Answer:
It depends on who you are talking about.
Explanation:
For children, studies have shown that they need 9-12 hours of sleep each night. Assuming they get up at 7:00 am in the morning, they should be in bed by no later than 10:00 pm. For adults, they can sleep less than children, therefore making them able to stay up later, and get up earlier. I would say, everyone should have a minimum of 7 hours to sleep, otherwise you get cranky because you're immune system doesn't have enough rest.
Hope this helped.
Also, DON'T copy this word to word. You're teacher see EVERYTHING >.< (it's creepy)
