This paper introduces several theories, from simple energy-saving theory to complex theory involving memory processing, and makes a comprehensive discussion on human sleep.
There are two completely different states of sleep: fast wave sleep and slow wave sleep. What are their functions?
Scientists have found that sleep can be divided into two completely different States: one is called rapid wave sleep, and some people call this sleep state rapid eye movement sleep. As the name implies, the eyes move rapidly and the brain is very active during sleep, during which people dream.
The other state is called slow-wave sleep, which is the deepening of the first state, and the sleeper enters a deeper unconscious state. Scientists have found that fast-wave sleep and slow-wave sleep have different functions, and the two States also appear alternately during sleep.
Scientists agree that sleep is to rest the brain and cerebellum. Animals need to sleep, and brainless plants don't sleep; Some organs of the human body, such as the liver, do not rest. This shows that sleep is a unique phenomenon in the whole brain, and at least slow-wave sleep can make the brain repair the damage caused by free radicals. Free radicals are by-products of metabolism, which can damage human cells. Other organs can repair this damage by giving up and replacing damaged cells, but the brain can't do this. Only people can go to sleep, especially slow-wave sleep, and human tissues can use this rare "leisure time" for "emergency repair" operation. So what's the function of fast wave sleep? Some researchers have suggested that this is the "preparation action" and "arrangement action" that the brain does before entering slow-wave sleep, and it is a supplement to slow-wave sleep. However, some researchers disagree with this view, and think that fast wave sleep may be related to early brain development, but scientists who hold this view have not found convincing evidence.
Researchers have found that human sleep suddenly changes at the age of 20.
Our work and rest are controlled by the biological clock. This cycle is generally 24 hours. But it also varies from person to person. People with short work and rest cycles belong to lark type, and they all have the habit of going to bed early and getting up early; The other is called "night owl type", which is very active at night.
Jump, get up late in the morning.
Professor Tyr Ronnaberg of the University of Munich in Germany and his colleagues studied the changes of work and rest time in different periods of a person's life. The researchers surveyed 25,000 subjects between the ages of 8 and 90. After asking about their schedules, the researchers got some relevant data. Are teenagers sleepy in the morning because they go dancing in the ballroom at night, or because they want to go to the ballroom at night and "recharge their batteries" in the morning? Through the investigation, the researchers calculated the "average middle point" of their sleep, that is, the middle time between when they fell asleep and when they woke up.
The researchers compared these "intermediate points" with everyone's age and found that before the age of 20, children's sleep time will gradually extend. After the age of 20, this situation will suddenly change, and the time point will start to move forward again, that is, start to get up early. Professor Ronnaberg said that he was not sure whether this change was due to behavior or environmental factors. However, he believes that this sudden change in work and rest habits is related to human physiology. "For the first time, we found the time watershed at the end of adolescence."
He pointed out that this time change also shows that women develop earlier than men. According to the researchers' survey results, women's puberty generally ends at 19.5 years old, while men's end time will not come until 20.9 years old.
Scientists also found that too little sleep can lead to "sleep debt"
Scientists have found that the length of time that everyone needs to sleep depends on many factors, including age. For most adults, seven to eight hours a night is the best time to sleep. Of course, some people may sleep less, only five hours a night, while others may sleep longer, as much as 10 hours a day. If a person doesn't get enough sleep a few days ago, he or she will need more sleep time.
Too little sleep can lead to "sleep debt", just like overdraft in a bank. Eventually, your body will demand repayment of this debt. It seems that we can't adapt to sleeping less than we need. Even though we may be used to the daily work arrangement of reducing sleep, our functions such as judgment and reaction ability will be weakened.
When people reach old age, although they need as much sleep time as when they are young and middle-aged, their sleep will be more "shallow" and the time span will be smaller. In other words, there is less time to sleep at a time. Almost half of the elderly over 65 often face sleep problems, such as insomnia, and many elderly people often have short or no slow-wave sleep stages. This change is normal for the elderly, or it is a common health problem of the elderly, or it is caused by the treatment of these health problems.
Abnormal sleep may damage people's health, or cause confusion, depression and other emotions.
Sleep is closely related to health. If you don't sleep well, your body will be out of order. For example, problems such as stroke and asthma often occur at night or in the early morning, which may be caused by changes in hormones, heart rate and other sleep-related characteristics.
Almost all patients with mental disorders have sleep problems. For example, people with depression often wake up in the early morning and can't sleep anymore. Lack of sleep can also lead to seizures. If a healthy person is extremely short of sleep, it may lead to paranoia and hallucination stage of psychosis, and the interruption of sleep will lead to madness (excitement and hyperactivity) of manic-depressive patients.
People with other physical diseases, including Alzheimer's disease, stroke, cancer and head injury, often have sleep problems. These sleep problems occur when the brain regions and neurotransmitters that control sleep change, or when drugs that control other diseases are taken. Once sleep problems occur, it may damage people's health or cause confusion, depression, depression and other emotions. Patients who can't sleep will pay more attention to their pain and may take more painkillers.
Nowadays, people generally have a habit of "wasting energy", which will make people extremely lack sleep.
Researchers point out that if you feel sleepy during the day, it means you don't get enough sleep. If you fall asleep after lying for 5 minutes, it may be a serious lack of sleep. Sometimes there will be short-term sleepiness when awake (especially paroxysmal sleepiness of people who lose normal sleep, usually lasting only 1 to 10 seconds) or short-term sleep phenomenon, which is another sign of lack of sleep. Many times, people don't know that they have experienced a brief lethargy. Nowadays, people generally have a habit of "wasting energy", which will make people extremely lack sleep.
Many studies clearly show that lack of sleep is dangerous. Using driving simulator or hand-eye coordination, it is found that people who lack sleep perform as badly as or even worse than those who are drunk. Lack of sleep will also increase the harmful effects of alcohol on the body, so a tired person drinking will be more harmful than a well-rested person drinking.
Why do people sleep?
Sohu health channel
Obviously, sleep is necessary. But if you ask: Why do individuals have to sleep? If you don't sleep for several days in a row, what are the physical and mental consequences? Such a question has never been answered in psychology.
Right "Why do individuals have to sleep?" So far, there are three different explanations for a problem:
1. biological clock and daily rhythm
In 24 hours a day, individuals show periodic activities in birth; When to sleep, when to eat, when to work, and when to queue () almost all have a certain order, which is almost determined by personal physiological operation. Such a 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, except for personal living habits (for example, the biological clock of people who often work at night shift is different from that of ordinary people). For example, the temperature changes obviously in one day, and the body temperature changes obviously in one day. When the ambient temperature drops and the body temperature drops, individuals will have the need for sleep. The daily temperature variation law is the lowest from midnight to around 5 am, and the human body temperature is also the lowest during this time. Therefore, for the vast majority of people, in Rosty Yi, from eleven o'clock to six o'clock in the evening, it is sleep time. Therefore, the biological clock is also called the circadian rhythm.
For animal life, the daily rhythm is very dominant. Therefore, the migration of migratory birds or fish mostly moves in the same longitude range in the north-south direction on the earth to maintain its periodic physiological clock. The activities of human ancestors, like other animals, started at sunrise and ended at sunset. However, with the rapid development of modern transportation and the flight of jet planes, the distance between the two sides of the earth has become dawn to dusk; Flying from Taibei to new york just happens to be upside down in the morning and evening, which makes people encounter the problem that sleep is difficult to adapt. This phenomenon is called jet lag. The common symptoms of jet lag are: physical and mental fatigue, loss of appetite and temporary sleep disorder. The trouble degree of flight time difference varies with the flight direction; When flying towards the sun (westbound to Europe), the flight time difference is less troublesome; When flying against the sun (eastbound to America), the flight time difference is more troublesome. The sleep disorder caused by jet lag usually disappears within three days to one week, and the personal physiological clock is re-established in the new environment.
2. Repair theory and maintenance theory
Recovery theory and conservation theory are two theories to explain the necessity of sleep. According to the theory of recovery, sleep can restore energy and eliminate fatigue. Recovery theory refers to recovery, including both physical and psychological aspects. Physiologically speaking, if an individual stays awake, he can't fully rest, and neither the conduction of the nervous system nor the operation of muscle glands can complete metabolism in time. It is a truth that you need sleep and rest after physical exertion, just like you need to supplement your diet after nutrient consumption. Man's physical strength is like a reservoir. When the water in the reservoir is consumed to a certain extent, it is necessary to temporarily close the outlet or reduce the water output to increase the water storage capacity of the reservoir and maintain the long-term water supply function. The recovery of this physiological level mostly occurs in the deep sleep stage.
On the psychological level, sleep can help individuals complete their mental activities that are not over when they are awake. Experiments of learning psychology have long proved that people who sleep immediately after practice will have better memory after waking up. The reason is to fall asleep immediately after practice, so as to continue to complete the unfinished information processing work during sleep. According to this psychological recovery, most of them occur in the shallow sleep stage. Dreaming is a kind of psychological activity, and the situation of dreaming is often related to life during the day. Even problems that cannot be solved during the day may be answered in dreams, which can also be used as evidence that sleep has a restoring function. According to the research of psychologists, dreams only occur in the shallow sleep stage.
Maintenance theory is a supplement to repair theory. According to the maintenance theory, the reason why individuals need sleep is mainly to preserve their energy and vitality, so as to avoid excessive fatigue and damage their health. In other words, for maintaining the normal function of body and mind, sleep has the function of automatic adjustment.
3. Evolutionary theory
In addition to the above two theories, there is another complementary theory to explain the necessity of sleep, which is called evolution. According to the theory of evolution, except that individuals have to sleep, all kinds of animals, including humans, show different types of sleep patterns, mainly because they have evolved for a long time in the process of survival. Humans sleep at night and have a fixed place because they lack the ability to walk at night; In order to ensure safety and avoid the invasion of wild animals, the adaptability of building houses first evolved in the nest. Cattle, sheep, camels and other animals sleep in stages because they live in the wild all the year round and have no fixed place. They must sleep and rest at any time and wake up at any time in order to escape at any time when attacked. There is no fixed point and time for these animals to eat and live, because they live on the grassland and have grass to eat at any time. In addition, some animals, such as frogs and snakes, can't go out for food in winter, but they lack the migratory ability like migratory birds, so they have evolved the ability to hibernate after long-term adaptation to the environment.
Sleep is necessary for individuals, such as long-term lack of sleep or deprivation of sleep time, what impact will it have on people's body and mind? Psychologists have done a lot of experimental research in the past, and the results obtained are quite consistent and quite unexpected. In the experiment of sleep deprivation (not allowed to sleep or staying awake voluntarily during sleep), the longest record is 200 hours (more than eight days). The results showed that the subjects were extremely tired and sleepy, and there was no obvious abnormality in their physical and mental functions. Even psychologists have found that the performance of subjects who stay awake for 1 1 day has not been greatly affected.