Healthy sleep isn't just about getting enough sleep; getting the right kind counts, too. While you sleep your brain stays active, and it actually takes several stages of sleep to make you feel well and refreshed. Just how much sleep we need changes as we age, from 16 to 18 hours a day for newborns to 7 to 8 hours a night for adults. If you find yourself feeling tired or fatigued during the day even after a full night in bed, you may have a sleep disorder. See your family doctor or a sleep specialist for help.