How late is too late to stay up

How late is too late to stay up?

Staying up late can be divided into the following three situations:

(1) Stay up late: strictly speaking, more than 23 o 'clock even stay up late;

(2) Not staying up late but not recommended: habitually sleep late and get up late, barely not staying up late (sleep at 2 am every day, get up at 9 o 'clock the next day, do "every day" and "sleep for 7 hours" is not staying up late);

(3) It is more harmful than staying up late: sleep is not regular enough, sleep early and late, long and short (sometimes fall asleep at 10 PM, sometimes fall asleep at 3 am, sometimes sleep 10 hours, sometimes sleep 5 hours).

Long-term lack of sleep will weaken immunity, not only cause high blood pressure, heart disease, diabetes, etc., but also increase the risk of cancer and sudden death.