Related information: In fact, we know very little about the role of sleep.

Humans have landed on the moon, and even know something hundreds of thousands of light years away, but we know little about one thing that we can't do every day-sleep.

Aristotle thought that "sleep is the steam that cools the mind". It sounds a bit silly, but it is true that modern people's views on sleep are not much smarter. Scientific and mythological works explaining sleep and dreams are really overwhelming. No one can deny that sleep is necessary, but the research on people and animals has not proved that sleep deprivation will cause permanent physiological damage to people or animals, but only temporary neuropsychiatric changes, which is very different from people's previous understanding.

So far, there is no theory that can convincingly explain why people need sleep. At present, the research and understanding of sleep is still very preliminary. Because one-third of a person's life is spent in sleep, the importance of sleep is self-evident. From a medical point of view, in order to solve the very common problem of sleep disorder in clinic, it is very necessary to conduct in-depth research on sleep.

Modern medicine generally believes that sleep is a necessary rest to restore energy. As an unconscious state of happiness, it usually happens when we lie in bed and allow ourselves to rest at night. Compared with the awakening state, when people sleep, their contact with the surrounding environment stops, their conscious consciousness disappears, and they can no longer control their words and deeds. Sleeping people relax muscles, weaken nerve reflex, lower body temperature, slow heartbeat, slightly lower blood pressure, slow metabolism and obviously weaken gastrointestinal peristalsis. At this time, it seems that the sleeping person is static and passive, but it is not. If we give a person an EEG during sleep, we will find that the electrical pulses emitted by brain cells during sleep are not weaker than when they wake up. This proves that the brain has no rest. Just like a hive at night, it looks as if all the bees have returned to their nests to rest, but in fact all the bees are busy making honey all night.

Sleep is the function of the brain

We can control our sleep.

If consciousness is the function of the human brain, then sleep is also the function of the human brain. We talk, walk and eat, which are the functions of specific motor centers in our brains. We feel cold, hot, painful and itchy, which are the functions of specific sensory centers in our brain. Also for sleep, it is still an active function of the central nervous system. Sleep is not a passive process as many of us think. Now we think it is an active behavior, and it is controlled very accurately, not simply not awakening. But people have not found a fixed sleep center so far.

Sleep mechanism is related to extensive brain activity. There is a structure in human midbrain called reticular ascending excitation system, which is of course much more complicated than our computer network. If the reticular ascending excitation system is inhibited by the cerebral cortex, it will enter a sleep state. The cerebral cortex is the highest command of our human body, so sleep is controlled by our consciousness. In other words, if sleep happens, we must want to sleep. If we don't want to sleep, we can also control ourselves from sleeping. Just like a guy in our village who played computer games for three days and nights, his eyes are wide open and he is tireless. Of course, the ability of the cerebral cortex to control the reticular ascending excitation system varies from person to person, and the disorder of control leads to various sleep disorders, such as insomnia.

After falling asleep, if there are no special circumstances, we will wake up, because of course we will not sleep forever. So, how did sleep end? This is because there is a biological clock in our brain, which may be related to a nerve nucleus called pineal gland. This is the natural clock in the human body. Taking 24 hours as a cycle, its accuracy can reach 1%, and the daily error is less than 5 minutes. This is why many people wake up before the alarm clock rings. In addition to the biological clock to wake up sleep, external or internal strong stimulation also has the same effect. Such as strong light, strong sound, defecation and so on, can make people awake.

sleepless night

When we sleep, we can't stop dreaming.

Although our contact with the surrounding environment has basically stopped during sleep, in fact, the metabolism of the brain has not declined. If we do EEG, at this time we find that EEG is not a line (if it is a straight line, it must be brain death if deep anesthesia is excluded). According to the changes of EEG, sleep can be divided into two periods: slow wave sleep and fast wave sleep. In sleep, as long as the sleep time is long enough, these two periods always appear alternately.

During slow-wave sleep, EEG is slow-wave and there is no eye movement. It is a stage from drowsiness to deep sleep, which can be divided into four stages. This question is generally not a dream.

When you fall asleep (the first stage), when you feel sleepy, the EEG begins to change, the α wave decreases, the θ wave appears, and the EEG wave pattern flattens. This period is sometimes called "transitional sleep" because it marks the transition from awakening to sleep. This problem is easy to wake up.

In the shallow sleep stage (stage ⅱ), the α wave disappears completely and sharp waves appear. This period is the easiest time to fall asleep, and people with insomnia often wake up many times during this period, but they can't smoothly enter the next period.

In the middle stage of sleep (stage ⅲ), the sleep is deep, and spindle bursts appear intermittently on EEG. At this stage, consciousness disappears and it is easy to wake up, which lasts about 1 hour.

Deep sleep (Ⅳ) lasts about 30 minutes, during which it is difficult to wake up. Electroencephalogram showed high pressure dome δ wave. After the deep sleep period, it will enter the next period, the fast wave sleep period.

Active sleep REMS is also called rapid wave sleep period, because the most striking feature of this period is rapid eye movement period. The changes of EEG are similar to those at the beginning of sleep, showing θ wave. This period of deep sleep is still difficult to wake up. If you insist on waking him up at this time, my friend Mr. Freud can do his best, because about 80% people will tell the details of their dreams vividly. In addition to eye movements, the muscles of the hands and face contract irregularly and the skeletal muscles relax. The autonomic nervous system is unstable, and the sympathetic and parasympathetic nerves are dysfunctional, resulting in uneven breathing, different pupil sizes, unstable heart rate and blood pressure, and increased cerebral blood flow. Male penis erection, female vaginal wall allows blood. Talking in a dream, having nightmares, enuresis, nocturnal emission, etc. It also happened at this time.

The above two sleep states appear periodically. Slow-wave sleep first appeared. After the first 90- 100 minutes, it went through four stages of slow-wave sleep, then returned to stage 2, followed by rapid eye movement sleep, and returned to slow-wave sleep after 15-20 minutes. Rapid eye movement sleep gradually increases at night, but it accounts for about 25% of the whole sleep time of adults on average.

The Relationship among Sleep, Dream and Memory

Rapid eye movement sleep is closely related to memory.

My friend Mr Crick, the guy who once won the Nobel Prize for explaining the double helix structure of DNA, is also. He put forward the idea that people will "learn backwards" during REM sleep. He believes that when the brain stores too much information, there will be transmission problems, and dreaming can eliminate useless information in recent memory and turn recent memory into long-term memory. It's a bit like ScanDisk in Win95. We scan our brains at night to see if there are any mistakes and correct them if there are. But Mr Crick was born a few years earlier and has never played computer. He explained that after sleep, people extract short-term memory information from the reticular structure in the middle of the brain and send it to the occipital lobe, so the dream begins and the worthless information is deleted (I don't know how to filter it). Make a backup of valuable data and save it in the temporal lobe and parietal lobe of the cerebral cortex. This is how long-term memory is formed.

Although Mr Crick's view has not been finally confirmed, in the experiment of depriving animals of rapid eye movement sleep, it can be observed that the memory of animals is obviously reduced.

Biochemical mechanism of sleep

A substance called sleep-promoting polypeptide

After taking sleeping pills, people will feel sleepy. This is because a chemical enters the human body and acts on the sleep center in the brain. Some scientists imagine whether animals will produce certain chemicals in the process of constant awakening. When this chemical gathers to a certain concentration, sleep will occur.

Some people just like asking questions. These people are scientists. 19 10, a man named Pieron deprived the dog of sleep 150-293 hours (I don't know how hard his old man had to work), and then pumped out the cerebrospinal fluid of the dog (our brain is actually soaked in a liquid, and the liquid around the brain is cerebrospinal fluid) and injected it into the ventricle of the awake dog. So, Mr. Piron, Many later scientists, such as maunier and China scholar Liu Shiyi, made great efforts to extract a substance called δ-sleep-inducing peptide. If this substance can be produced in large quantities in the future, it will be a sleeping pill with few side effects.

Recent studies have also found that the content of growth hormone increases obviously during sleep, especially in the third and fourth stages of slow-wave sleep, so sleep is also related to our height. This can also explain why babies especially need sleep.

Sleep time

Just as everyone's appetite is different, everyone needs different sleep time.

One year, my teacher founded a university in Shandong. His favorite student, the representative of literature class, Mr. Zaiyu once had lunch, was idle and sleepy, and fell asleep. President Kong happened to inspect the student dormitory that day. Seeing Jae-woo sleeping, he lost his temper, grabbed Jae-woo's ear and called him "a dead wood cannot be carved". His old man's scolding doesn't matter, so many of his disciples, such as Mr. Dong Zhongshu and Mr. Zeng Guofan, are afraid that President Kong will pull his ear.

In fact, taking a nap is not a sign of laziness. Studies have shown that taking a nap, even if it is only 15 to 30 minutes, can greatly improve the work efficiency in the afternoon, and its effect is even more than three cups of strong tea.

Everyone's sleep time varies greatly, with an average of about 8 hours. Some people may need 4 to 5 hours, and about 10% of healthy people belong to this situation. 15% of them slept more than 8 hours or more. Sleep time is different at different stages of a person's life. Newborn babies need to sleep 16 hours or more every day. As time goes by, the sleep time decreases with the growth of children, and puberty takes about 8 hours, which is relatively longer than that of adults. In adulthood, everyone is stable in their own unique sleep habits; Generally, after entering old age, sleep time gradually decreases. For example, if an adult or an elderly person sleeps more than 10 hour or less than 4 hours, it is necessary to consider whether this person has any problems and needs to go to the hospital for examination. In addition, due to the change of physiological state, the sleep time required by the same person in different periods will also increase or decrease. For example, women may sleep more during menstruation, and pregnant women often need more than 10 hours of sleep every day. After heavy physical labor or physical exercise, sleep time will generally be prolonged, while excessive mental labor will often reduce sleep. So we can't generalize how much sleep people need.

President Kong is old. Of course, his sleep time is reduced and he can't take a nap. It's really meaningless to scold him and kill him. If he installed a computer in his old man's office, surfed the Internet, played for three dozen times and didn't leave (www), and accidentally read my article, I'm afraid his point of view will change.

By the way, sleep should not only have a certain amount, but also have quality. High-quality sleep makes you energetic, energetic and quick-thinking after waking up. But some people have poor sleep quality, either dreaming more or waking up early. This kind of sleep is very long and they are still listless during the day.

Sleep deprivation test

What effect does lack of sleep have on people?

What happens if people 10 days 10 nights don't sleep? 19 10 years, in order to verify that an "endogenous sleep-promoting substance" can be produced in animals, Mr. Piron once kept a poor dog awake for 293 hours. After his old man's house, 1966, a 23-year-old Japanese boy volunteered not to sleep, and he insisted on10/hour. Later, many scientists used volunteers to carry out many sleep deprivation experiments for up to 200 hours. The final conclusion of these experiments is that the consequences of sleep deprivation are not as serious as we thought. These sleep-deprived people hardly found any physical damage. More serious problems are mental or psychological, such as severe fatigue, difficulty in concentration, decline in learning and memory ability, and serious hallucinations, such as auditory hallucinations and hallucinations. And some people just show that they are particularly greedy, which leads to weight gain.

Although sleep deprivation can cause the above psychological abnormalities, as long as the subjects sleep for 10 hour, they can basically recover completely. If we further study the subjects, we can find that the time of slow-wave sleep first increases in the first few nights of sleep recovery, but the increase of REM sleep is not obvious. After a few days of slow-wave sleep increase, fast-wave sleep also begins to increase. This proves that slow-wave sleep and fast-wave sleep have their own functions and cannot replace each other.

Why study sleep deprivation? The purpose is to understand the possible consequences of insufficient sleep. For example, the prolonged slow-wave sleep time may be related to the acceleration of protein synthesis and physical recovery of people who are exhausted by heavy physical labor during slow-wave sleep. During fast-wave sleep, the cerebral blood flow increases, the baby's brain develops rapidly, and the fast-wave sleep period is obviously longer, indicating that sleep during this period is related to the development and growth of the brain. Therefore, the lack of sleep in infants not only affects the growth of the body, but also may affect the normal development of the brain. Insufficient sleep in adults not only affects physical recovery, but also is not conducive to mental health. Lack of sleep in the elderly may accelerate brain aging. Therefore, a good sleep is very important for people.