Studies have shown that normal adults sleep 6-8 hours a day, and those who sleep 7 hours a day have the lowest mortality rate. Normal sleep time is not exactly the same depending on age and individual differences. During sleep the cerebral cortex is at rest and physical strength is restored, so sleep is indispensable in order to maintain good health. Chronic sleep deprivation can lead to many diseases more likely to occur. People who sleep less than 6 hours per night are 2.5 times more likely to develop type 2 diabetes than those who get a moderate amount of sleep. However, more sleep is not better. People who get more than 8 hours of sleep each night are 30% more likely to have a stroke. Minors need more sleep than adults because of their growth and development. Newborns should sleep no less than 11 hours a day, week-old newborns sleep 16-17 hours a day, and 1-4 months, 14-16 hours a day. Infants should not sleep less than 10 hours a day, otherwise normal growth and development will be affected. Primary and secondary school students should not sleep less than 8 hours a day to avoid affecting their learning efficiency. As people grow older, their ability to sleep gradually decreases, their sleep time is gradually shortened and their sleep quality becomes lower and lower. From the point of view of being beneficial to the body, the elderly should also try to maintain 6-8 hours of sleep as much as possible.