Normal people sleep for about 6-8 hours a day, and deep sleep usually accounts for about 25%-40% of the total sleep time, so it is normal to have about 2-4 hours of deep sleep every day. Deep sleep is also known as the golden sleep period, people generally sleep at night in the deep sleep and light sleep alternately, in the state of deep sleep, the patient’s cerebral cortex function is in a state of full rest, the functional activity of the cerebral cortex is extremely low, for eliminating the fatigue of the patient’s body and brain fatigue, restore energy and anti-disease and metabolism have a very important role. It is important for the elimination of physical and mental fatigue, the recovery of energy, the fight against diseases and metabolism. Therefore, it is important to evaluate the quality of sleep not only by the length of sleep, but also by the duration of deep sleep and the quality of sleep.