Eli5 Why do we need around 8 hours of sleep?

Question

I get why we need to sleep and all that. But why specifically 8 hours? Why not 4 or 13 or any other random number of hours?

In: 0

Answer 1

The number of hours does vary by age, as you can see [from this article](https://www.cdc.gov/sleep/about_sleep/how_much_sleep.html), and as far as why specifically 8 hours, we typically sleep at night, so that likely has something to do with it.