system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: When and why did 8 hours of sleep become the standard for a solid night’s rest?
gpt
It is thought that we originally slept in 4 hour increments, and obviously always had to have people tending to a fire for the majority of our existence(Society and everything is relatively recent). 

I would think 8 hours of sleep came around the time of post-industrialization, and that it really hasn't been standardized till recently. 

For some people 8 hours is also too much, it really isn't a standard, just a guarantee that you'll get enough.

As you age you actually need less sleep.