Why do we need sleep and what happens without it?

[physics user1]

Why do we need to sleep, why we have allucination, feel bad and die if we don't?
What happens in our brain and what makes sleeping so special and Important?

Will we be able to develop some chemicals or something that allows us to stay awake without troubles or problems some day and avoiding the need to sleep for ever?

 

[jedishrfu]

This wikipedia article answers many of your questions:

https://en.wikipedia.org/wiki/Sleep

During sleep the brain reorganizes itself, filing away important facts and events for future use.

The most recent explanation for sleep is that the brain sheds interstitial waste products (see Increased waste clearance of brain topic):

A publication by L. Xie and colleagues in 2013 explored the efficiency of the glymphatic system during sleep and provided the first direct evidence that the clearance of interstitial waste products increases during the resting state. ... On the basis of these findings, they hypothesized that the restorative properties of sleep may be linked to increased glymphatic clearance of metabolic waste products produced by neural activity in the awake brain.
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