Why do so many organisms, like mammals, need sleep to a degree that it makes it a requirement to live like food and water, while other organisms don’t sleep at all?

Question

Sleep does a lot of things here and there, but has there been a thesis pin pointing the exact thing that absolutley requires sleep? Could it be that the brain, even the ones not as evolved as the human ones, can not go on for long without rest due to their bio-chemistry or something like that? Very primitive “brains” like insects and so on don’t require so much brain power like more complex organisms, maybe?

In: Biology

Answer 1

Every animal with an actual brain sleeps to some degree. Some, like sharks, are able to sleep with one half of their brain at a time, allowing the other half to remain active while the other rests.

Once you get to animals like an insect – there is no “brain” to speak of – it’s just a little web of neurons that reacts to stimuli but there’s no central processing center – therefore nothing to go to sleep.