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Pablo_Stafforini comments on Open thread, August 4 - 10, 2014 - Less Wrong Discussion

5 Post author: polymathwannabe 04 August 2014 12:20PM

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Comment author: Pablo_Stafforini 04 August 2014 05:33:43PM *  2 points [-]

Another piece of potentially useful information that may be new to some folks here: sleeping more ~7.5 hours is associated to a higher mortality risk (and the risk is comparable to sleeping less than ~5 hours).

Relevant literature reviews:

Cappuccio FP, D'Elia L, Strazzullo P, et al. Sleep duration and all-cause mortality: a systematic review and meta-analysis of prospective studies. Sleep 2010;33(5):585-592.

Background: Increasing evidence suggests an association between both short and long duration of habitual sleep with adverse health outcomes. Objectives: To assess whether the population longitudinal evidence supports the presence of a relationship between duration of sleep and all-cause mortality, to investigate both short and long sleep duration and to obtain an estimate of the risk. Methods: We performed a systematic search of publications using MEDLINE (1966-2009), EMBASE (from 1980), the Cochrane Library, and manual searches without language restrictions. We included studies if they were prospective, had follow-up >3 years, had duration of sleep at baseline, and all-cause mortality prospectively. We extracted relative risks (RR) and 95% confidence intervals (CI) and pooled them using a random effect model. We carried out sensitivity analyses and assessed heterogeneity and publication bias. Results: Overall, the 16 studies analyzed provided 27 independent cohort samples. They included 1,382,999 male and female participants (follow-up range 4 to 25 years), and 112,566 deaths. Sleep duration was assessed by questionnaire and outcome through death certification. In the pooled analysis, short duration of sleep was associated with a greater risk of death (RR: 1.12; 95% CI 1.06 to 1.18; P < 0. 01) with no evidence of publication bias (P = 0.74) but heterogeneity between studies (P = 0.02). Long duration of sleep was also associated with a greater risk of death (1.30; [1.22 to 1.38]; P < 0.0001) with no evidence of publication bias (P = 0.18) but significant heterogeneity between studies (P < 0.0001). Conclusion: Both short and long duration of sleep are significant predictors of death in prospective population studies.

Grandner MA, Hale L, Moore M, et al . Mortality associated with short sleep duration: the evidence, the possible mechanisms, and the future. Sleep Med Rev 2010;14(3):191-203.

This review of the scientific literature examines the widely observed relationship between sleep duration and mortality. As early as 1964, data have shown that 7-h sleepers experience the lowest risks for all-cause mortality, whereas those at the shortest and longest sleep durations have significantly higher mortality risks. Numerous follow-up studies from around the world (e.g., Japan, Israel, Sweden, Finland, the United Kingdom) show similar relationships. We discuss possible mechanisms, including cardiovascular disease, obesity, physiologic stress, immunity, and socioeconomic status. We put forth a social–ecological framework to explore five possible pathways for the relationship between sleep duration and mortality, and we conclude with a four-point agenda for future research.

Grandner MA, Drummond SP. Who are the long sleepers? Towards an understanding of the mortality relationship. Sleep Med Rev. Oct 2007;11(5):341–60.

While much is known about the negative health implications of insufficient sleep, relatively little is known about risks associated with excessive sleep. However, epidemiological studies have repeatedly found a mortality risk associated with reported habitual long sleep. This paper will summarize and describe the numerous studies demonstrating increased mortality risk associated with long sleep. Although these studies establish a mortality link, they do not sufficiently explain why such a relationship might occur. Possible mechanisms for this relationship will be proposed and described, including (1) sleep fragmentation, (2) fatigue, (3) immune function, (4) photoperiodic abnormalities, (5) lack of challenge, (6) depression, or (7) underlying disease process such as (a) sleep apnea, (b) heart disease, or (c) failing health. Following this, we will take a step back and carefully consider all of the historical and current literature regarding long sleep, to determine whether the scientific evidence supports these proposed mechanisms and ascertain what future research directions may clarify or test these hypotheses regarding the relationship between long sleep and mortality.

Comment author: gwern 04 August 2014 07:09:31PM *  10 points [-]

I don't find these results to be of much value. There's a long history of various sleep-duration correlations turning out to be confounds from various diseases and conditions (as your quote discusses), so there's more than usual reason to minimize the possibility of causation, and if you do that, why would anyone care about the results? I don't think a predictive relationship is much good for say retirement planning or diagnosing your health from your measured sleep. And on the other hand, there's plenty of experimental studies on sleep deprivation, chronic or acute, affecting mental and physical health, which overrides these extremely dubious correlates. It's not a fair fight.

Comment author: Pablo_Stafforini 04 August 2014 07:27:02PM *  1 point [-]

Yes, my primary reason for posting these studies was actually to elicit a discussion about the kinds of conclusions we may or may not be entitled to draw from them (though I failed to make this clear in my original comment). I would like to have a better epistemic framework for drawing inferences from correlational studies, and it is unclear to me whether the sheer (apparent) poor track-record of correlational studies when assessed in light of subsequent experiments is enough to dismiss them altogether as sources of evidence for causal hypotheses. And if we do accept that sometimes correlational studies are evidentially causally relevant, can we identify an explicit set of conditions that need to obtain for that to be the case, or are these grounds so elusive that we can only rely on subjective judgment and intuition?

Comment author: ChristianKl 04 August 2014 10:04:11PM 0 points [-]

Based on that data, I think a blanket suggestion that everybody should sleep 8 hours isn't warranted. It seems that some people with illnesses or who are exposed to other stressors need 8 hours.

I would advocate that everybody sleeps enough to be fully rested instead of trying to sleep a specific number of hours that some authority considers to be right for the average person.

I think the same goes for daily water consumption. Optimize values like that in a way that makes you feel good on a daily basis instead of targeting a value that seems to be optimal for the average person.

Comment author: Pablo_Stafforini 04 August 2014 10:14:57PM *  0 points [-]

What are your grounds for making this recommendation? The parallel suggestion that everyone should eat enough to feel fully satisfied doesn't seem like a recipe for optimal health, so why think things should be different with sleep? Indeed, the analogy between food and sleep is drawn explicitly in one of the papers I cited, and it seems that a "wisdom of nature" heuristic (due to "changed tradeoffs"; see Bostrom & Sandberg, sect. 2) might support a policy of moderation in both food and sleep. Although this is all admittedly very speculative.

Comment author: ChristianKl 04 August 2014 10:42:02PM 1 point [-]

What are your grounds for making this recommendation?

Years of thinking about the issue that aren't easily compressed.

In general alarm clocks don't seem to be healthy devices. The idea of habitually breaking sleep at a random point of the sleep circle doesn't seem good.

Let's say we look at a person who needs 8 hours of sleep to feel fully rested. The person has health issue X. When we solve X than they only need 7 hours of sleep. The obvious way isn't to wake up the person after 7 hours of sleep but to actually fix X.

That idea of sleep seems to both reflect the research that forcibly cutting peoples sleep in a way that leads to sleep deprivation is bad. It also explains why the people who sleep 8 hours on average die earlier than the people who sleep 7 hours.

If I get a cold my body needs additional sleep during that time. I have a hard time imagine that cutting that sleep needs away is healthy.

If we look at eating I also think similar things are true. There not much evidence that forced dieting is healthy. Fixing underlying issues seems to be preferable over forcibly limiting food consumption.

While we are at the topic of sleep and mortality it's worth pointing out that sleeping pills are very harmful to health.

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