Three Essentials of Health Preservation, one of the masterpieces of TCM, said: "Sleeping peacefully is the happiest thing in life. In a person's life, about 1/3 of the time is spent on pillows. Sleep and health are "lifelong companions". Traditional Chinese medicine has always attached importance to the science of sleep, believing that "sleeping and eating are important tasks of health preservation" and "those who can sleep and eat can live forever". Health care during sleep is equally important. At night, people's blood circulation is slow; High blood viscosity; Slow metabolism affects the increase of cell activity secretion; The body's anti-stress ability is reduced; Insufficient energy for self-repair and adjustment; The blood volume is relatively insufficient, and the circulation is slow, which can not guarantee the blood supply and oxygen supply of important organs such as the heart and brain. The body's resistance and immunity are reduced. 70% of cardiovascular and cerebrovascular diseases occur at night.