Generally adults can maintain a sleep time of about 8 hours, but there is no mandatory requirement for daily sleep time, which is generally based on their own situation. As long as you are in good spirits the next day, you are getting enough sleep, which can depend on your own needs. The amount of sleep needed varies by age group. Generally newborns sleep around 18 hours; infants around 12 hours; preschoolers around 10 hours; teenagers 8-9 hours; adults 7-8 hours; and the elderly may reduce their sleep time to around 6 hours because of various declining functions. People with sleep disorders can drink a glass of hot milk before going to bed and perform appropriate physical exercise during the day to assist in falling asleep, improve the quality of sleep and ensure that the brain is fully rested. After sufficient sleep, nerve cells and memory cells, etc. are likely to play their best role. If you do not have enough sleep and poor sleep quality for a long time, it will easily lead to various health problems, such as mental weakness, sleepiness, malnutrition, etc. Therefore, in order to ensure good health and to maintain high efficiency in daily work and study, sufficient sleep should be guaranteed.