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

I know the question sounds a bit silly, but for real: Is it a biochemical necessity? Wouldn't there also be an evolutionary advantage with being able to hunt 24/7? And, consequently, are there any species that do not sleep?

**Edit:** Thank you all for your input so far! Very intriguing, indeed, and certainly a hard nut for science to crack. I've Google-Scholar'ed around a bit and found publications from 1901 to 2005, all saying "while we don't know *why* we need to sleep..." - unfortunately all paywalled so I can't check them out more closely before I get back to work tomorrow...
gpt
Animal species with atypical sleep: whales and dophins can rest their brains one hemisphere at a time. Fishes can swim in their sleep. Common swifts can sleep in four-second intervals while in flight (studied by Emile Weitnauer).

Muscles must rest to restore ATP, brains need energy and oxygen, food needs to be digested… It makes sense to align these cycles and have one state where the entire body is resting, and another where it is entirely available.