system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: 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?



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?
gpt
No-one really knows for sure why we sleep, but it’s not just mammals that sleep. The most compelling theory that I’ve heard is that sleep is when your brain is able to get rid of waste products that build up during your waking hours, however most organisms, including those that don’t have brains, have some kind of day-night cycle where they’re dormant for a period of time.