Bad News for Slugabeds
I was a postdoctoral fellow at Argonne National Laboratory and had the pleasure of working with George Sacher. At the time, he was president of the Gerontological Society of America and had spent his life working on ways to increase lifespan. He was a proponent of hormesis, the idea that moderation was the path to a longer life. Of course, some things should be off the list, like a moderate amount of murder.
Don’t eat too much or too little, don’t drink too much or too little. Did you know that small doses of strychnine were used as a performance enhancer? I put sleep in this perspective — neither too much nor too little. The National Sleep Foundation agreed and recommended seven to nine hours of sleep per day for adults between 18 and 64 years of age.1
That’s why I was surprised when AASM released their recommendation on sleep time and said: “Since the panel could not reach consensus that longer sleep was physiologically harmful, and since there was a consensus that longer sleep is beneficial for some individuals (e.g., younger adults, those recovering from sleep loss), no upper limit of sleep duration was included in the recommendation statement. As more evidence is collected regarding long sleep, this recommendation may need to be revisited.”2 (p. 939) And yet the literature review prior to the statement was based on nearly 1,600 articles.
Dr. Chun Shing Kwok and colleagues from the University of Keele, United Kingdom, have recently published a dose-response meta-analysis. 3 Most of the researchers were cardiologists. It included 74 studies and 3,340,684 participants. The researchers looked at all-cause death, stroke and cardiovascular disease, using seven to eight hours as the recommended duration. They found no difference in mortality with self-reported sleep times less than seven hours, but significant increases in risk ratios for more than eight hours of sleep. The studies reviewed were similar (although I have to admit that I did not do a detailed comparison). How did these groups come to different conclusions?
The methodological difference between these two papers is clear: AASM used a “literature review” and consensus process, whereas the UK study used statistics. As I gear up for another semester of teaching statistics to undergraduates, you can probably guess which side I’ll be on. I’m all for consensus, and the RAND process formalizes the method for achieving consensus in a reasonably unbiased way. But consensus should be used only when there is insufficient data. I think the UK group provides an adequate amount of data and a meticulous analysis.
For years, the focus of sleep-related professional groups has been on insufficient sleep and associated medical complications. Part of this focus has been due to experimental evidence: When research subjects are deprived of sleep, there are behavioral and physiological consequences. Experimental control supports a cause-and-effect relationship. Experimental evidence of the negative consequences of extended sleep is lacking, because it is easier to keep people awake than to get them to sleep longer.
Nevertheless, the meta-analysis indicates that there is a statistically significant relationship between long sleep times and cardiovascular disease. Is sleeping longer causing heart disease? We can’t make a causal claim with the evidence available. At a minimum, patients with self-reported long sleep times should have further evaluation by physicians.
It seems to me that if we berate those who fail to get enough sleep by choice, we should also have a word or two for the slugabeds (lazy people who stay in bed late), which, by its very name and definition, is pretty negative. I’ve never met a slug I liked. I may get some harsh comments from slug fans for saying this. Bring it on.
Of course, I’ll reserve my negativity for those who voluntarily stay in bed dozing on and off and not those who have a long sleep need or are taking medications that cause excessive sleepiness. And, if anyone asks, I will say that it is better to sleep eight hours a night than more or less. Hormesis.
- https://sleepfoundation.org/press-release/national-sleep-foundation-recommends-new-sleep-times/page/0/1 (accessed 8/7/18)
- Watson NF, Badr MS, Belenky G, Bliwise DL, Buxton OM, Buysse D, Dinges DF, Gangwisch J, Grandner MA, Kushida C, Malhotra RK, Martin JL, Patel SR, Quan SF, Tasali E. Joint consensus statement of the American Academy of Sleep Medicine and Sleep Research Society on the recommended amount of sleep for a healthy adult: methodology and discussion. J Clin Sleep Med 2015;11(8):931–952.
- Kwok CS, Kontopantelis E, Kuligowski G, Gray M, Muhyaldeen A, Gale CP, Peat GM, Cleator J, Chew-Graham C, Loke YK, Mamas MA. Self-reported sleep duration and quality and cardiovascular disease and mortality: A dose-response meta-analysis. Journal of the American Heart Association 2018(7):e008552.