A question to lose sleep over

You sleep because, either,1) It's evolutionarily chosen as a resource saver. 1/3 of the day we're inactive, so we don't use up resources. Can't see well at night, anyway. If this is true, we don't sleep because we "need" to, we sleep because it was selected for as a resource conservation measure.or2) We're doing "maintenance" of some sort, cognitive or physical. If this is true, lack of sleep should hurt us in some way.Or both.The answer is, in fact, not very clear.Despite the nearly universal idea that lack of sleep is harmful, it's shockingly difficult to "prove" it has harmful effects other than to make us really sleepy. First, in our daily lives, lack of sleep is associated with stress, which itself causes many problems. Second, in animal studies it's nearly impossible to keep animals from sleeping without stressful, anxiety producing measures - so many of the ill effects of sleep deprivation in these studies is also attributable to stress.REM sleep - associated with dreaming - seems a likely candidate for some sort of special "maintenance" task. Many people believe that memory consolidation occurs during REM sleep, and there's evidence to show that...yet many anti depressant drugs reduce or completely eliminate REM sleep, with no detectable effect on learning or memory.The reason you've never had a satisfying answer: There are no satisfying answers. Fascinating area of study, astonishingly resistant to giving up its secrets.

Hmmmm...Hard to say. The drugs have pretty wide-ranging effects, so pinning it on the REM sleep is going to be pretty difficult.It's interesting because many studies suggest that REM sleep deprivation has huge, dramatic effects on health and memory, yet these folks seem - more or less - fine. Certainly nothing on the order of what you would predict. Maybe the drugs "take the place" of REM sleep? That's just a WAG on my part.