[f38zf5vdt]

Indeed, it's called the glymphatic system. We evolved to have a circadian system that drains brain waste products during sleep. There are probably other unknown neurological consequences of sleep that remain to be detailed.

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

https://www.nature.com/articles/s41467-020-18115-2

[bmitc]

It's not just us, as in humans. (Not saying you said otherwise.) Practically all animals sleep, even invertebrates like octopuses.

[misja111]

Even spiders do: https://www.cbsnews.com/news/spiders-may-sleep-and-dream-lik....