From my reading, the research only looks at monophasic sleeping patterns and so gives no real useful information on the effects of polyphasic sleep on health.
Agreed in principle, but in practice I think the argument goes as follows:
1) There is evidence that prolonged lack of sleep (6h/night or less) leads to an early death
2) Many polyphasic sleep methods involve dramatically less sleep than 6h a night
3) There is no implied correlation between those two statements, but a cautious person who wants to maximise their chance of living as long as possible would infer that:
- Given the lack of data, it is probably a better idea to avoid polyphasic sleep altogether until proper studies are conducted.
Previously, the argument was that there is no evidence linking lack of sleep with death, therefore why not give polyphasic sleep a go. I think that argument is not valid anymore.
Read my comment more carefully. I didn't say there's conclusive evidence of a link - just that a cautious individual who wants to maximise their lifespan will probably assume that it's best to sleep 6-8 hours a night.
Edit: Of course, that's assuming the study results are actually correct, which according to ajkirwin's comments, they're possibly not.
Polyphasic sleep is based in maximizing the amount of time sleeping in REM cycles, which is supposed to be the phase of sleep when the benefits of sleeping are higher.
Monophasic sleep deprivation doesn't have as many cycles of REM sleep as polyphasic sleep, given equals amounts of time slept.
To compare monophasic and polyphasic a study should include both types of sleepers.
Perhaps such study could find a proper pool of candidates in forums like
Having read the article and the abstract of the paper in question, it seems a little.. off. For a start, it's a meta-analysis pulling from a simply massive pool. And it asks people about areas of their life from a few years upto two and a half decades.
Do YOU know how often you slept under six hours a night in the last year? 2 years? 5? 10?
Did all these people keep detailed sleep diaries every single night?
This just raises too many questions. Meta-analysis is most useful when restricted to much smaller sample sizes where a greater amount of data can be obtained and analyzed.
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Edit for More Info:
It seems that this paper is a meta-study of OTHER papers. And that 80% of the data used came from a single study by Daniel F. Kripke of UCSD.
The conclusions of Kripke study, which were meta-analysed, were notably different than Cappuccio's, namely:
"The best survival rates were found among those who slept 7 hours per night. The study showed that a group sleeping 8 hours were 12 percent more likely to die within the six-year period than those sleeping 7 hours, other factors being equal. Even those with as little as 5 hours sleep lived longer than participants with 8 hours or more per night."
