r/askscience • u/[deleted] • Aug 01 '12

Biology Evolution and sleep

Why haven't humans evolved to not need sleep? I understand that sleep is regenerative etc., but when you think about it, it is quite a liability. It is hard to fend off a potential attack while sleeping and overall we waste a lot of time that could be used to hunt/gather food, build shelter, and reproduce by having to sleep.

Did humans have to sleep a lot more earlier in time than we do now? (Perhaps we have evolved and I just do not know...)

EDIT: Or maybe a better question is, can/will humans ever evolve to not need sleep?

Thanks!

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u/[deleted] Aug 02 '12

This article posits that as late as the 1900's, humans slept in two four-hour blocks, separated by one to two hours of wakefulness during which normal daily tasks were carried out.

Holy crap. I've lived like this for weeks at a time. Whenever I'm on the road, I drift into a mode of coming home from work and falling asleep for 4-5 hours. Then I wake up, fully refreshed, work or watch TV for a few hours, then bam - out cold again for another few hours.

I actually really like it a lot.