Sleep 8 hours a day, if the sleep time are in the night, and regular work and rest time, it is not considered to stay up late, otherwise it is considered to stay up late. Currently there is no clear information to show the specific criteria for staying up late, but according to people’s normal work and rest habits to judge, every day before 12 midnight to go to sleep, and to ensure that 8 hours of sleep, the next day’s state of mind, basically no fatigue and sleepiness, generally are not considered to be staying up late. However, if more than 12 midnight to sleep, or for various reasons at night without sleep, even in the daytime supplemental sleep 8 hours, should also be considered late, long-term late night will cause some harm to the human body, such as skin luster, easy to acne and pigmentation; mental fatigue, reduced immunity, prone to disease; visual function is reduced and so on. Therefore, you should develop a regular routine of going to bed early and getting up early to avoid staying up late, otherwise it will damage the body. Patients who are unwell due to staying up late should go to a regular hospital in time to be treated under the guidance of a doctor, and should not be negligent so as not to affect their health.