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[–]Direwolf202 26 points27 points  (3 children)

I think the author is exaggerating it a little - and certainly, the errors that I did notice got rarer as the book continued - the first chapter was the worst.

That said, it is a book that I feel needed a few more drafts and a more careful approach - these errors are egregious for a book purporting to be scientifically informed - considering how they do go against replicated and well known research.

[–]guzeysci acc[S] 16 points17 points  (2 children)

[–]Direwolf202 11 points12 points  (1 child)

I have. I don't disagree. But as I said, the book is, on the whole, better than what you show there.

I understand why you structured your critique as you did - I simply feel that it isn't an entirely fair representation of the book.

[–]guzeysci acc[S] 3 points4 points  (0 children)

Hmmm - I can't rigorously back it up because I haven't looked into the rest of the book very deeply, but from my impression reading it, the rest is just as full of misrepresentations and exaggeration - the bit from Chapter 8 that I posted being the prime example.

[–]smidivak 43 points44 points  (33 children)

Having previously read the book, and pretty much taken it as gospel, I am now back to being a slightly more informed ignoramus when it comes to sleep. Here is hoping that someone will make a synthesis of the two views and I can read that and again feel very informed.

[–]Kinkajoe 68 points69 points  (29 children)

I study sleep. While some of walker's claims may be hyperbolic, I think they are within reason and justified by the important message he is trying to convey. Too many people have begun to forego sleep in their health choices, and he has helped raise awareness of sleep's role in our health.

Many of these criticisms are quite unfair or misunderstanding the science.

Claim 1: The author finds some papers that demonstrate a U-shaped relationship between sleep duration and all cause mortality. It's relatively well accepted that the right side of that U is attributable to the increased sleep duration of individuals with some sort of underlying comorbidity. The Cappucio paper they cite states "sleeping 9 h or more per night may represent a useful diagnostic tool for detecting subclinical or undiagnosed co-morbidity." It is well documented that people who are ill sleep more. Most healthy, non-drug using individuals will have trouble truly sleeping more than 9 hours every night. Additionally, all of these papers, except the one the author used for the graph, find that between 7 (sometimes 6) and 8 hours of sleep is optimal. (The majority also classify 8.4 hours of sleep as 8, due to integer coding). Walker suggesting people aim for 8 hours, when accounting for time to sleep and the poor planning abilities of most people, allows people to sit in that 7 and 8 hour range. The point is not that 'more sleep = more life'. Its that below 6-7 hours, negative outcomes rapidly increase. None of these papers look at end-of-life subjects either, where I believe most of the negative consequences of a lifetime of short sleep occur, especially in a neurodegenerative context.

This is especially important because of something the author states themselves; that subjective sleep times are notoriously unreliable. This is true. In fact, it is well documented that people very consistently underestimate the amount of sleep they get. This well-cited paper finds that people tend to over-report the amount of sleep they get by almost an hour. Recommending 8 hours of sleep is a good way to ensure people get that 7-8 range.

Further, all cause mortality is a poor measure of health outcomes, due to the “correlation causation” the author mentions. Objective and molecular metrics of sleep restriction, which obviously cannot be done longitudinally, have found strong negative molecular side effects from single or repeated periods of sleep deprivation. While all-cause mortality data is fuzzy, specific diseases such as CVD Alzheimer’s display a more consistent picture. As far as I can tell, the author bases their hypothesis off of just one paper showing a slightly lower all-cause mortality in a 6-7 hour cohort than 7-8 hours. The entire body of human evidence shows as a whole that anywhere in that 7-9 range is reasonably healthy, depending on the person. This is reflected in expert opinion and NSF recommendations. The claim that “Walker’s book has likely wasted thousands of hours of life and worsened the health of people who read it and took its recommendations at face value” is absurd. No one’s health will be worsened by sleeping 8 hours a day.

Claim 2: The last paragraph above also explains that while sleep deprivation does help treat depression, longer term use does not work. The negative side effects build up. If someone wants to sleep less for a night to help their mood, go for it. I think Walker is just emphasizing that it is not a safe long term treatment. There’s also emerging evidence this SD therapy works by helping realign the circadian rhythm. This and some previous evidence demonstrate that the effects of SD therapy could be achieved by keeping a proper and consistent sleep schedule. So sleep deprivation may help with depression, but indirectly by modulating another variable.

Claim 3: Sleep will kill you if you don’t get any. Of course Walker uses FFI as an example in humans because we’ve never done scientific studies to the point of death. Someone can’t kill themselves with lack of sleep because your body forces you into NREM before that point. But we know from animal studies that mammals eventually die without sleep.

Claim 4 and 5: I do not know about the WHO’s policies, but sleep loss is an important issue and prominent in developed societies. Whether or not you call it an epidemic is a matter of semantics to me as a scientist, but some of the other comments have made a good stab at refuting this. The study the author links showing people don’t sleep as little as Walker claims is a self-reported phone app study. Phone sleep recording apps are notoriously bad- they count time in bed, not sleep time- and by limiting data to individuals who choose to send their data you’re heavily biasing the data. I don’t think anyone knows the exact numbers, but the CDC finds at least 30% of workers sleep less than 6 hours, and whatever the number is sleeping 6-7 hours, I think its fair to say this is a severe public health issue. And its increasing in prevalence. Why is the author taking such offense at the difference between recommending 8 hours and 7-9 hours? Functionally, theyre quite similar, and 8 hours as a public health policy is far easier to market. Additionally, recommending 7 could lead to chronic undersleeping as illustrated by humans’ tendency to overestimate self-reported sleep duration.

The author has a large appendix of ‘scientific falsities’ in the book, which I found strange. This is a book intended for the public, of course its not going to be written in a manner consistent with scientific discourse. Much of these criticisms in this section take issue with semantics. For example, they state in Appendix 19 that Walker’s claim that every ‘creature’ has a circadian rhythm is false. Creature, in colloquial use, means animals, not single cellular organisms. Would the book have been enhanced for the every reader by including the taxonomical limit where circadian rhythms disappear? (Also, yeast do appear to exhibit ultradian rhythms, which is pretty close to a circadian on, just on a different timescale.

There is genetic variation in how much people need to sleep, but based off my research I’d say 7-9 hours covers a few standard deviations from the mean. What I recommend for people usually is to try and find a sleep timing and duration in which the individual wakes up naturally multiple consecutive days in a row. Shoot for that amount. Again, overall, the author is trying to refute small inconsistencies in certain numbers and claims from Walker, but the book is just trying to get the word out that aiming for 8 hours of sleep is a good goal for everyone. The author’s biggest argument- that people should sleep 6 instead of 8 hours, is based off one all-cause mortality study.

Apologies if this is not coherent or comprehensive enough. It’s a weekend here and I couldn't tackle every point or include every paper. If anyone has any questions shoot a comment or message.

[–]YeezyMode 15 points16 points  (8 children)

Seconded except I don't study sleep. There has to be a word for the last statement you made, I've come across it numerous times and it's always some pedantic takedown of hyperbole or exaggeration without looking beyond the surface/literal meaning of something.

[–]ScottAlexander 46 points47 points  (3 children)

[EDITED: This was in response to a previous version of this comments thread, before kinkajoe edited in his argument]

I've previously criticized some of guzey's takedowns for being overly critical and pedantic, but I found the concerns raised in this one pretty concerning.

While I agree that overall probably sleep will be found to be good, I think it's important to avoid a kind of arguments as soldiers situation where we don't care if somebody's using bad data / stretching the facts because they're pushing the "right" side.

If Walker wrote a book saying "everyone knows sleep is good for you, but there's limited data in support", nobody would object. Walker was trying to do something more ambitious, to say "data proves sleep is even more important than you thought!", and if that's not really support-able I think that's a reasonable critique of the book.

[–]YeezyMode 2 points3 points  (2 children)

Got it. I would always want to avoid that situation as well as it could cascade into complete misinformation.

My original interpretation as a reader of the book was "Sleep is important. This book supposedly has data showing how and why." I came out of the book with the same impression and hadn't really attached any extra importance to sleep due to pure data. I still don't think the critique should lead one to start questioning the importance of good sleep. Using the part about depression as an example, there is a huge amount of literature devoted to sleep deprivation being linked to mental illness strongly, especially depression. In OP's post there is a distinction between acute and chronic. But even taking that into account, among the so called papers proving sleep deprivation's effectiveness as a therapy, many of them combine the therapy with drugs, many show no marked improvement, and many clearly state that the whole reason the sleep deprivation was useful to begin with was because it acted as a reset to the subject's natural circadian rhythm.

I guess from the perspective of 'changing minds', I'd hope for someone to read the book and this critique, and come out with the idea presented in the first sentence of guzey's conclusion. But if someone were to already be in a mindset described in Kinkajoe's post, this article could easily be the thing that pushes them into abandoning any improvement related to sleep quality.

[–]guzeysci acc[S] 7 points8 points  (1 child)

I still don't think the critique should lead one to start questioning the importance of good sleep.

I don't see how my critique would lead one to start questioning the importance of good sleep. In the conclusion I write:

If you take one thing away from this entire essay, remember this: as long as you feel good, sleeping anywhere between 5 and 8 hours a night seems basically fine for your health

Could you point to any passages in the essay that seem like they could lead to that kind of questioning?

[–]YeezyMode 6 points7 points  (0 children)

Please read my comment more carefully. I mention that it would be positive if a reader did come out with the conclusion that you present, but there is a risk of something else if they're predisposed to a mindset of justifying a poor lifestyle.

[–]guzeysci acc[S] 7 points8 points  (3 children)

Could you point me to any hyperboles or exaggerations in my essay?

[–]YeezyMode 15 points16 points  (0 children)

I was referring to takedowns of hyperbole. In this case your article nitpicking exaggerated claims from the book. I'm not interested in carefully presenting a rebuttal of specific points from your piece but as with the section you wrote on potential harm, I feel the potential benefits of loosely following the advice of Walker's book far outweighs other factors. Whereas I believe your article could geniunely harm those who use the thought process described in the original comment I replied to.

[–]guzeysci acc[S] 7 points8 points  (7 children)

I'm not going to respond to this whole thing but this comment doesn't appear to be too credible. I'm going to respond to their first argument, their last argument, and to comment on their general reading of my essay.

1.

They say I'm misunderstanding science but they selectively cite scientific evidence I presented in their very first claim. They write:

Claim 1: The author finds some papers that demonstrate a U-shaped relationship between sleep duration and all cause mortality. It's relatively well accepted that the right side of that U is attributable to the increased sleep duration of individuals with some sort of underlying comorbidity.

  1. first of all, this does not mention Walker. I was responding to Walker who claimed that more sleep means longer life span. The author of this comment seemingly doesn't care about the context of the discussion
  2. No, this is not "relatively well-accepted". The commenter cites Cappuccio, but they write "MAY represent" - this is a hypothetical statement that they make. Further, the commenter avoid citing the paper by Shen et al I cite right before Cappuccio in the essay. That paper reads:

Proposed mechanisms for mortality associated with long sleep include33: (I) long sleep is linked to increased sleep fragmentation that is associated with a number of negative health outcomes; (II) long sleep is associated with feelings of fatigue and lethargy that may decrease resistance to stress and disease; (III) changes in cytokine levels associated with long sleep increase mortality risk; (IV) long sleepers experience a shorter photoperiod that could increase the risk of death in mammalian species; (V) a lack of physiological challenge with long sleep decrease longevity; (VI) underlying disease processes mediate the relationship between long sleep and mortality.

  1. The author of the comment fails to mention that short-sleep is definitely in some cases caused by disease. As an example, many stroke patients suffer from insomnia https://www.nature.com/articles/s41598-018-26630-y - this means that the left tail of the U-graph also has some sort of "underlying comorbidity"

Thus, in the first argument, the commenter appears to have misunderstood both my argument and the scientific literature. Further, it appears that the commenter didn't read my essay carefully to notice such things as this:

2.

In their last sentence, the commenter writes:

The author’s biggest argument- that people should sleep 6 instead of 8 hours, is based off one all-cause mortality study.

I never say that people should sleep 6 instead of 8 hours. Readers of this comment can look at my essay and verify this for themselves.

3.

The commenter writes:

While some of walker's claims may be hyperbolic, I think they are within reason and justified by the important message he is trying to convey.

and

This is a book intended for the public, of course its not going to be written in a manner consistent with scientific discourse

Walker writes in Chapter 1 and I quote this in the introduction:

[T]his book is intended to serve as a scientifically accurate intervention

..and I quote "scientifically accurate intervention" two more times throughout the essay. I devote an entire section explaining this and showing that Walker even cites the book in his academic papers: https://guzey.com/books/why-we-sleep/#appendix-is-why-we-sleep-pop-science-or-is-it-an-academic-book-also-miscitations-impossible-numbers-and-walker-copy-pasting-papers

[–]Kinkajoe 7 points8 points  (6 children)

Yeah, agreed, a researcher shouldn't cite their pop science books in the publications. Regardless of what you think of walker as a human being, it doesn't diminish the validity of the recommendation for most people.

Your argument that Walker is a little too occupied with himself is valid, but that doesn't justify promoting borderline dangerous habits counter to most doctors' recommendations.

[–]guzeysci acc[S] 2 points3 points  (0 children)

Regardless of what you think of walker as a human being, it doesn't diminish the validity of the recommendation for most people.

I wrote a section about this: https://guzey.com/books/why-we-sleep/#appendix-the-concrete-harm-done-by-the-book

[–]guzeysci acc[S] 1 point2 points  (4 children)

Your argument that Walker is a little too occupied with himself is valid, but that doesn't justify promoting borderline dangerous habits counter to most doctors' recommendations.

Please point me to any specific passages in my essay where I promote "borderline dangerous habits".

[–]Kinkajoe 5 points6 points  (3 children)

Recommending 6 hours of sleep a night qualifies for me. You promote napping as necessary throughout the day if you feel tired, but this is impossible for most people and unreliable and humans are notoriously bad at self-rating their sleepiness and the effects this has upon their cognitive capacity.

[–]guzeysci acc[S] 7 points8 points  (2 children)

You write:

Recommending 6 hours of sleep a night qualifies for me. You promote napping as necessary throughout the day if you feel tired, but this is impossible for most people and unreliable and humans are notoriously bad at self-rating their sleepiness and the effects this has upon their cognitive capacity.

In the comment you replied to, I asked you to:

Please point me to any specific passages in my essay where I promote "borderline dangerous habits".

Can you quote me recommending 6 hours of sleep?

You promote napping as necessary throughout the day if you feel tired

Can you quote me promoting napping as necessary throughout the day if you feel tired?

Humans are notoriously bad at self-rating their sleepiness and the effects this has upon their cognitive capacity.

This is actually a good point. I added the following to the section about my personal experience with sleep:

If you decide to experiment with your sleeping habits, you can objectively assess the impact on your cognitive abilities using a site like Quantified Mind (a), which lets you design a battery of cognitive tests (on working memory, reaction time, executive control, mental rotation, and many others) to take and compare your results over time, while also allowing to track variables such as amount of sleep at every assessment.

[–]felagund08 1 point2 points  (1 child)

I'm afraid taking tests like Quantified Mind over time would lead not to fair comparison, but to training to succeed in such tests.

[–]guzeysci acc[S] 1 point2 points  (0 children)

Once you establish your baseline, Quantified Mind becomes a pretty good indicator of your current state, I believe.

Even if you're training over time, you'll notice deviation from a trend.

[–]guzeysci acc[S] 7 points8 points  (0 children)

Many of these criticisms are quite unfair or misunderstanding the science. I'll save this comment space until I can gather some papers and write up a more coherent argument against these claims.

Would love to read your critique!

edit: here's my response to the updated comment with the critique -- https://www.reddit.com/r/slatestarcodex/comments/dwtr0m/matthew_walkers_why_we_sleep_is_riddled_with/f7p3b2u/

[–][deleted] 2 points3 points  (2 children)

Thanks for your comment. I'm wondering, do you agree with Walker's comment here?

“Sleep is not like the bank, so you can't accumulate a 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 night 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 that you've been lumbering it with during the week in terms of a debt.”

Source

Because other's suggest it's possible,

The good news is that, like all debt, with some work, sleep debt can be repaid—though it won't happen in one extended snooze marathon. Tacking on an extra hour or two of sleep a night is the way to catch up. For the chronically sleep deprived, take it easy for a few months to get back into a natural sleep pattern, says Lawrence J. Epstein, medical director of the Harvard-affiliated Sleep HealthCenters.

Source

[–]Kinkajoe 2 points3 points  (1 child)

I don't think there's good data either way, especially in longer term contexts, to make a confident guess in either direction. My guess would lean towards something in between the two stances, based on some evidence from short term studies such as those listed below. You can recover from sleep restriction in certain cognitive and behavioral aspects, but this may not be the case metabolically. The longer term the sleep restriction, the more likely negative effects will continue onwards.

But sleep restriction is like drinking alcohol-sure it's not good for you, but the consequences from limited exposure are so little it's not going to push the needle enough to worry about it.

https://www.ncbi.nlm.nih.gov/pubmed/30827911/

https://onlinelibrary.wiley.com/doi/full/10.1046/j.1365-2869.2003.00337.x

https://academic.oup.com/sleep/article/33/8/1013/2454490

[–][deleted] 0 points1 point  (0 children)

Thank you!

[–]quick-math 2 points3 points  (2 children)

In fact, it is well documented that people very consistently underestimate the amount of sleep they get. This well-cited paper finds that people over-estimate the amount of sleep they get This well-cited paper finds that people tend over-estimate the amount of sleep

Thank you so much for the extended explanation from an expert. But what do you mean here: people under- or over-estimate sleep?

[–]Kinkajoe 1 point2 points  (1 child)

Corrected to 'over-report'. Thanks, that was definitely unclear

[–]whosyourjay 0 points1 point  (0 children)

I still feel it is self-contracting.

[–]Synopticz 3 points4 points  (4 children)

I don't study sleep. I consider Guzey's critiques quite serious. It is clear to me from this that Walker's book is problematic.

One of the things that recently got me thinking that sleep duration is probably overrated was learning about one of the major treatments for insomnia, which is sleep restriction therapy.

In this approach, people are encouraged to _decrease_ their sleep quantity, down to a minimum of around 5 hours, before raising it up gradually. Sleep restriction therapy tends to help depressive symptoms in people with insomnia: https://www.ncbi.nlm.nih.gov/pubmed/28619248

[–]how_to_choose_a_name 2 points3 points  (3 children)

Without looking deeper into the matter, it seems to me like the restricted sleep duration is a very temporary thing, meant to force your body to actually sleep instead of waking up at night so that more sleep is possible, and not in any way an indication that less sleep is generally beneficial.

[–]Synopticz 2 points3 points  (2 children)

From what I’ve read, a big part of what makes sleep restriction therapy helpful in the long run is helping people to realize that they dont need that much sleep to be productive/happy.

Promoting the idea that nearly everyone needs 8 hours of sleep even when/if they don’t has real harms. It causes people to become tense and can significantly contribute to insomnia. Eg https://www.reddit.com/r/insomnia/comments/7io4m1/my_insomnia_treatment_success_story/

[–]how_to_choose_a_name 2 points3 points  (1 child)

I haven't read about it much, my first impression is that sleep restriction therapy is not really about reducing the amount of sleep but about matching the time spent in bed to the time spent sleeping, i.e. if you only sleep 6 hours then you should not be in bed much longer than 6 hours. This would then cause your body to actually use that time for sleeping instead of waking up in the night or something?

[–]Synopticz 1 point2 points  (0 children)

Yeah that’s the idea!

A part of SRT is acceptance that it is okay to sleep less and that one will survive, rather than feeing like one must sleep at least 8 hours (or whatever the number is).

To me this seems consistent with Guzey’s critique of Walker’s book.

[–]mpbarry46 9 points10 points  (0 children)

The views are not equal.

Sleep is good for you

Alleged exaggerations or minor errors shouldn’t dissuade you against the bulk of the original book nor cause you to ignore the rest of the science discussed there

[–]DwightVSJim 2 points3 points  (1 child)

I feel like when it comes to any topic, someone could write an essay “debunking” it using many rhetorical tricks if they wanted.

[–]goyafrau 15 points16 points  (0 children)

I saw Matt Walker speak at a conference once and he came across as a huge blowhard who’d try to drown you in fancy figures (without error bars and largely unrelated to his actual claims: here isa picture of a sleep deprived brain, here’s a baseline brain, the sleep deprived brain is less colorful, ergo sleep makes you behave badly). Everyone else loved him though.

He seems like he’s in the sales department of a unicorn startup. Not a scientist.

[–]ownshoes 41 points42 points  (5 children)

The book goes over sleep deprivation therapy in quite some detail. The fact that a third of depressed patients can have a (temporary) boost to their mood through sleep deprivation does not counter the claim that sleep deprivation is bad for most people, most of the time. There is nothing contradictory in the quoted passages, unless taken wildly out of context. Didn't read the article beyond that because the author has misunderstood / is misrepresenting the book.

[–]ver_redit_optatum 7 points8 points  (0 children)

In this paragraph Walker definitely appears to be giving a treatment recommendation specifically related to the use of temporary sleep deprivation for depressed people, not just making “the claim that sleep deprivation is bad for most people, most of the time”:

As a result, sleep deprivation is not a realistic or comprehensive therapy option.

Does he prevent a more nuanced view later that guzey has cut off?

[–]guzeysci acc[S] 8 points9 points  (0 children)

does not counter the claim that sleep deprivation is bad for most people, most of the time.

I never wrote anything that contradicts "sleep deprivation is bad for most people, most of the time". If this is not true, please point me to a place in the essay where I write this.

[–]guzeysci acc[S] 6 points7 points  (2 children)

Walker writes: "the 60 to 70 percent of patients who do not respond to the sleep deprivation will actually feel worse, deepening their depression"

...in reality <10% of people will have their depression worsened from acute sleep deprivation while 40-60% will improve the symptoms. No contradictions and no misrepresentation by Walker, yes

edit: for those interested/suspecting I misrepresent Walker, here's the entire book's discussion of sleep deprivation therapy:

The swings in emotional brain activity that we observed in healthy individuals who were sleep-deprived may also explain a finding that has perplexed psychiatry for decades. Patients suffering from major depression, in which they become exclusively locked into the negative end of the mood spectrum, show what at first appears to be a counterintuitive response to one night of sleep deprivation. Approximately 30 to 40 percent of these patients will feel better after a night without sleep. Their lack of slumber appears to be an antidepressant.

The reason sleep deprivation is not a commonly used treatment, however, is twofold. First, as soon as these individuals do sleep, the antidepressant benefit goes away. Second, the 60 to 70 percent of patients who do not respond to the sleep deprivation will actually feel worse, deepening their depression. As a result, sleep deprivation is not a realistic or comprehensive therapy option. Still, it has posed an interesting question: How could sleep deprivation prove helpful for some of these individuals, yet detrimental to others?

I believe that the explanation resides in the bidirectional changes in emotional brain activity that we observed. Depression is not, as you may think, just about the excess presence of negative feelings. Major depression has as much to do with absence of positive emotions, a feature described as anhedonia: the inability to gain pleasure from normally pleasurable experiences, such as food, socializing, or sex.

The one-third of depressed individuals who respond to sleep deprivation may therefore be those who experience the greater amplification within reward circuits of the brain that I described earlier, resulting in far stronger sensitivity to, and experiencing of, positive rewarding triggers following sleep deprivation. Their anhedonia is therefore lessened, and now they can begin to experience a greater degree of pleasure from pleasurable life experiences. In contrast, the other two-thirds of depressed patients may suffer the opposite negative emotional consequences of sleep deprivation more dominantly: a worsening, rather than alleviation, of their depression. If we can identify what determines those who will be responders and those who will not, my hope is that we can create better, more tailored sleep-intervention methods for combating depression.

[–]Soldalis 2 points3 points  (1 child)

It still seems like a bad faith argument on your part. Walker's point is that in general, chronic long sleep is good for all body functions. Arguing that actually, acute sleep loss helps some people temporarily, while true, comes off as nitpicky to me. Sure, making a universal claim like "X always improves Y" is generally wrong. But providing a single small counterexample, then proclaiming that the whole book is of poor science quality, seems unjustified.

Point three about FFI seemed similarly nitpicky. Point five was slightly less nitpicky, but still.

On the other hand, points 4 and 1 were fairly convincing. Walker clearly makes up claims or outright misreports evidence.

All in all I wasn't too dissuaded by your review. Maybe Walker misattributes or misreports some of his evidence. But the main claim he's making (8 hours sleep good) doesn't seem too controversial, and I imagine most of the evidence he cites is properly attributed and properly reported. He's a Berkeley researcher after all. In contrast, Stephen Gundry's The Plant Paradox made a fairly ridiculous claim (many vegetables bad) AND suffered from shoddy science reporting. THAT is a case where the whole book should be thrown out. But that doesn't seem to be the case here.

I'm excited for Red Pen Reviews to do this book, if they do.

[–]guzeysci acc[S] 4 points5 points  (0 children)

It still seems like a bad faith argument on your part. Walker's point is that in general, chronic long sleep is good for all body functions. Arguing that actually, acute sleep loss helps some people temporarily, while true, comes off as nitpicky to me.

Here's the Walker's quote I provide:

[W]e are now forced to wonder whether there are any biological functions that do not benefit by a good night’s sleep. So far, the results of thousands of studies insist that no, there aren’t.

I invite readers to judge whether Walker is talking about chonic long sleep or by a single night of good sleep.

[–]wdtpw 34 points35 points  (3 children)

Claim:

In another instance, Walker seems to have invented a “fact” that the WHO has declared a sleep loss epidemic.

Some google searching later:

A research paper, entitled, Sleep Problems: An Emerging Global Epidemic? Findings From the INDEPTH WHO-SAGE Study Among More Than 40,000 Older Adults From 8 Countries Across Africa and Asia

An aside: here's a paper from the CDC calling sleep an epidemic, too

My conclusion: not unreasonable to say the WHO has called lack of sleep an epidemic.

I haven't looked into anything else, and I just picked one claim out at random because it seemed like it would be easy to validate. But from that single data point, I'd say the article is not completely rigorous in its own analysis so as a result, I'm not at all sure how much to trust any of it.

[–]PlasmaSheeponce knew someone who lifted 8 points9 points  (2 children)

Which of these papers shows that the WHO has called lack of sleep an epidemic?

[–]wdtpw 7 points8 points  (0 children)

I'm finding this a difficult question to answer, so I'll have to split my answer in three parts.

a) Yes. You are correct. It's not an official WHO position.

but, I'll temper this by:

c) I understand how Walker might have seen a paper saying, "findings from a WHO study," and thought it was a WHO position. I did, after all.

... and also:

c) As another commentator has said, changing 'WHO' to 'CDC' doesn't affect the actual case very much. To say organisation X thinks something, when it's really organisation Y is only significant if organisation Y is thought of as a less weighty body. In this case, I'd consider both the WHO and the CDC to be fairly authoritative on health issues, so I'm stuck on 'it's a difference, but is it one that matters?'

But I ought to be honest, so I will reiterate ( a ) once more. On that point, you are correct and I was wrong.

[–]a_random_user27 9 points10 points  (0 children)

I guess the correct claim would be that CDC, rather than WHO, has called the lack of sleep an epidemic. I agree its important to be correct about the facts, but here changing "WHO" to "CDC" doesn't seem to alter much the case the author is trying to make.

[–]INeedAKimPossible 10 points11 points  (0 children)

I spent more than 130 hours over the last 2 months researching and writing this essay

Well, I'm glad someone is willing to do the work. Thanks for your contribution.

[–]Ilforte 10 points11 points  (0 children)

This is a curious case. I wonder why Walker even felt the need to embellish his claims, and how it passed by scientific editors. Perhaps a debunking of this kind is necessary to establish a higher standard of rigor in popular, clinically consequential texts so that they have unassailable authority. Misplaced empathis, exaggerated confidence in specific details, flat-out doctoring evidence to make your case stronger – surely those are sins. Yet it feels insufficient to condemn the book. Walker's basic message (namely "sleep is important and many people are lacking it") still resonates with me, who's near-constantly sleep-deprived for no decent reason, feels like crap and writes this watching as the dark sky begins to turn blue. As far as I know, there are heaps upon heaps of papers which show different sides to the problems of partial sleep deprivation, unstable sleep cycle and sleep disturbances. On the other hand, our very own Scott has shown us a few times how respectable paradigms crumble like cookies and their "peer-reviewed articles" turn to pumpkins. On the other other hand, the vast epidemiological data is tainted by our inability to determine causality, such as with all-cause mortality or inflammation markers: does the habit of (somewhat) shorter sleep benefit people, or are 7-hour-sleepers just naturally more healthy to boot? Or maybe it mediates SES such that there's a nonlinear tradeoff between benefits from career investment and health problems? I guess we need to figure out what counts as a decent natural longitudinal experiment.

Would I feel the same way on any other topic? Would I even dare voice such vague, handwavy disagreement here? Ironically I, like u/Kinkajoe, study sleep. However I haven't yet read Walker's book and thus do not consider it reasonable to respond to guzey's take in isolation, going into an endless regress of nitpicking (in the meantime I'll lazily wait for Kinkajoe's writeup). Overall, this could be a good adversarial collaboration topic, if only guzey weren't so outgunned (people who choose to sacrifice sleep for productivity and don't think it's a health risk are numerous, but have yet to awaken to their class consciousness).

Maybe something more prescriptive will be produced as a result.

[–]symmetry81 19 points20 points  (4 children)

I'll repost my two star review from Goodreads here:

Eh, lots of good stuff but it seemed like it was talking down to me and had a lot of problems with oversimplifying and... distorting the truth so as to try to be as convincing as possible. For instance it argues in one place that it's vitally important to get 8 hours of sleep a night because catch-up sleep on the weekend just doesn't work. But it also argues that it's a crime that some parents deprive teenagers of vitally important catch-up sleep on weekends. And in another place it argues that lack of sleep changes our genomes! But then clarifies that it really changes our gene expression, but doesn't mention all the other common things that change our gene expression, like eating. So I really didn't feel like I could trust it in areas where I couldn't verify.

[–]mpbarry46 4 points5 points  (3 children)

Fair criticism though sometimes when educated people ramble they tend to make more mistakes but there can still be a lot of learning from them

[–]symmetry81 9 points10 points  (1 child)

Yes, but ideally the reason one reads books rather than watching people rant on YouTube is that they and their editor should prevent these sorts of thing.

[–]mpbarry46 1 point2 points  (0 children)

Agreed and wish they had

[–]Reddit_is_therapy 1 point2 points  (0 children)

Yes, but it also means that a reader is more likely to interpret some false information as credible just because it came from an educated person, and cause a far greater harm than what he/she set out to prevent in the first place. Also, they won't be scientifically accurate when teaching other people about that, and the misinformation spreads.

[–]0mnus 9 points10 points  (0 children)

So happy someone finally wrote about this. I read the book and it didn't pass the smell test - it seemed like he just wanted to be considered an "expert" on sleep and get invited on daytime talk shows, etc.

In particular, the book literally never addresses the question in its title. It is simply a collection of cherry picked studies that tell us about what happens when we sleep. But to answer the "why," question you would have to give an explanation in terms of evolutionary fitness, and that would have to further explain why sleep was more advantageous than other "options" that didn't involve becoming vulnerable and comatose for 1/3 of the day (or much longer for some animals).

[–]keeper52 4 points5 points  (10 children)

The parts of this essay that explain why we shouldn't treat Walker as a reliable source of information about sleep seem pretty strong. I will look for other sources if I decide that I want to learn more about sleep. (Any recommendations?)

The parts of the essay which give advice about sleep seem much less strong. The conclusion (section 8) says "If you take one thing away from this entire essay, remember this: as long as you feel good, sleeping anywhere between 5 and 8 hours a night seems basically fine for your health." This takeaway is poorly supported by the essay, which doesn't even try to look into what studies sleep researchers have done to attempt to tease apart correlation and causality.

[–]guzeysci acc[S] 2 points3 points  (9 children)

Hi! Thanks for the feedback. I don't know any good books about sleep (but I haven't really searched for them). It seems that we don't know much and my expectation is that just like elite athletes know more about nutrition than do nutritionists ...

This takeaway is poorly supported by the essay, which doesn't even try to look into what studies sleep researchers have done to attempt to tease apart correlation and causality.

Could you point me to any such studies? This takeaway is based on expectation that if it were dangerous for one's health, we would have some significant increase in mortality of short-sleepers, but as I show on figure 1, people who sleep anywhere between 5 and 8 hours (maybe even 4) have pretty much the same mortality, with those reporting 7 doing a little bit better than the rest.

[–]keeper52 1 point2 points  (8 children)

The correlational graph that you showed doesn't tell us all that much. For one thing, casual experience suggests that different people "need" different amounts of sleep. If people who sleep 5 hours are mostly the ones who only "need" about 5 hours, then their outcomes don't tell us much about what would happen if someone who "needs" 8 hours of sleep decided to reduce their sleep. For another, factors like illness can change a person's sleeping patterns (while also influencing health outcomes).

I don't have much familiarity with sleep research and can't point you to any studies.

I imagine that there are a bunch of sleep studies which involved bringing people into a sleep lab, varying things related to their sleep, and measuring various outcomes. And it seems like researchers should be doing instrumental variables studies, like using variation in school start times to see if students whose sleep is exogenously reduced (due to school starting earlier) have worse outcomes.

I would like to be getting advice on sleep from people who know if these sorts of studies exist and have looked into their methodology and results.

In general it's much easier to evaluate a source than to figure out what's true about a topic. Sometimes it just takes a few minutes of reading to recognize that someone is reasoning poorly & playing fast and loose with the evidence, and therefore should not be trusted as a source of information. But knowing to downgrade that source typically doesn't tell us much about what's actually true about the topic that they're discussing. Your work involved a much more thorough & time-consuming evaluation of the source (which was useful because the source had a bunch of apparent credibility), but it was still mainly directed at the question of how much to trust this source and doesn't seem to tell us much about what's actually true about sleep.

[–]guzeysci acc[S] 0 points1 point  (7 children)

If people who sleep 5 hours are mostly the ones who only "need" about 5 hours, then their outcomes don't tell us much about what would happen if someone who "needs" 8 hours of sleep decided to reduce their sleep.

Yes! This is why I write "as long as you feel good, sleeping anywhere between 5 and 8 hours a night seems basically fine for your health" and explicitly note that I'm not saying that there are no people who naturally need 8 hours of sleep a night

And it seems like researchers should be doing instrumental variables studies, like using variation in school start times to see if students whose sleep is exogenously reduced (due to school starting earlier) have worse outcomes.

I believe there are a bunch of such studies by the economists but can't point to anything in specific.

but it was still mainly directed at the question of how much to trust this source and doesn't seem to tell us much about what's actually true about sleep.

Yep

[–]keeper52 2 points3 points  (6 children)

'If you feel good then you're probably getting enough sleep for your health' seems like a pretty good lay theory, but it's the sort of view that someone can have without looking into sleep research at all. It (in combination with the 5-8 hour range) seems like plausible advice, but it doesn't seem like a conclusion that has been well-supported by an essay that points out things that Walker got wrong.

[–]guzeysci acc[S] 0 points1 point  (5 children)

This is a good point, however I'm not aware of any method of figuring out one's sleep requirements, aside from "enough to not feel sleepy". Would love if anyone pointed me to any other markers..

Let me try to summarize and let me know if I get something wrong:

  1. you say that we don't know what happens if someone who needs to sleep 8 hours reduces their sleep to 5 hours (I agree 100%), therefore my claim about anywhere between 5 and 8 being fine is not supported
  2. I point out that I note "as long as you feel good"
  3. you point out that this might not be a good marker for the actual sleep requirements
  4. I point out that this seems to be the only marker we have (although this by itself is a weak argument ("garbage in garbage out"))

I agree with you that if this is actually a bad marker for how much sleep we need, this sentence is invalid, therefore, I note in the next sentence:

All of the evidence we have about sleep and long-term health is in the form of those essentially meaningless correlational studies

[–]mimkorn 1 point2 points  (4 children)

Actually one of the studies Walker mentions is the one where "feeling you had enough sleep when you hadn't" is not a reliable way to tell if you had they had experiment where they evaluated cognitive abilities of ppl with lack of sleep who self reported as feeling fresh. They consistently underperformed with reliable significance factor

[–]guzeysci acc[S] 1 point2 points  (3 children)

Does he give a citation or enough identifying information about the study for me to take a look?

[–]mimkorn 1 point2 points  (2 children)

You are very right, this was something that annoyed me very much in the book, cause there were studies he mentioned I wanted to look at, but really no citations and even a good amount of attempts to look for them with reasonable keywords did not provide satisfying results. That's really a shame.

However, I'm inclined to believe that it's out there, but not cited. It's bad practice, however and walker would do better to cite all sources in some response to your efforts. Did you try to reach out to him? He seemed to be open to conversations.

[–]guzeysci acc[S] 1 point2 points  (1 child)

  1. I'm inclined to disbelieve him. As I note in the essay, he misrepresents a ton of things. For studies I was able to identify he seems to literally inflate their sample sizes and to selectively cite their findings. Did you look at https://guzey.com/books/why-we-sleep/#appendix-a-strong-contender-for-the-single-most-absurd-paragraph-in-the-book ? I don't see why in the case of the study you're talking about I would believe him. In one of the studies I discuss in the link, he appears to cite one significant statistic disregarding the fact that total cardiovascular mortality was unchanged and I see no reason to think that in that cognitive ability study he didn't do something similar, citing one statistic out of context.
  2. You can check impact of sleep deprivation on youself! Use http://quantified-mind.com/ or something similar. This site lets you design a battery of cognitive tests (on working memory, reaction time, executive control, mental rotation, and many others) to take and compare your results over time, while also allowing to track variables such as amount of sleep at every assessment. When I slept for 6 hours a night with no naps for 5 days, I felt pretty bad, but there was no difference in my cognitive scores, compared to the baseline.
  3. Dozens of people contacted Walker about my essay (https://twitter.com/search?q=%40sleepdiplomat%20%40alexeyguzey&src=typed_query) -- he has not responded yet.

[–]throw_my_username 5 points6 points  (15 children)

I liked your article, except for this part:

However, let me make an analogy: when people don’t restrict their food-eating, many of them start eating more than they need and become obese, meaning that simply allowing ourselves to get as much food as we want, likely isn’t the healthiest choice. My guess is that same is likely true for sleep.

I call BS. This is an awful analogy. Sleep and food intake are completely different beasts. One does not "decide" how much sleep to get the same way one does not "decide" how fast his own heart should beat. The same cannot be said about food, where you always are in control of how much you eat - and, in fact, it's not that people will "overeat" if they are let to, it's the fact that our food nowadays is absolute garbage and packed-full with extremely high-calories.

Apart from this, I did like your article and made me change my opinion on Walker (though I still regard sleep as super important)

[–]guzeysci acc[S] 0 points1 point  (14 children)

Hmmmm, my mind is ready to be changed but I'm not sure I buy your argument. You can absolutely decide how much sleep to get. Suppose you need 8 hours of sleep a night. You can long-term stay in bed for 7 hours or for 8 hours or for 9 hours. Same for food. Suppose you need 2000 calories a day. You can long-term eat 1500 calories or 2000 calories or 2500. Your health will be different at every level but all of these are sustainable

[–]throw_my_username 0 points1 point  (13 children)

stay in bed

I think the distinction is important. Stay in bed != being (naturally) asleep.

Yes, you can decide how much to eat because you, your conscious self decides. You could eat nothing or eat a lot of calories (up to a point, such as the physical size of your stomach).

When it comes to actual sleep though (not simply time in bed), the only choice you have is as follows: to use an alarm clock to short-circuit your natural sleep duration. This is something most people do. What happens when people are in the weekend / don't use an alarm clock? Generally their sleep increases to the average of 7-9 hours and the body itself regulates how much of it it needs.

Even if you wanted you couldn't sleep (regularly) 15 hours a day. Our bodies just aren't built like that. Just like you can't eat more than the physical space in your body, otherwise you'd just pass out / throw up.

You can long-term eat 1500 calories or 2000 calories or 2500. Your health will be different at every level but all of these are sustainable

Agreed. What I don't agree on is the tone of that section of your article. You make it seem as though people sleeping 9 hours (naturally) are going to get "obese" because they could very well do on just 8 hours. That's not true. While you can eat above your caloric maintenance and become obese, you can't "oversleep" and become "sleep-obese" in the same way, because you do not control how much sleep you "eat", as it is involuntary (in duration).

This means that when it comes to sleep, you can only do two things: wake up with alarm clocks and screw up your natural sleep need OR sleep at maintenance and enjoy the benefits of sleep. There's no third option of "oversleeping" (in normal, regular circumstances)

[–]guzeysci acc[S] 0 points1 point  (12 children)

I don't think there's any evidence that screwing up "natural" sleep with alarms is bad and my anecdotal experience suggests the opposite.

[–]throw_my_username 0 points1 point  (3 children)

Well, this comment now makes me question everything else in the article. Might need to do my own research 😩

[–]guzeysci acc[S] 0 points1 point  (2 children)

haha, would love to see what you find!

[–]throw_my_username 0 points1 point  (1 child)

Well, pretty easy [1]

Another problem is thought to be the increased risk of a coronary heart attack related to the daytime nap 11–14) . Acute increases in heart rate and blood pressure at awakening are associated with these problems 15) . When we awaken by means of external stimuli such as an alarm clock or someone’s voice, our blood pressure and heart rate would increase, and these changes might trigger a heart attack.

Also, in this comment (emphasis mine):

Yes, I believe you can. If you naturally sleep for 8 hours, you can go mildly sleep derprived for as long as you want on 7 hours of sleep or you can stay in bed longer then you should and probably get additional 30-60 minutes of sleep, also for an indefinitely long time

You're basically admitting that you'd be sleep deprived the entire time (with the 100s of negatives that that entails). Thanks, but I like doing everything I can to prevent alzaimers/heart disease/etc, like sleeping as much as my body wants.

Thanks for confirming you don't know what you're talking about for everyone else that might read this.

[1] https://www.jstage.jst.go.jp/article/indhealth/43/1/43_1_179/_pdf/-char/en

[–]guzeysci acc[S] 0 points1 point  (0 children)

did you read section 1 of my essay? I covered all your arguments there already. Everything you're talking about is correlational studies.

When we awaken by means of external stimuli such as an alarm clock or someone’s voice, our blood pressure and heart rate would increase, and these changes might trigger a heart attack.

Following this argument exercise is bad for you. It raises blood pressure and heart rate and might trigger a heart attack

[–]usehand 0 points1 point  (7 children)

Wait, so how do you suggest sleeping less than 8h without an alarm?

[–]guzeysci acc[S] 0 points1 point  (6 children)

Did I?

[–]usehand 0 points1 point  (5 children)

I didnt mean to say you recommended sleeping less than 8h, but I thought you suggested it would be possible to choose how much to sleep (within reasonable boundaries) here:

You can absolutely decide how much sleep to get. Suppose you need 8 hours of sleep a night. You can long-term stay in bed for 7 hours or for 8 hours or for 9 hours.

[–]guzeysci acc[S] 0 points1 point  (4 children)

Yes, I believe you can. If you naturally sleep for 8 hours, you can go mildly sleep derprived for as long as you want on 7 hours of sleep or you can stay in bed longer then you should and probably get additional 30-60 minutes of sleep, also for an indefinitely long time

[–]usehand 0 points1 point  (3 children)

Sure, what I was wondering was how would you go about sleeping 7h (or anything less than you "naturally" would) without using an alarm?

[–]guzeysci acc[S] 0 points1 point  (2 children)

Oh I got you. I meant that you can choose how much you sleep by using an alarm.

[–]digitalnomadic 20 points21 points  (14 children)

Out of all of the claims and detail in the book, these seem extremely minor.

[–]guzeysci acc[S] 3 points4 points  (13 children)

You think that inventing a "sleep loss epidemic" and then saying that the WHO has declared a sleep loss epidemic is minor?

You think that misrepresenting the sleep guidelines while claiming that your book is scientifically accurate is minor?

You think that saying that a lack of sleep will kill you when it's just not true is minor?

You think that saying that sleep deprivation therapy deepens depression in 70% of people when in reality this happens in less than 10% of cases is minor?

You think that saying that shorter sleep means shorter life when in reality your recommendation has higher mortality than at either 5, 6 or 7 hours is minor?

These were the 5 main points I covered in the essay.

[–]abolish_the_divine 3 points4 points  (0 children)

people repeat these claims a lot from what i've seen.

[–]wdtpw 3 points4 points  (11 children)

You think that inventing a "sleep loss epidemic" and then saying that the WHO has declared a sleep loss epidemic is minor?

Is it an invention, though? Some google searching provided the following for me:

[–]guzeysci acc[S] 11 points12 points  (0 children)

I updated the essay indicating that CDC could have been the origin of Walker's epidemic: https://guzey.com/books/why-we-sleep/#possible-origin-of-the-sleeplessness-epidemic-thing

[–]guzeysci acc[S] 9 points10 points  (2 children)

I'm surprised that you believe these links are relevant. As /u/fubo pointed out, the first paper doesn't have anything to do with WHO, aside from the fact that it used some WHO public data.

The second link is by CDC, not WHO.

[–]DwightVSJim -2 points-1 points  (1 child)

Who is saying this was the WHO source that he is even referring to?

[–]AlcherBlack 1 point2 points  (0 children)

Walker literally writes "the World Health Organization (WHO) has now declared a sleep loss epidemic throughout industrialized nations." on page 4 of the book...

[–]fuboso we read and we watched all the specially selected news 8 points9 points  (6 children)

The first is not a statement from WHO; it is a Betteridge-flagged article, chiefly by authors at the University of Warwick, analyzing a data set published openly by WHO. The headline is the responsibility of the authors and editors, not WHO.

The second is not a statement from WHO, either.

Neither one, therefore, makes the statement "WHO has declared a sleep loss epidemic" anything other than a false statement.

It would be true to say that CDC published a Word document calling insufficient sleep a public health epidemic. But apparently that true claim was not sufficient for Walker's rhetorical purposes.

[–]digitalnomadic 18 points19 points  (5 children)

Yea I think the errors found are pedantic and seem symptomatic of someone who read the book with the express intent of trying to find errors and to discredit the author. This is a great example.

[–]Noumenon72 5 points6 points  (0 children)

I disagree with your approach to critical thinking as "trust the author and don't let their obvious inattention to factual accuracy dissuade you from that". When you look deeply into claims from people who are worth reading, you usually find facts that are true and well supported, because people who are actual experts on a topic tend to have a deep knowledge base and care about getting the details right.

It's easier for an expert to catch a wrong claim, because they know so much that it doesn't fit with other facts they know. So someone who lets a lot of bullshit slip through is probably not as credible as they sound.

[–]fuboso we read and we watched all the specially selected news 5 points6 points  (3 children)

I don't know, I think if I could say a true thing by saying "CDC said X" or a false thing by saying "WHO said X", I would want to say the true thing. I don't think that's a super weirdly high standard.

But then, I was in middle school when I took a logic course that talked about speech acts such as claiming or declaring, so that may have been unusually formative for me.

[–]FeepingCreature 3 points4 points  (2 children)

The devil's advocate for "WHO said X" would be that for rhetorical purposes, WHO and CDC are largely interchangeable. Most casual readers would not react significantly differently to those two sentences, so while as a statement of fact it is completely wrong it mostly does the same work as an argument, since the argument is "a big health organization takes this seriously." It's kind of a Gettier argument.

[–]how_to_choose_a_name 6 points7 points  (1 child)

It's still pretty dishonest though and definitely should be pointed out. He should have just written that it's the CDC or even just "a big health organization" and then pointed out the exact organization in a footnote. But writing that the WHO declared it makes it seem like he's just using the prominence of the WHO to make his claims seem more trustworthy. Using such methods should always be discouraged, no matter if the claims are true or not.

Also, the WHO operates on a broader scope than the CDC, being international and all. That doesn't make the CDC any less of an authority, but it means that the CDC is very US-centric and when they declare an epidemic based on data from the US that might or might not mean anything for the rest of the world. Claiming the WHO declared an epidemic makes it sound like a worldwide problem though.

[–]FeepingCreature 2 points3 points  (0 children)

I agree that it's misleading in that sense.

[–]MisterHoppy 2 points3 points  (8 children)

Hmm. I was looking into Matthew Walker a bit and it seems odd that where he claims he got his PhD on his own website (the MRC in London, very prestigious) is clearly not where he got his PhD: both his thesis and wikipedia page show that his PhD was from the University of Newcastle upon Tyne (less prestigious). A contemporaneous publication shows his affiliation as "MRC Neurochemical Pathology Unit, Newcastle General Hospital, Newcastle upon Tyne, UK".

Was he just sloppy in writing up the bio on his own website? Or stretching the truth to tell a better story? This seems reminiscent of the issues that /u/guzey and others are grappling with in this thread.

[–]guzeysci acc[S] 2 points3 points  (7 children)

This is very interesting. Could you email MRC and ask for a confirmation that Walker received his PhD there? https://mrc.ukri.org/about/contact/ https://loop.frontiersin.org/people/198/bio -- this bio lists MRC, London This paper from 1999 lists Newcastle http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.409.2558&rep=rep1&type=pdf

[–]ImOpAfLmao 4 points5 points  (5 children)

The MRC funded his research, so I'm assuming that's what he means by PHD from MRC. The MRC funds PHD research, it's not a university - I suppose his website should instead say "PHD from Newcastle University with funding from the MRC".

[–]guzeysci acc[S] 2 points3 points  (4 children)

If this is true, this is a serious misrepresentation. "funded" by seems completely different from getting the PhD by. If you're funded by NIH you never write "got my PhD at NIH".

Do you have a source for your funded by MRC thing?

[–]ImOpAfLmao 2 points3 points  (3 children)

Sure, but since getting a PhD at the MRC makes no sense, I'm assuming he wasn't trying to act like he got his PhD there (it's a lot different than, say, saying you got your PhD from Stanford, if Stanford just funded your research and you actually got it elsewhere, since getting a PhD from Stanford can actually be done).

I can't find an explicit source that says his PhD was funded by the MRC, but here is a paper from 1999 with the footnote verifying that MRC is related to this paper, and I'm assuming this was part of his PhD work: http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.909.4525&rep=rep1&type=pdf

[–]guzeysci acc[S] 2 points3 points  (2 children)

On the one hand, yes, on the other hand, his site literally says https://www.sleepdiplomat.com/professor :

Dr. Walker earned his degree in neuroscience from Nottingham University, UK, and his PhD in neurophysiology from the Medical Research Council, London, UK.

No mention of Newscastle. This 100% seems like he got his degree from MRC **London** to everyone except for a small number of people who are not aware that this is not a degree-granting institution.

[–]ImOpAfLmao 2 points3 points  (1 child)

Agreed. Although, look at the footnote on the first page: it mentions newcastle there, (albeit the hospital, not the university), but his email address is presumably from newcastle: (@ncl.ac.uk).

And under the acknowledgements, they acknowledge the MRC for supporting the project.

[–]guzeysci acc[S] 1 point2 points  (0 children)

Yep, no problems with the paper! Affiliations there seem legit.

[–]Muskwalker 2 points3 points  (1 child)

I have not investigated Walker’s claims about sleep and learning, since he does not make any concrete statements about this in Chapter 1. However, is there any reason to expect his treatment of sleep and learning to be any more accurate than, for example, his treatment of the relationship between sleep and longevity?

Could the answer to this actually be "yes"?

The possibilities are a) "Walker* is an accurate expert on all areas of sleep science", b) "Walker is an accurate expert in some areas of sleep science but not in others", and c) "Walker is a not an accurate expert in any area of sleep science at all". This essay lowers our assessment of the probability of (a) (and a statement like the one here quoted seems to specifically disclaim attempts to provide evidence lowering our prior on (b)). So then couldn't our assessment of (b) and (c) both actually rise?

For example, say my priors were p(a) = 10%, p(b) = 60%, p(c) = 30%**— and I estimate the probabilities of a debunk like this occurring at p(D|a) = 10%, p(D|b) = 75%, p(D|c) = 90%†‡ — then the updated probabilities are p(a|D) = 1%, p(b|D) = 62%, p(c|D) = 37%; my assessment that he's an accurate expert in every area of sleep science goes way down and my assessment that he might be a charlatan goes up, but so does my assessment that whatever accurate expertise in sleep science he may have lies elsewhere.


* No relation.
** "Prone to be skeptical of medical experts, even more skeptical of one having both broad and deep knowledge, but recognizing that apparently people do recognize him as expert enough to publish and cite this work"
† "It'd be hard to debunk a truly accurate expert, easy to debunk a charlatan, and easy to find shaky areas to debunk, though maybe less likely that those would be in any particular chapter, though maybe more likely in a chapter 1, which tends to be synoptic"
‡ I admit it is true that values for these could be held that will lower one's value of the probability of 'b' given the debunking.

[–]guzeysci acc[S] 2 points3 points  (0 children)

Of course it could! As you correctly point out, the right priors can fix anything :)

[–]fmlpk[Put Gravatar here] 4 points5 points  (2 children)

When I first heard him, I felt something was off but couldn't really point it out. It's in ways a bit similar to the very extreme forms of climate activists who basically want to shut every factory down.

Also most people who rise to fame due to rogan have a very high chance of being bro scientists. Not calling matt one but rogan probably could not have debunked the claims mentioned here

[–]INeedAKimPossible 5 points6 points  (1 child)

Of course not. This is not a knock a Joe, but he has a hard time following logical arguments, as evidenced by his Nick Bostrom interview.

[–]fmlpk[Put Gravatar here] 4 points5 points  (0 children)

Joe is someone who needs to know something about most things in order to run his podcast.

I have been a big fan for years but he can unknowingly promote bro science like the time he had Ben greenfield, scibabe and whatnot

[–]betaros 7 points8 points  (12 children)

Haven’t read the book so I wont speak to its accuracy, however the guy seems to be punching above his weight. He gives a bunch of credentials for Mathew Walker, but none for himself. Presumably if the popular book was incredibly inaccurate there would be someone more invested in the field who would complain. I’m a little suspicious of his analysis considering that he suggests that 5 hours of sleep is as good as 8 hours based on a comparison of mortality. I haven’t looked into it but it conflicts with my prior that 8 hours more or less is recommended.

[–]Ilforte 7 points8 points  (2 children)

there would be someone more invested in the field who would complain

I'll liberally translate a respectable sleep researcher, from an email discussing pdf of a localized edition:

«Thanks! This Walker is a clinician, which explains his approach. You see him referencing only clinicians, and mainly his associates at that. The works of other authors, especially ours [Russians], he quotes without reference. But in general it's interesting, we should read it diligently.»

This is what concerns people more invested in the field than guzey. I'm not judging, the person I quote is decent to his peers, competent and does good work (in my opinion). But he doesn't really have any incentive to produce a takedown.

[–]betaros 4 points5 points  (1 child)

I disagree. Scientists review pop-sci books all the time, especially the popular ones. This book received a lot of media attention and scientists especially ones in such applied fields have an interest in a correctly informed public. In fact a former BMJ editor gave Why We Sleep a generally positive review:

https://blogs.bmj.com/bmj/2018/06/20/richard-smith-why-we-sleep-one-of-those-rare-books-that-changes-your-worldview-and-should-change-society-and-medicine/

Look at r/AskHistorians as another example of (scholars) shitting on "popsci" in their "Historians' view of other Historians" section of their FAQ page. So I don't by the idea that all the scientists care about is references.

[–]Ilforte 2 points3 points  (0 children)

You're disagreeing with your fallacious interpretation: I do not make a general claim about "scholars". And this BMJ guy is not a narrow specialist either.

Somnology is a tiny insular world, with pensive cooperation yet some disagreement between medical and scientific sides. Uncharitably, all parties involved are interested in keeping the public more nervous than "correctly informed", because as of now, the public cares very little either way and provides almost no income. That, and references of course. Nitpicking at the only high-profile book promoting sleep research awareness in years, possibly ever? In your dreams.

But well, the more charitable hypothesis is that guzey's critique is irrelevant and the luminaries with credentials have just agreed with Walker. I suppose it's a fine prior to trust their assumed silent endorsement.

[–]ver_redit_optatum 2 points3 points  (7 children)

What is your “prior” based on?

[–]betaros 6 points7 points  (5 children)

As I mentioned I haven’t looked into it, but this I think is “common knowledge” from before the publishing of the book. Quickly googling suggest that the 7-9 hour range is supported with more suggested based on age. I’m not interested enough to look into this deeply, the analysis there was just a bit of a red flag for me, but maybe he’s right.

Edit link: https://www.mayoclinic.org/healthy-lifestyle/adult-health/expert-answers/how-many-hours-of-sleep-are-enough/faq-20057898

[–]Noumenon72 5 points6 points  (2 children)

I think your prior should be that health advice is much more in demand than supply and people make up all kinds of unsupported rules. 8 glasses of water, high heels shorten your calves, skim milk, daily vitamins, nothing holds up to a critical take. It's not like evolution or math where the received wisdom is based on more and more detailed proofs.

[–]betaros 2 points3 points  (1 child)

Granted not all common knowledge is correct, that said it is a reasonable starting point for someone who has not conducted research. Additionally part of my prior is confidence in my critical thinking ability. Not all common knowledge is created equally. As an example the 8 glasses of water idea doesn't really mesh with what I do or see other people do on a sedentary day. Not to mention that the amount of water is not nearly as much as I would drink if I were outside all day. On the other hand 8hrs of sleep seems fairly reasonable. It's about how many hours I would naturally sleep, and I ofter see students who get less sleep show symptoms such as baggy eyes and falling asleep in class. When I don't get enough sleep I similarly feel sleepy so this common knowledge is much more believable. Also notice the link in the edit found from a quick google search.

[–]Noumenon72 1 point2 points  (0 children)

I did read the link before replying, but since it has no sources, it is like you say only "a reasonable starting point for someone who has not conducted research". As is "that's how much I normally sleep and people who sleep less seem tired". I think you need to take your critical thinking to the next level and start asking questions like "Why doesn't the mortality data agree with Mayo's claim? Do they have other sources, and why didn't they provide them? If there were people who were getting less sleep and weren't falling asleep in class, would I have any way to notice that and update my theory, since I can't actually see how much sleep people get?"

The reason I like Slate Star Codex is that Scott is very good at exemplifying this kind of critical thinking, and has taken down many naive conventional recommendations over the years.

[–]ver_redit_optatum 3 points4 points  (1 child)

I mean, the whole reason to engage with the type of material we discuss on this subreddit is to potentially find deeper analysis that challenges our “common knowledge”. It’s surprising how often some bit of commonly known scientific wisdom is actually just a series of Chinese whispers coming from misquotes, papers that really didn’t show that at all, and journalistic exaggeration.

[–]betaros 0 points1 point  (0 children)

See my reply to u/Noumenon.

[–]mpbarry46 0 points1 point  (0 children)

Attempted takedown given from the viewpoint of someone who wants sleep deprivation to work, questioning something that doesn’t need to be questioned - the benefits of high quality sleep are vast and well established

[–]bassuvius 1 point2 points  (0 children)

So this is a small side thing but I’m just finishing Why We Sleep and also just finished Midnight in Chernobyl by Adam Higginbotham and in Matthew’s Why We Sleep he states that it was the scientists lack of sleep that caused the Chernobyl disaster when in the thoroughly researched Midnight in Chernobyl that is obviously far from what caused the disaster. How can an author make such a huge claim like that? If I wouldn’t have read the other book I would have taken it for the truth. Anyway like I said just something I noticed since I happened to just finished both of these books. Carry on.

[–]zappable 0 points1 point  (0 children)

Walker's book exaggerates the problem of getting less than 7 or 8 hours of sleep. This fear-mongering could be beneficial in encouraging people who can easily sleep more than 5 or 6 hours to do so. But it's harmful for people who have trouble sleeping more than e.g 6 hours since then they worry about it more than necessary and it can even harm their sleep.

[–]UnlikelyDocument 0 points1 point  (0 children)

platonism

[–]Life_Of_David 0 points1 point  (0 children)

Thanks for this, I skimmed it but the potential harm section was great. I won’t be to focused on 8 hours, I’ll keep shooting for 7. Most nights I get 6 but this book had me about to waste time on getting 8 like you said, and I’d rather have more time in my life.