People can not stay up late to sleep, at least not often, more than 1:00 a.m. after sleeping are called staying up late. Because the human body’s best sleep phase is deep sleep to more than 4 hours, and in the morning 0-4 points if the deep sleep, for the body belongs to the best case. There are many factors that can not stay up late: First, staying up late will cause the body’s immune system to be low, the ability to fight disease is diminished. Second, when staying up late will also cause irreversible burden and impact on the cardiovascular, cerebrovascular, aortic system. Third, long-term late night will cause excessive fatigue of the human body, which will lead to subhealth conditions. Fourth, long-term late night will also cause plant nerve dysfunction, which will affect the body’s work efficiency.