How much sleep is appropriate is related to age and individual differences, and the average adult needs 7-8 hours of sleep per day. There are differences in the length of sleep for people of different ages. In addition, individuals have different physical and mental states, and have different requirements for sleep. Generally, sleep duration decreases with age. Newborns may need nearly 20 hours of sleep a day, and as they grow into adolescents, their sleep time usually shortens to about 9 hours. Medically, it is considered appropriate for adults to get 7-8 hours of sleep per day, when they can fit in a day of work and study. Elderly people sleep about 6-7 hours a day. The specific sleep time is based on the ability to wake up refreshed and energized. It is recommended that in daily life regular routine, to ensure adequate sleep, avoid playing electronic products for a long time, stay up late to hurt the body.