1, the role of biological clock and daily rhythm:
In 24 hours a day, individuals show periodic activities in birth; When to sleep, when to eat and when to work, there is almost a certain order, which is almost determined by personal physiological operation. This physiological function that determines the periodic life activities of individuals is called biological clock. The formation of biological clock is mainly determined by the change of 24 hours a day. There is the sun during the day, which is convenient for human work and activities. Night is suitable for rest and sleep.
2, sleep is the need to maintain and restore physical strength:
Sleep can restore energy and eliminate fatigue. The reason why individuals need sleep is mainly to conserve energy, so as to avoid excessive fatigue and harm health. After activities and work during the day, the human body will be tired and sleepy. At night, there will naturally be a need for sleep, which has an automatic adjustment effect on maintaining normal physical and mental functions.
3, biological evolution theory:
The reason why humans and various animals show different types of sleep patterns is mainly due to their long-term evolution in the process of survival.
4, sleeping at night, but also because the human brain will secrete a melatonin at night, which can promote sleep, but not during the day.