Sleep is an important physiological process in metabolic activities. Without sleep, there is no health, lack of sleep, not only the body consumption can not be supplemented, but also the lack of hormone synthesis will cause imbalance in the body environment. After a series of studies on sleep and human immunity, American immunologists believe that sleep can not only eliminate fatigue, but also has a close relationship with improving immunity and resisting diseases. The number of T lymphocytes and B lymphocytes in the blood of people who get enough sleep is obviously increased, and these two kinds of cells are the main force of human immunity. Sleepiness is a sign of mental fatigue. You shouldn't wait until then to go to bed. Only by developing the habit of regular sleep and ensuring that the sleep time is not less than 7 hours a day can we maintain the normal operation of the biological clock in the sleep center. Therefore, young people should also learn to control their living habits and prevent their natural rhythm from being disrupted and falling into a vicious circle.