How many hours of sleep is considered fully restorative?

8-8.4 hours in adults, the sleep of 8-8.4 hours is considered fully restorative. In some cultures, total sleep is often divided into an overnight sleep period of 6-7 hours and a nap of 1-2 hours. some people may need as little as 5 hours or as much as 10 hours of sleep every day. the period of time a person sleeps depends also on the fact whether he or she has been deprived of sleep in previous days. sleeping too little creates a sleep debt. this debt needs to be adjusted by sleeping for longer periods over the next few days. people who sleep less have an impairment of judgment and reaction time