The sleep time frame varies from person to person, and the normal sleep structure is divided into two periods: non-rapid eye movement sleep (NREM) and rapid eye movement sleep (REM). NREM and REM alternate, and the alternation is called a sleep cycle, and the two time phases are cyclic. Of course, sleep time is not the longer the better, too much sleep and too little sleep are not conducive to health. So how long is it healthy to sleep? In fact, the sleep requirement time is different for people of different ages. Generally speaking, the sleep requirement time decreases with age. Babies have the longest sleep requirement, needing 20~24 hours of sleep per day, toddlers need 9~12 hours, school children need 9~10 hours, adults need 7~9 hours, elderly people have the shortest sleep requirement, 6~8 hours, but those older than 80 years old have a relatively high sleep requirement, 9~10 hours. Sleep disorders and diseases are mutually causal With the accelerated pace of people’s lives, overtime work and overnight entertainment are commonplace for urbanites, so sleep deprivation is also a relatively common problem at present. Studies have shown that insomniacs are several times more likely to suffer from cardiovascular diseases than normal sleepers, and the biological changes caused by sleep deprivation are surprisingly similar to the aging phenomenon, which also means that people who do not get enough sleep are prone to aging. According to studies, too much or too little sleep can increase the incidence of various diseases. Prolonged sleep disorders often cause daytime dysfunction (work ability, cognitive function), low human immunity, irritability, and also predispose to hypertension, diabetes, obesity, cardiovascular and cerebrovascular accidents and psychological disorders, and even cause sudden death. Sleep disorders can cause a variety of diseases, and similarly, sleep disorders can be caused by a variety of reasons. Different kinds of chronic diseases, such as pain, heart failure, chronic lung disease, chronic kidney failure, Parkinson’s disease, cerebrovascular disease, encephalitis, etc.; primary sleep disorders, such as obstructive sleep apnea syndrome, periodic limb movement and restless legs syndrome, etc.; psychological and psychiatric disorders, such as anxiety (difficulty falling asleep), depression (early awakening), schizophrenia, reactive psychosis, etc. Comprehensive conditioning to help sleep peacefully sleep is to a considerable extent a habit, and thus maintaining good sleep habits and following the natural laws of sleep is the best way to prevent sleep disorders. In addition, it is important to understand the possible causes of insomnia, eliminate the factors that affect sleep, self-regulate and improve the bad mood. How can I improve my sleep? 1, the rest time should be regular, before going to bed to relax the mind; 2, every day on time to get up, even on holidays can not stay in bed; 3, the bedroom environment should be comfortable, the temperature is appropriate, generally recommended to maintain at 18 ~ 24 ℃, avoid bright light, noise, etc.; 4, the daily moderate regular activities; 5, dinner should not be too full, after the meal does not drink alcohol, coffee, tea, do not smoke; Finally, insomniacs should avoid napping during the day.