Why do we need sleep?

Don't get me wrong, I'm not saying that we DON'T need sleep. I just like to know the "why" on everything So I was just wondering "why" do we need sleep :D :?: ?

I think it's mainly for keeping us emotionally stable, and to keep the neurochemicals in our brain balanced. After a long long time without sleep, we have a tendency to die, but I don't know why.

think of your mind as a rechargable battery.
and when your awake your using energy.
when your asleep your recharging.
get the idea?

Like much about ourselves, we do not fully understand the exact reasons for why we sleep. We know certain hormones are created at higher levels during sleep; we know sleep aid in certain restoration processes, but even this is not so clear as most physiological needs can be met with merely rest, and signs of sleep depravation first show up in the brain not the body. So we do know some, but are still pretty far from fully understanding sleep, in my humble opinion.

To replenish the chem's in our brain, balance them out...and also to replenish our energy...to reserve it...its like were very good and efficient rechargable batteries..

To branch out into the chemical side of it...say for instance you get drunk one night, and you wake up the next day with a hangover...well their are a bunch of alien chemicals effecting your brain and your judgement, and effecting other chemicals...so thats why you wake up kinda sick feeling and stuff because your body is trying to recharge those chem's that were effected and get the bad ones out of your brain and blood. (your system)

To keep us out of trouble when the sun is down.

:D

I liked that Lowercase, best explaination I've heard.