Why do we sleep?

[DeimosSaturn]

THere are people who have perfect recall of everything or photographic memory who require the same amount of sleep as a regular person. There are people who only require 1 hour of sleep per 24 hours and are highly productive, and there are people who sleep 10 hours a day with horrible memory. I think sleep deprivation just makes it difficult to remember things simply because the person/animal is fatigued and focus to form memories requires effort. It's very likely sleep has almost no really necessary function biologically or cognitively from existing studies and evidence. Plenty of animal species do not sleep at all. This evidence is very flimsy.

[THESocialJusticeWarrior]

Wrong. We will die without sleep and nothing in this video explains that. You didn't do your homework. Try again.

[wwickeddogg]

So if you don't sleep you should remember what you learned better. The lesson here is too sleep a lot on days before you learn new things, but to never sleep the night before a test.

[sooooooooDark]

then why do cats sleep so much (like 18h/day) and humans like 8 or so?