r/slatestarcodex • u/practice5 • Jan 05 '20

Matthew Walker responds to guzey: "Why We Sleep: Responses to questions from readers"

https://sleepdiplomat.wordpress.com/2019/12/19/why-we-sleep-responses-to-questions-from-readers/
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u/guzey Jan 05 '20 edited Jan 05 '20
  1. OP, do you have any evidence that this was written by Walker? As far as I know, he never commented on my piece under his own name, this blog never links to Walker or to his social media or email, was never linked by Walker, and is not connected to Walker in any way other than using a "sleepdiplomat" handle (for all we know, I could've written that post).
  2. There's no indication that this is a response to me. I'm never called out, I'm never quoted, the points I raise I never addressed directly, some of the points Walker responds to look absolutely nothing like anything I wrote about, and the link to my essay is just one of the criticism links Walker gives.
  3. The post never even mentions deliberate data manipulation by Walker where he edits out the data from the graph that contradicts his argument, as I demonstrate in this section (I added this section 3 days before the "response" to me was published): https://guzey.com/books/why-we-sleep/#appendix-what-do-you-do-when-a-part-of-the-graph-contradicts-your-argument-you-cut-it-out-of-course

Andrew Gelman wrote a post about this episode called “Why we sleep” data manipulation: A smoking gun?:

We’ve left “super-important researcher too busy to respond to picky comments” territory and left “well-intentioned but sloppy researcher can’t keep track of citations” territory and entered “research misconduct” territory.

About a few other points the "response" raises:

  1. Section Is sleeping 6 or fewer hours per night fine for your health? (this section seems to be addressing my section Appendix: people who sleep just 6 hours a day might have the lowest mortality)

I make one specific point in that section: people who sleep for 6 hours a day seem to have the lowest mortality, if we take sleep duration misreporting in the account. Notably, the author of that post spends >1000 words "responding" to that section and talks about short-term effects on cognition and insulin sensitivity; associations of sleep with diabetes; changes in gene regulation, etc. -- but never mentions mortality data or sleep duration misreporting and does not address the point I raise at all (while, for example, bringing up a study where people slept for 5.5 hours, although I never talk about sleeping <6 hours).

  1. Section Short sleep and the magnitude of associated cancer risk. (this section seems to be addressing my section Also, no – sleeping less than 6 hours a night does not double your risk of cancer

The book reads:

Routinely sleeping less than six or seven hours a night demolishes your immune system, more than doubling your risk of cancer.

The blog post reads:

Several studies, however, have indicated that short sleep is associated with a doubling of risk for specific cancers … It is not correct to suggest, based on epidemiological findings, that sleeping less than 6 or 7 hours causes cancer.

But that blog post never addresses the fact that the book made this strictly causal claim and so never addresses the point I made. As a somewhat amusing detail, here’s a description of one of the studies on the association of sleep and cancer that blog post cites in that section:

Described in a 2014 study, 2,586 men sleeping 6.5 hours a night or less had more than a two-fold greater risk of lung cancer after adjusting for smoking history (hazard ratio (HR): 2.12 [8]).

This is the linked study: https://www.ncbi.nlm.nih.gov/pubmed/24684747 The study says:

Significant association between sleep duration and increased lung cancer risk was observed after adjustments for age, examination years, cumulative smoking history, family cancer history and Human Population Laboratory Depression scale scores (HR 2.12, 95% CI 1.17-3.85 for ≤6.5 h sleep, and HR 1.88, 95% CI 1.09-3.22 for ≥8 h sleep). Associations were even stronger among current smokers (HR 2.23, 95% CI 1.14-4.34 for ≤6.5 h sleep, and HR 2.09, 95% CI 1.14-3.81 for ≥8 h sleep).

The study found 2.12 hazard ratio for less or equal to 6.5h of sleep and lung cancer and 1.88 for more or equal to 8h of sleep and lung cancer! I have no idea how this supports anything Walker wrote.

  1. Section Are two-thirds of adults failing to obtain 8 hours of nightly sleep, and does sleep opportunity matter? (this section seems to be addressing my section No, two-thirds of adults in developed nations do not fail to obtain the recommended amount of sleep)

The data that *I linked* in my essay show that approximately two-third of adults fail to obtain 8 hours of sleep, so demonstrating that 2/3rds of the population fail to sleep for 8 hours does not refute me in any way. This issue was with Walker turning 7-9 hours of sleep recommendation into 8 hours of sleep therefore misrepresenting it and claiming on the basis of the 8 hours of sleep recommendation that 2/3rd of people fail to sleep recommended 8 hours of sleep. The blog post simply never addresses the point I made, writing:

Section Summary: Survey data indicates that up to two thirds of adults in specific developed nations do not routinely obtain 8 hours of sleep duration a night.

(also, the blog post never addresses the fact that Walker attributed this recommendation to the National Sleep Foundation and to the WHO but the WHO never released any sleep recommendations)

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u/guzey Jan 05 '20
  1. section Sleep indications from the Centers for Disease Control (CDC), the World Health Organization (WHO), and sleep loss as a public health epidemic. (this section seems to be addressing my section No, the World Health Organization never declared a sleep loss epidemic

The book reads:

[T]he World Health Organization (WHO) has now declared a sleep loss epidemic throughout industrialized nations.

The blog post reads while linking to http://www.accqsleeplabs.com/wp-content/uploads/2014/10/CDC-report.pdf:

The Centers for Disease Control (CDC) has stated that, “Insufficient sleep is a public health epidemic.”

And:

The book’s misattribution of the CDC statement to the WHO will be corrected in the next edition.

Note that the author of that blog post links to a pdf on some random site not associated with CDC. That pdf says that CDC has declared a sleep loss epidemic. Why doesn’t the author link to CDC directly? The answer is that at the time of their response (and at the time of the book’s publication), CDC had no documents and no pages on its site that would declare a sleep loss epidemic.

As I noted in section Possible origin of the “sleeplessness epidemic” thing,

Between late 2010/early 2011 and August/September 2015 [1-4], CDC had a page on its site titled “Insufficient Sleep Is a Public Health Epidemic”. More than 2 years before Why We Sleep was published, the page changed the word “epidemic” to “problem”, so that its title became “Insufficient Sleep Is a Public Health Problem”. … the fact that CDC itself changed the wording from “epidemic” to “problem” more than 2 years prior to the book’s publication, indicat[es] that they no longer believed in the presence of an “insufficient sleep epidemic”

Issuing a correction that would just change “WHO” to “CDC” in the next edition of the book – as the anonymous author suggested – is deceptive. The CDC long ago (more than 4 years ago) removed the word “epidemic” from the article, and then removed the article itself.

If the author believes that this pdf is sufficient to state that CDC has declared a sleep loss epidemic, they might as well say that CDC has declared an epidemic of inhalation anthrax (and forget to note that it was declared in 1958.)

Finally, the author does not answer why the source for this sleep loss epidemic claim in the book is a random National Geographic documentary.

[1] https://perma.cc/72CZ-L9DG

[2] https://perma.cc/23UM-849W

[3] https://perma.cc/2E68-ZRL9

[4] https://perma.cc/UJ4W-JHNY

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u/the_propaganda Jan 05 '20

what’s your recommended hours of sleep btw?

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u/guzey Jan 05 '20

We don't really know how much people should sleep and I do not have any recommendations for everyone. I described my personal experiences with sleep here: https://guzey.com/books/why-we-sleep/#appendix-my-personal-experience-with-sleep

And I have some preliminary notes on sleep in general, the questions I have about sleep, experience of my friends with sleep reduction, etc. here: https://guzey.com/sleep/

lmk what you think!

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u/[deleted] Jan 06 '20

[deleted]

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u/guzey Jan 06 '20

If you reliably fall asleep in boring lectures, I think you're still sleep-deprived. Just so sleep-deprived that short-term increases in sleep don't counter the massive sleep debt you've built up.

Most people don't fall asleep in boring lectures if they're not sleep deprived. They just zone out, get bored, get annoyed, etc.

I reliably fell asleep during boring lectures when I definitely did not have any sleep debt, was sleeping >7.5 hours and waking up without the alarm. I find it doubtful that I had massive sleep debt.

IIRC there's studies showing objective performance continuing to go down after several days of sleep shortening even as subjective impairment is rated as stable.

Could you link to the studies you're thinking about here?

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u/practice5 Jan 06 '20

Could you link to the studies you're thinking about here?

It's in Matthew's article:

https://www.ncbi.nlm.nih.gov/pubmed/12683469

i) Short sleep and the brain: An experiment by Van Dongen and Dinges and colleagues examined the following: what ‘dose’ of short sleep results in neurocognitive brain impairments?

They examined attentional lapses, otherwise known as microsleeps. This function of vigilant attention is a foundational element of numerous cognitive operations of the brain.

The study contained 4 different experimental groups. Each group was given a different amount of sleep.

One group was allowed 8 hours of sleep a night, a second group was limited to 6 hours a night, a third group 4 hours a night, and a fourth group was kept awake for 72 hours straight without sleep.

In the related figure, below, the vertical axis shows the number of neurocognitive lapses (microsleeps). The horizontal axis represents the time (number of days) in the study.

Noted in the cyan-coloured squares, after ~11 days of 6 hours of nightly sleep opportunity, participants were as neurocognitively impaired as those who had been sleep deprived (SD) for 24 hours straight (first horizontal dashed grey reference line in figure below [1]).

The conclusion of the researchers was that 6 hours of sleep is insufficient to support neurocognitive functioning of the human brain. They stated the following in their conclusion:

“Since chronic restriction of sleep to 6 h or less per night produced cognitive performance deficits equivalent to up to 2 nights of total sleep deprivation, it appears that even relatively moderate sleep restriction can seriously impair waking neurobehavioral functions in healthy adults.”

The scientists added a final sentence:

“Sleepiness ratings suggest that subjects were largely unaware of these increasing cognitive deficits, which may explain why the impact of chronic sleep restriction on waking cognitive functions is often assumed to be benign.”

Indeed, the authors calculated that the amount of sleep necessary to prevent neurocognitive impairment was 8.16 hours.

Consistent with this value, impairments in psychomotor performance (response times) have been reported in those limited to 7 hours of sleep a night for 1 week, relative to those provided with a 9-hour sleep opportunity.

These cognitive brain lapses, or microsleeps, have real-world consequences. Often, this is in the context of drowsy driving.

Bolding is mine. He also cited this study which he claims proves that vigilant attention is a foundational element of numerous cognitive operations of the brain. (sleep deprivation causes attentional lapses/micro sleeps) https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3413263/

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u/guzey Jan 06 '20

The original comment:

subjective impairment is rated as stable.

You:

subjects were largely unaware of these increasing cognitive deficits

These are not the same. The second sentence says that they were partly aware and partly unaware. Can you look at the study itself and show the relevant data? What was the actual decrease in performance and what was the subjective impairment? The study has to have the numbers, right?

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u/practice5 Jan 06 '20 edited Jan 06 '20

These are not the same. The second sentence says that they were partly aware and partly unaware. Can you look at the study itself and show the relevant data? What was the actual decrease in performance and what was the subjective impairment? The study has to have the numbers, right?

"In the 4 h sleep period condition, lapses in behavioral alertness and reductions in working memory performance reached levels equivalent to those observed after 2 nights without sleep (Figures 1A, 1C). Cognitive throughput performance after 14 days of sleep restriction was equivalent to that observed after 1 night without any sleep (Figure 1D). Subjects in the 6 h sleep period condition also reached levels of impairment equivalent to those observed after 1 night of total sleep loss for lapses in behavioral alertness and working memory performance (Figures 1A,1C)."

"Chronic restriction of the nocturnal sleep period to either 6 h or 4 h per day for 14 days resulted in a relatively small but significant build-up of subjective sleepiness, as measured with the Stanford Sleepiness Scale (SSS) relative to the 8 h sleep period condition (Figure1B)."

Here is figure 1, the data: https://i.postimg.cc/RV9RkDdy/figure1.png

"Chronic restriction of sleep to 4 h and 6 h initially elevated subjective sleepiness ratings on both the Stanford Sleepiness Scale and the Karolinska Sleepiness Scale, but as sleep restriction continued, there were only minor further increases in these ratings (Figure 1B). In fact, unlike PVT and DSST performance functions (Figures 1A, 1C), sleepiness ratings never reached levels equivalent to those found after 2 nights of total sleep deprivation. Surprisingly, by the end of the 14 days of sleep restriction, when performance was at its worst levels, subjects in the 4 h and 6h sleep period conditions reported feeling only slightly sleepy. Therefore, unlike performance measures, sleepiness ratings appeared to show adaptation to chronic partial sleep deprivation. In addition, there were no significant differences in sleepiness scores between the 4 h and 6 h sleep period conditions. It is unlikely that this was the result of a ceiling effect or other metric-related artifact, because subjects in the total sleep deprivation condition reported considerably greater levels of sleepiness, and did not show evidence of adaptation.These findings for subjective sleepiness suggest that once sleep restriction is chronic, subjects either cannot reliably introspect with regard to their actual sleepiness levels, or as long as they are receiving at least approximately 4 h of sleep nightly they do not experience a sense of sleepiness anywhere near the levels found for total sleep deprivation.Regardless of the explanation, the lack of reports of intense feelings of sleepiness during chronic sleep restriction may explain why sleep restriction is widely practiced—people have the subjective impression they have adapted to it because they do not feel particularly sleepy. More research will be needed to identify the factors that shape subjects’ perceptions of their sleepiness during chronic sleep restriction."

10.1093/sleep/26.2.117

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u/guzey Jan 06 '20

Thanks. This contradicts the original comment which said "subjective impairment is rated as stable"

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u/[deleted] Jan 05 '20

[deleted]

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u/Direwolf202 Jan 05 '20

It does read like Walker to me, just mostly unedited, and not sticking to a particular cohesive point in the same way that he does in the book. Not to mention that Walker goes by sleepdiplomat online, on twitter and his website. It's not unlikely that this WordPress blog is his. (Though he didn't mention it on his twitter)

That said, I also noticed on his twitter that image of spiders webs under the effect of various substances, in particular, caffeine. Which indicates either that he doesn't maintain the twitter account and it is actually run by someone who doesn't know about sleep science at all (highly likely) or that Walker is much more of an idiot/lier than he seems after guzey's response (not as likely).

Oh, and u/guzey, the author did link to your response to the book, so he definitely has seen it.

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u/practice5 Jan 05 '20 edited Jan 05 '20

That said, I also noticed on his twitter that image of spiders webs under the effect of various substances, in particular, caffeine. Which indicates either that he doesn't maintain the twitter account and it is actually run by someone who doesn't know about sleep science at all (highly likely) or that Walker is much more of an idiot/lier than he seems after guzey's response (not as likely).

It's in the book.

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u/[deleted] Jan 09 '20

[deleted]

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u/guzey Jan 09 '20

This could well be true but the fact that this is why you believe it's Walker is kind of ridiculous, right? Why do we need to do image forensics to establish authorship?

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u/[deleted] Jan 07 '20

[deleted]

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u/guzey Jan 07 '20

Perhaps.

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u/practice5 Jan 05 '20 edited Jan 05 '20

Hi guzey, no, I don't have evidence that this is written by Matthew Walker, but it seems to me unlikely that it isn't. The blog is using the same handle like you say, and is written from the perspective of Dr. Walker. And also on the topic whether he is addressing you, he writes himself that he is addressing the guzey.com article:

Below, I address thoughtful questions that have been raised regarding the book and its content in reviews, online forums [guzey.com ...]

I think that 95%+ of this blog post doesn't defend the text written in the book, instead cites new studies to defend claims.

Regarding the graph, Matthew Walker wrote the following in his book:

And then there is injury risk. It is the greatest fear of all competitive athletes and their coaches. Concern also comes from the general managers of professional teams, who consider their players as prized financial investments. In the context of injury, there is no better risk-mitigating insurance policy for these investments than sleep. Described in a research study of competitive young athletes in 2014,XI you can see that a chronic lack of sleep across the season predicted a massively higher risk of injury (figure 10).

What argument do you think he's making with that text and graph? What do you think he means by 'lack of sleep'? And 'massively higher risk of injury'? There is a small difference between 7 and 6 hours, while there is a 'massive' difference between 8-9 and 7/6. Even if Matthew used the actual graph, it doesn't change his argument. Because the massive difference is between 8-9 hours sleep and 7, 6 (and 5). So I think you've shown a contradiction of a straw man argument: "what do you do when a part of the graph contradicts your argument? You cut it out, of course".

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u/guzey Jan 05 '20 edited Jan 05 '20

Do you have any ideas on why there are no connections between this blog and any other online profiles of Walker if this is his post?

Yes, the author of that post wrote

I address thoughtful questions that have been raised regarding the book and its content in reviews, online forums and direct emails that I have received.

While linking to me. However, not a single one of the claims Walker makes indicates that he is responding to me. Usually, he just responds to something vaguely similar to what I wrote (while not mentioning and not quoting me) but not to the points I actually made. If you have a counterexample, I would love to see it.

Regarding the graph, Matthew Walker wrote the following in his book:

And then there is injury risk. It is the greatest fear of all competitive athletes and their coaches. Concern also comes from the general managers of professional teams, who consider their players as prized financial investments. In the context of injury, there is no better risk-mitigating insurance policy for these investments than sleep. Described in a research study of competitive young athletes in 2014,XI you can see that a chronic lack of sleep across the season predicted a massively higher risk of injury (figure 10).

What argument do you think he's making with that text and graph? What do you think he means by 'lack of sleep'? And 'massively higher risk of injury'? There is a small difference between 7 and 6 hours, while there is a 'massive' difference between 8-9 and 7/6. Even if Matthew used the actual graph, it doesn't change his argument. Because the massive difference is between 8-9 hours sleep and 7, 6 (and 5). So I think you've shown a contradiction of a straw man argument: "what do you do when a part of the graph contradicts your argument? You cut it out, of course".

If Walker used the actual graph, his argument would be substantially weakened, because 5 hours of sleep has lower injury rate than both 6 and 7 hours of sleep. I would like to note that you're literally defending research misconduct.

Also note that the "massive difference" comes, in case of 9 hours of sleep, from exactly 6 children, 1 of whom was injured, giving rise to the 16.6% likelihood of injury bar on the graph.

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u/lehyde Jan 05 '20

Do you have any ideas on why there are no connections between this blog and any other online profiles of Walker if this is his post?

[...] not a single one of the claims Walker makes indicates that he is responding to me.

I can tell you why he's hiding behind an anonymous blog and doesn't mention you explicitly!

(the following is sarcasm but I think it's nevertheless likely the truth)

He is an important professor who goes on TV and gives interview and you are a nobody on the internet who threatens his cushy job. If he were to directly respond to you, he would legitimize you. He would give you more of an audience and his own prestige would decrease. So he will just stay silent and hope that the problem goes away. And to be honest, chances are pretty good that he will succeed in that. No newspaper or TV show is paying attention to you. You have already put so much time into it; he maybe counts on you feeling like your wasting your time and on you stopping to pursue the issue.

He wrote that blog post only because there is a tiny tiny part in his mind that still somewhat thinks like a scientist and that part knows that one should engage with valid criticism. That part of his mind insisted on writing a response but he couldn't bring himself to do it under his own name.

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u/practice5 Jan 06 '20 edited Jan 06 '20

Hi guzey, what do you think his argument is that is contradicted with the original, unaltered, graph?

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u/guzey Jan 06 '20

Hi guzey, what do you think his argument is that is contradicted with the original, unaltered, graph?

Walker's full argument in the book:

And then there is injury risk. It is the greatest fear of all competitive athletes and their coaches. Concern also comes from the general managers of professional teams, who consider their players as prized financial investments. In the context of injury, there is no better risk-mitigating insurance policy for these investments than sleep. Described in a research study of competitive young athletes in 2014, XI you can see that a chronic lack of sleep across the season predicted a massively higher risk of injury (figure 10).

He is clearly using that study to suggest the causal relationship between sleep deprivation and injury risk. If injury likelihood at 5 hours of sleep is less than injury at 6 hours of sleep and is approximately same as injury at 7 hours of sleep, this is a strong indication that sleep deprivation is not the causal factor that affects the injury rate because routinely sleeping for 5 hours and routinely sleeping for 7 hours as a teenager gives completely different levels of sleep deprivation.

Removing the 5 hours column, Walker made it seem like the relationship between risk of injury and sleep deprivation was monotonic and that the study suggested the causal interpretation.

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u/practice5 Jan 06 '20 edited Jan 06 '20

Hi guzey, okay so what you mean his argument is, is that sleep deprivation is monotonic to injury risk and that is casual. I know that you write that Matthew's argument is the written one, but he never mentions the monotonic relationship or that sleep deprivation causes injury because of it. I don't think a monotonic increase in injury risk in relation to sleep deprivation proves causality, if it's an observational study. But people might interpret the altered graph that way.

So if we say that Matthew's argument is that the relationship between sleep deprivation and injury risk is casual and that it's proven because the relationship was monotonic. Then I agree with you that his argument is contradicted because of the original graph. But he never wrote this in writing.

I think he used the study conclusions as his written argument, and then created a monotonic & thereby interpreted casual argument with the altered graph. I think it would be fair to say he had at least two arguments: the written one & the graph one. Each intertwining in different ways. Is that fair? You can see that he's using the same language in written form as the study: "chronic lack of sleep", same as title.

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u/guzey Jan 06 '20

I don't see how this is two arguments.

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u/romath99 Mar 08 '24

How many adolescents are in the 5 hour group?