Researchers identify sleep as a reason why personality traits predict longevity
I understand this is correlation not causation, but we have tons and tons of evidence for the negative effects of sleep deprivation.<p>Color me highly skeptical that there are negative effects associated with sleeping 8.5+ hours, up to say, 11 hours. Beyond 11 hours of sleep, I can see an argument being made for physical morbidity from lack of movement etc. But 8-9 hours of sleep nightly - my guess would be that people who get only 7 hours of sleep tend to be more successful, have jobs and families, and access to health care.  Whereas those sleeping 10 hours a night are less likely to have the income to get health care when necessary.<p>In other words, I'd be interested to see studies which test the hypothesis that sleep deprivation has a causal effect on morbidity, while excessive sleep only has a correlation.