Generally more than 11:00 did not go to bed after even stay up late, but due to the different habits of each person, what time is considered to stay up late can not be generalized. Normal adults, daily sleep time should be maintained at about 8 hours, generally about 10:00 p.m. every night into sleep, the second day of 6:00 a.m. to get up, belong to the normal routine. 12 o’clock to 2 a.m., belong to the best time to sleep, after 11 o’clock has not gone to bed, basically belong to stay up late. Everyone’s sleep schedule will be different in life. More than 12 o’clock may lead to disruption of the patient’s biological clock, it is difficult to enter a deep sleep, affecting the quality of sleep. It may also lead to endocrine disruption, which in turn affects physical health. In daily life, it is important to develop good habits to ensure good health.