Or just to give two examples, your biological clock is to get up at noon 12 and go to bed before 4 am, not counting staying up late. Because the sleep time of 4: 00 and 8 hours is 12. Then if you go to bed after 4 o'clock, go to bed at 5 o'clock and start at 12 o'clock, then you can stay up late. But now everyone is not so early. Some people like to sleep after 12 and 1, and wake up regularly the next day. This is not impossible, as long as they keep their own routine. I am used to watching my mobile phone before going to bed at night. If my mobile phone leaves my hand for a period of time, it will feel like Sanqiu, leading to the habit of brushing my mobile phone before going to bed.
From the perspective of TCM health, I suggest you go to bed around 9- 10 at night. If it exceeds 1 1 pm, it is generally considered to be staying up late. It's best if you fall asleep, but how many people can sleep around 23:00 at night, if nothing else, there are not a few people who brush headlines at night, so it is difficult for modern people to avoid staying up late.
Generally, staying up late is harmful to the body, especially the kidneys are prone to collapse. The phenomenon of people staying up late is also divided into age and fatness. A fat man, they are more sleepy. Thin people stay up late and sleep less. The disadvantage is that thin people can't keep up with fat people. The most extreme thing I tried was that I was conscious after 4 am, and then I fell asleep like a dream. It's enough to get up and go to work after sleeping for less than three hours and continue to work at night.