The Secret Of Sleep Time

Zheng Lei / Wen

Many people's sleep quality is poor, insomnia or lack of sleep exist at the same time, some people will be energetic at a certain time in the middle of the night, some people have difficulty getting up in the morning. It seems that everyone has his own set of work and rest time, which is the "biological clock". "Why do we feel tired" explains the neurophysiological reasons behind these phenomena. We can adjust work and life habits and better improve sleep quality.

One of the manifestations of "the unity of man and nature" is that everyone depends on day and night, that is, the influence of light on human life. People feel light and dark through the eyes, and transmit the information to the clock neurons in the suprachiasmatic nucleus, and then transmit the day and night information to all parts of the body. Every station in the process - Information receptors, cells, other parts of the brain (such as the sleep center) or organs including the liver - forms a circadian rhythm, like the clocks and hands. This "body clock" controls our metabolism and almost all of our body functions. About 15% to 40% of our genome's genes turn on or off at certain time points in the biological clock.

Although everyone's biological clock timing is different, but "early rising syndrome" has appeared in almost many people. The current working hours are too early for more than 60% of the population. People's sleep time at night changes with age. Children fall asleep relatively early, and then gradually become late. In their adolescence, they become owls. When they are about 20 years old, they fall asleep at the latest value, and then they begin to get earlier. The average age of women reached the latest value at 19.5 years old, while that of men reached the latest value at 21 years old. That's why older people and children go to bed early.

In modern society, people fall asleep late, and more than 60% of them find it difficult to concentrate at 8 o'clock in the morning. However, the established social conventions force people to get up around 6 o'clock. This time is also known as "social time.". Therefore, there is a "time difference" between the biological clock and social time. People work and live according to social time for a long time. Lack of sleep time may cause health and mood problems. The symptoms of social jet lag syndrome are also the most severe for growing teenagers - they have to get up early to go to school. Teenagers need 8 to 10 hours of sleep, but sleep is reduced on school days. A survey of senior high schools shows that students who keep more than eight hours' sleep jumped from 35.7% to 50% after one hour of school delay. Attendance, academic performance, activity, and even eating habits improved significantly with the postponement of school time. Once allowed, the students will fall asleep in the morning, directly into REM, indicating that they are still in physiological sleep, although they seem to be awake. It seems that the education authorities should consider delaying the schooling time of primary and secondary school students by one hour so that they can have better sleep quality.

The time difference between social time and the body's biological clock formed according to the rise and fall of the sun is rarely less than 30 minutes. Especially in large countries like China and the United States, which span nearly one sixth of the earth, if only one time zone is implemented, different social times need to be determined separately. For example, Xinjiang's work, lunch break, off work and dinner are two or three hours later than those in the eastern region.

For adults, due to the pressure of social life in the industrial society, we must adjust our work and rest time, and those who go to bed late must form the habit of going to bed early. Factors that determine sleep are our circadian clock, the interval between wakefulness, and the level of sleep stress. Sleep pressure will gradually reduce, so to the second half of sleep, wake up the trend gradually strengthened. Our body temperature bottoms out in the second half of sleep, which allows us to sleep for a few hours, even though sleep stress has been reduced by more than half. We have the fastest increase in sleep stress in the first half of our waking time, so we feel quite tired at noon. We can adjust the light, temperature and so on, let the body's clock gradually change the time of sleep. If our body temperature and brain temperature drop, we become tired and easy to fall asleep.

However, the flexibility of human body clock adjustment varies from person to person. Due to genetic reasons, some people's internal clocks are longer than the earth's rotation cycle, while others are shorter. In the long history, the earth's rotation speed has become slower and slower. In most people, the cycle of a day is longer than 24 hours. People can also adjust their circadian clocks briefly when they travel across countries. It takes about a day for the internal clocks to adapt to the new light and shade changes every time they pass through a time zone. When we travel westward, we fall asleep earlier and travel eastward later. Most people can adjust their time difference relatively easily when traveling west, that is, their body clock has a longer cycle of the day. For those who go to bed very early, it is easier and faster to adjust the time difference when traveling from west to East. Maybe human beings will be able to immigrate to Mars one day, and the day there will be longer than that on earth. Therefore, for the earth people living on Mars, their biological clocks will become earlier types of sleeping, and people will be more energetic and energetic in the morning.

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