The sleep-wake cycle is a common physiological rhythm in humans and higher animals, and in humans, sleep can take up to one-third of the time of life. The entire sleep process includes light sleep, deep sleep and rapid eye movement sleep. In adults, the time required for deep sleep varies greatly from person to person, accounting for about 15-25% of the total sleep time, but not the longer the better. The regulation of sleep and wake cycles is a physiological process involving the coordinated integration of multiple centers and systems, and the normal process includes the waking state and the sleeping state. The waking state is behaviorally characterized by a variety of changing motor activities and active thinking activities, and is very sensitive to environmental stimuli and can quickly make various adaptive responses. The sleep state can be divided into two states, namely non-rapid eye movement sleep (NREM) and rapid eye movement sleep (REM). Normal sleep starts with NREM, which is also known as slow-wave sleep with slow metabolism and decreased nerve cell activity. Depending on the depth of sleep and the degree of slow wave EEG NREM is subdivided into four stages, sleep onset, light sleep, moderate sleep and deep sleep. the REM sleep stage is fast wave sleep, alternating with NREM. Generally in one night will experience 4-6 NREM/REM cycles of 90-120 minutes each, with NREM getting shorter and REM getting longer. During the deep sleep stage, a large amount of growth hormone is secreted, which is important for human growth, development and repair. To sum up, people only enter the deep sleep state in the middle sleep period, deep sleep period, and rapid eye movement period, which is good for relieving fatigue. Deep sleep period is to make the brain rest, not the longer the better. And the duration of deep sleep is different for each person. Through some behavioral therapies, such as avoiding the intake of substances that affect sleep, having sufficient and regular exercise, and having a calm mind, you can sleep more solidly, and if necessary, you need to take medication to adjust your sleep as prescribed by your doctor.