Sleeping 8 hours a day if it is normal to go to sleep at 11:00 pm and get up at 7:00 pm is not considered staying up late; if you go to sleep at more than 11:00 pm, even if you sleep 8 hours a day, it is still considered staying up late. Staying up late is very harmful to the body, mainly digestive disorders, endocrine dysfunction, increase the risk of cardiovascular and cerebrovascular diseases and other hazards. 1. Digestive disorders: the night is a time for the liver to detoxify and the gastrointestinal tract to rest. Often stay up late may cause liver function abnormalities, gastrointestinal burden increased, triggering some digestive system diseases. 2. Endocrine dysfunction: often stay up late will cause the body endocrine metabolic function disorders, in the growth period of the child, will affect its growth and development. 3. Increase the risk of cardiovascular disease: often stay up late, the spirit continues to be in a state of fatigue, will increase the risk of hypertension, high blood cholesterol, diabetes and other cardiovascular diseases. It is recommended to maintain a normal regular work and rest, reduce the number of late nights to avoid adverse consequences.