system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5:Why do humans have to sleep?

I get the whole "recharging" idea but it isn't like our body is shutting down when we sleep, it is still using our body. So why do we have to sleep?
gpt
We don't know for sure! The best answer (ELI5 answer, not technical one) seems to be that it helps us remove some of the garbage that the cells in our brains produce throughout the day, and flush them out of the system. Though sleep certainly allows for a number of useful biological and neurological things to happen beyond that, and it's not entirely clear what the most important benefit of sleep is.