More than 1/3 of a person’s life is spent in sleep, and the right amount of sleep time is needed every day, otherwise, people are prone to physical or psychological diseases, which shows how important sleep is for people to come. Sleep is also the most important and cyclical physiological process in a limited life. Why is sleep so important for life? The following is an introduction to the importance of sleep in terms of its characteristics and functions. The occurrence and regulation of sleep is one of the unique functions of the brain and involves changes in all aspects of the body. In general, sleep is a periodic physiological process consisting of two sleep states: non-rapid eye movement (NREM) and rapid eye movement (REM). The muscles are not loose enough, and the eyes do not move quickly. A normal adult sleep first into NREM sleep, sleep from light to deep, and then into REM sleep insomnia is a fairly common civilization disease. In 1991, someone surveyed 36% of Americans complaining of insomnia in the past year, of which 27% were suffering from transient insomnia and 9% were suffering from chronic insomnia, so the prevalence and severity of insomnia is evident. Sleep, REM sleep ends (about 90 minutes), and then goes into NREM sleep, and then into REM sleep, and there can be 3-6 NREM/REM sleep cycles for a full night of normal sleep. At the same time, with the change of sleep cycle, human breathing, heart rate, blood pressure, body temperature, muscle tone, etc. also undergo periodic changes and adjustments, with the physiological needs to adapt to the human body at rest and organism recovery. Therefore, it can also be said that sleep is a physiological process of self-regulation of the human body. After observational studies, generally speaking, sleep may have six functions: (1) Promote the development and development of brain functions. It is mainly related to REM sleep, during which the brain is still active and the brain nerve function is still in the process of constantly integrating various information from memory and constantly adjusting the connections between the brain nervous system. (2) Preservation of energy in the brain and the body. NREM sleep is a relatively quiet stage of brain and body functions, when the whole body metabolism decreases a lot, especially during deep sleep, pulse rate slows down, dropping 10-30 times per minute, breathing becomes deeper and slower, basal metabolic rate and brain metabolism decreases 10-15%, blood pressure decreases 10-30 mmHg, cerebral blood flow decreases 25%, and the brain nutrient content increases significantly. Therefore, sleep both preserves the brain’s energy and restores the function of the torso. (3) It consolidates memory and ensures optimal brain function. Sleep deprivation or sleep deprivation can cause a person’s attention and memory to decline, and what has been remembered is easily forgotten. For example, the very car accident, the U.S. space shuttle Challenger tragedy and the Three Mile Island nuclear power plant accident were all related to the lack of sleep and the lack of timely response by the personnel involved. (4) Enhance the body’s immune mechanism. During sleep, the organism can regulate the production of more cells and substances with immunity, which is beneficial for the body to fight against diseases; on the contrary, lack of sleep or sleep disorders can also cause immune dysfunction, leading to the occurrence and development of diseases. (5) Promote the growth of the body and slow down aging. The vast majority of growth hormone is produced during deep sleep, and growth hormone promotes the growth of the body and delay aging substances, so sleep can promote growth and delay aging, in fact, many long-term insomnia patients often appear premature aging, is also a verification. (6) Protection of the central nervous system. During sleep, there is a weakened permeability of the blood-brain barrier, thus preventing harmful substances from entering the brain and playing the role of protecting the central nervous system.