http://www.iflscience.com/health-and-medicine/why-do-we-sleep
maybe you should ask Thomas Edison
not sure how this ties in with evolution but i assume sleeping a lot was not ideal when needing food or trying to not get killed by lions
huh? all humans and animals by instinct create protective shelters to guard them from prey when sleeping if the lion finds your cave at night, you die mankind lives on — In Hell Week for Navy SEALs, they are exposed to a massive amount of sleep deprivation to the point where most people fall asleep if they aren’t moving too much. But, they take it to another level, they let people sit on the beach for a few hours and fire all sorts of high decibel weapons around them, but since none of them are moving that much, they all fall asleep and REM sleep starts quickly and assists in regaining lost sleep. But, if you can’t find food and haven’t slept and pass out from exhaustion - yeah that lion’s gonna kill you.
---- primitive weapons and methods were created thousands of years ago to get by.
if you want to know how people get by in the current times, I think Talib Kweli sums it up nicely in his song:
da fuq am i reading
Because we’re tired. That’s why.
^but why 8 hours
I guess it is better for us to shut down at night, rather than wander around in the dark and fall in a hole, or be eaten by panthers and Slender Man.