> There's no dispute there are deleterious effects of sleep deprivation and accruing sleep debt, and that people would be better off with a full 8 hours of sle

> There's no dispute there are deleterious effects of sleep deprivation and accruing sleep debt, and that people would be better off with a full 8 hours of sleep. I question this, given that modern hunter gatherers only get about 6.5-7.0 (quality) hours of sleep. Probably, most of us in the modern world have poor quality sleep, and this confounds epidemiological studies by creating the illusion that we need long duration of sleep. There's also genetic variability in sleep duration needs. A small number of people are legitimately fine on 4-5 hours. > also produce the same finding amongst people averaging over 9 hours a night. Again, confounds. Depressed people, unemployed people, etc. The problems with empirical sleep research are largely methodological problems that all of epidemiology faces.