1 Infants require about 14-15 hours a day. 2  Teenagers need about 8.5-9.5 hours on average. 3  Most adults need 7 to 9 hours a night for the best amount of sleep, although some people may need as few as 6 hours or as many as 10 hours of sleep each day.etting a good night's sleep is good for your body and your mind. See how many of these items you can check off in the next 30 days. You're on your way to better sleep! Take this WebMD quiz and test your knowledge of sleep – getting it, losing it, and how to do it better.