuff."
There is good research and there is bad research. The latter should not be given a pass just because all research has some amount of bias.
This 100%. I've read the book twice, coming back to certain chapters more than twice, because it's dense with information. It's scary really. The single most impactful thing you can do as a human for your life is to prioritize 8 hours of sleep per night, full stop.
I haven't seen the research presented in that book being refuted.