9-11 hours at ages of born-11. 8-10 hours at ages of 11-13 id say. 7-9 hours for teenagers and until age like 45. (8 is perfect) 8-10 for the rest. Naps must be of 15 minutes-40 minutes tops. Too much sleep can cause one to be slow, get used to sleeping *addiction lol*. Too little sleep makes one weak and tired.
The human body need's about 8 hours to recover all the energy it lost During those 12-24 hours in movement. It depends on how many hours you were awake. but generally is 8 hours, if the human body sleeps more than what it move's it will loose its potential and will become weak and heavy to move, so sleeping too much it's bad too.
as a teenage we need more sleep.research shows teenage's are suppose to get 12 WHOLE HOURS EVERY NITE!...which probably doesn't happen to many of us because we are so busy.research also shows people how don't sleep gain weight.hope this helps:)