(1) Eliminate fatigue and restore energy: Sleep is the main way to eliminate physical fatigue. Because during sleep the gastrointestinal tract functions and its related organs, synthesize and manufacture energy substances for the body for use during activity. In addition, the body temperature, heart rate and blood pressure drop, and the respiration and some endocrine secretion decrease, so that the basal metabolic rate decreases and thus the physical strength is restored. (2) Protect the brain and restore energy: those who do not get enough sleep show irritability, agitation or depression, inattention, memory loss, etc.; long-term lack of sleep can lead to hallucinations. Those who get enough sleep have more energy, quick thinking and high efficiency. This is due to the fact that the brain in the sleep state oxygen consumption is greatly reduced, which is conducive to brain cell energy storage. Therefore, sleep is good for protecting the brain and improving brain power. (3) Enhance immunity, rehabilitation of the body: the human body under normal circumstances, can produce antibodies to various invasive antigenic substances, and through the immune response and remove them to protect human health. Sleep can enhance the body’s ability to produce antibodies, thus strengthening the body’s resistance; at the same time, sleep can also accelerate the self-rehabilitation of various tissues and organs. In modern medicine, sleep is often used as a therapeutic tool to help patients get through the most painful period, so as to facilitate the recovery of diseases. (4) Promote growth and development: sleep is closely related to children’s growth and development, infants and children continue to develop their brains for a long time after birth, and this process cannot be separated from sleep; and children’s growth is accelerated in the sleep state, because plasma growth hormone can be maintained at a high level for several hours during sleep. Therefore, children should be guaranteed sufficient sleep to ensure their growth and development. (5) Delay aging and promote longevity: In recent years, many research studies have shown that healthy and long-lived elderly people have a good and normal sleep. Human life is like a burning flame, and regular combustion is life lasting; if the high and low combustion will shorten the time, so that people die early. Sleep time is just like the minimum degree of flame burning, so it can slow down aging and ensure the long life. (6) Protection of human mental health: Sleep is important for the protection of human mental health and maintenance of normal mental activities. Because a short period of poor sleep can lead to inattentiveness, while a long period of time can cause abnormalities such as irrational thinking. (7) Beneficial to skin beauty: During sleep, the circulation of skin capillaries increases, and its secretion and removal process is strengthened, which accelerates the regeneration of skin, so sleep is beneficial to skin beauty.