Sleep is often an unconscious state of happiness, which usually happens when we are lying in bed and when we 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 a spontaneous and reversible state of rest in higher vertebrates, which is characterized by decreased responsiveness to external stimuli and temporary interruption of consciousness. The activity of normal human brain, like the brains of all higher vertebrates, is always in a state of alternating awakening and sleep. This alternation is one of the biological rhythm phenomena. When awakening, the body's sensitivity to internal and external environmental stimuli increases, and it can make a purposeful and effective response. On the contrary, when sleeping, the body's sensitivity to stimulation decreases, muscle tension decreases and reflex threshold increases. Although it still maintains the function adjustment of the autonomic nervous system, all complex higher nervous activity activities, such as learning, memory, logical thinking, etc. , can't carry out, only keep a few activities with special significance. For example, the cry of a mouse can wake a sleeping cat; Babies cry easily to wake their wet nurses. Besides periodicity, sleep is reversible and spontaneous. The former means that the sleep state can be awakened by external or internal strong stimulation; The latter means that the occurrence of sleep is endogenous, although it is sometimes influenced by the environment and some chemical factors to some extent. The above three characteristics are helpful to distinguish sleep from other sleep States. For example, hibernation is mainly caused by the temperature drop of the external environment, while coma and lethargy are characterized by the irreversibility of sleep state. Hypnosis is a sleep-like state induced by suggestion. The hypnotized person's consciousness is not lost, but his behavior is dominated by the hypnotist's suggestion. Some people study that dreams appear periodically during sleep, accompanied by unique physiological characteristics. Some people think that dreams are the third state independent of awakening and sleep. In fact, these three states are closely related internally. For example, long-term awakening will lead to "compensatory" sleep and an increase in dreams.
Sleep has always been an interesting research topic, because about13 of a person's life is spent in sleep, which can restore the spirit and relieve fatigue. From the beginning of the 20th century, with the help of EEG analysis, it was found that EEG activity showed a special slow wave during sleep. From 65438 to 0952, it was found that short-term rapid eye movements often occurred during sleep, accompanied by rapid and low-amplitude brain waves. This important discovery has led to the vigorous development of sleep research. It has been proved. Sleep is the active process of the brain, not the cancellation of passive awakening; Many neural structures and transmitters in the brain participate in the occurrence and development of sleep (thus carrying out physiological research of dreams and differential diagnosis and treatment of clinical sleep disorders, etc.). But up to now, we still know little about the origin, mechanism of occurrence and development, physiological basis of phase change, and how sleep can eliminate fatigue.
Normal sleep consists of two alternating phases, one is slow wave phase, also known as non-rapid eye movement sleep, and the other is heterogeneous sleep, also known as rapid eye movement sleep. At this time, the rapid eye movement period occurred, and dreams often appeared. Non-rapid eye movement sleep is mainly used to restore physical strength, and rapid eye movement is mainly used to restore brain power.
According to the characteristics of human brain waves, slow-wave sleep is usually divided into four different stages, which correspond to the process of sleep from shallow to deep. 1 phase presents low-voltage brain waves with mixed frequencies, with the frequency of 4 ~ 7 cycles/second as the main frequency, which often appears at the beginning of sleep and after a short awakening at night. The second phase is also a low-voltage brain wave, which is a short burst of 12 ~ 14 cycle/second sleep spindle wave with K complex wave inserted in the middle, which is the main component of slow-wave sleep and represents the shallow sleep process. In the third phase of EEG, short-term high voltage waves often appear, exceeding 50 microvolts, and the frequency is 1 ~ 2 cycles/second, which is called δ waves. In the fourth stage, the delta wave is dominant, and its appearance time accounts for 50% of the total time, representing the deep sleep state. Therefore, there are only quantitative changes in the third and fourth periods, and there is no qualitative change. It is generally believed that the fourth stage of slow-wave sleep has the function of eliminating fatigue, because after a long period of physical labor or no sleep, this stage lasts for a long time in the recovery of sleep. With the sleep from shallow to deep, consciousness gradually loses, blood pressure drops slightly, heart rate and respiration slow down, pupils shrink, body temperature and metabolic rate decrease, urine volume decreases, gastric juice increases, saliva secretion decreases, sweating function increases, etc.
Heterogeneous sleep is a state of excitement that appears periodically during sleep. EEG shows high-frequency and low-voltage waves, similar to brain waves when awake. Autonomic nervous system activities are enhanced, such as increased heart rate, accelerated breathing, increased blood pressure, increased cerebral blood flow and oxygen consumption, penile erection, etc. In addition, the sleeper will turn over from time to time, and the muscles of the face and toes will twitch from time to time. In experimental animals, the discharge activity of a single nerve cell is not only higher than the slow-wave phase, but also higher than the activity level in awake state sometimes. Like animals, people's heterogeneous sleep shows three characteristics: ① low voltage and fast brain waves; ② The relaxation of cervical muscle tension and spinal cord reflex are inhibited, and the motor system is strongly inhibited at this time; ③ Rapid eye movements occur frequently, and high sharp waves appear in some brain structures related to vision, including the visual area of cerebral cortex, which are collectively called pons-geniculate-occipital cortical waves (PGO). Because REM only exists in heterogeneous sleep, which is often called REM sleep.
Transition of sleep phase When a normal adult falls asleep, he first enters the slow-wave phase, which usually lasts for 70 ~ 1 ~ 2 ~ 3 ~ 4 ~ 3 ~ 2, that is, he turns to heterogeneous sleep for about 5 ~ 15 minutes, thus ending the transition of 1 phase. In the whole sleep process, there are generally 4 ~ 6 transitions, the duration of slow wave phase is gradually shortened, mainly in the second phase, while the duration of out-of-phase phase is gradually extended. When full-time sleep 100%, slow-wave sleep accounts for about 80% and heterogeneous sleep accounts for 20%. Arranging different sleep stages and waking states in chronological order can draw a sleep chart, which can directly reflect the dynamic changes of sleep stages.
The depth of sleep is generally measured by physical activity and decreased sensory sensitivity. In addition, some physiological indexes, especially the awakening threshold, also indicate that the third and fourth stages of slow wave phase are deep sleep. As for the depth of heterogeneous sleep, it is difficult to judge, because it is not only manifested in the relaxation of muscle tension, but also often turns over all over, and the muscles of the face and fingers twitch. In terms of feeling, it is difficult to wake up the sleeper by external stimuli, but it is easy to wake up when the stimuli have special significance or are related to the content of his dreams. These contradictions show that during heterogeneous sleep, an active process in the brain can cut off its connection with external stimuli. If judged by the activity of autonomic nervous system, heterogeneous sleep is closer to awakening state. If the sleeping person is woken up at this time, he will say that he is sleeping. On the other hand, waking him up in the slow wave stage means that he doesn't sleep well. It is speculated that this subjective sleep consciousness may be related to his dreams. To sum up, it is difficult to accurately measure the depth of sleep, and the current trend is to regard out-of-phase and slow-wave phase as two independent States.
Some autonomic nervous activities change with the development of sleep process, and there seems to be little correlation between them. For example, the body temperature gradually drops from sleep, reaches the lowest point in 5-6 hours, and then gradually rises. It has been suggested that oral materials can still be learned during sleep, but the analysis of EEG proves that sleepers are actually in a hazy state. Sleepwalking mostly occurs in the second stage of slow-wave sleep, while sleepwalking occurs in the fourth stage of slow-wave sleep without exception, both of which are generally irrelevant to the content of the dream.
Individually, newborns sleep 16 hours a day on average, and the sleep time of infants is gradually shortened, and they sleep about 9 ~ 12 hours at the age of 2. The sleep time of adults varies from person to person, generally ranging from 6 to 9 hours, and it is generally considered that 7 and a half hours is appropriate. But old people usually only sleep for six hours. According to EEG analysis, the heterogeneous sleep of newborns accounts for about 50% of the total sleep time, and soon enters the heterogeneous period after falling asleep, accounting for about 20% of adults and less than 20% of the elderly. In adults, those who sleep less than 15% or more than 25% are considered abnormal. Similarly, the fourth phase of slow wave phase decreases with age. As for the cycle of sleep and awakening, newborns sleep about 5-6 times a day, infants gradually decrease, and school-age children sleep about 1-2 times a day. Some old people have returned to the habit of sleeping several times a day. The change of the above sleep with age may be related to individual development, especially the development of the brain awakening system, and also to the needs of family, school environment and social activities. In mammals, with the development of the brain, the maturity of sleep is different. For example, newborn kittens almost have heterogeneous sleep on the first day 1 day, and they begin to have slow-wave sleep the next day, which is close to the sleep type of adult cats one month later; Almost all rats were in heterogeneous sleep within two weeks after birth, and the heterogeneous sleep was shortened to 10% after one month. Heterophasic sleep in newborn guinea pigs was less than 10%, and then it developed rapidly to less than 5%.
According to the above three characteristics of sleep: periodicity, spontaneity and reversibility, sleep behavior and EEG changes began to appear in higher vertebrates with animal quietness and decreased sensory sensitivity as measurement indicators. In fish, amphibians and reptiles, the cycle transition between awakening and sleep can be observed, but it is no different from sleep. Only warm-blooded animals and birds have obvious heterogeneous sleep, accounting for about 3 ~ 5% of sleep time. Mammals, from mice to elephants, have clear slow-wave phase and heterogeneous sleep, but their respective proportions vary from species to species. From the point of view of animal survival competition, it can be roughly divided into two categories: one is hunted animals, such as rodents, herbivores and ruminants, which need to chew for a long time after eating, so the sleep time is shortened, and the heterogeneous sleep is also short, generally less than 5%, such as cows, which is 1.6%, and anteaters actually have no heterogeneous sleep; The other is carnivores, such as carnivores. They eat fast, sleep more, and sleep longer at different stages, up to 20% or more, such as cats and dogs.
Sleep deprivation is a feasible method to study the physiological significance and necessity of sleep.
After 24 ~ 48 hours of complete sleep deprivation, the frequency of EEG slowed down, similar to 1 phase of slow wave phase, but its appearance and behavior were normal. If you continue to be deprived, your alertness will be reduced, and serious hallucinations, delirium or dreams will occur. After 3 ~ 4 days, let him sleep. On the first night, the slow wave in the fourth stage increased obviously, while the heterogeneous sleep decreased accordingly. In the next few nights, heterogeneous sleep increased compensation. A young man who didn't sleep for 1 1 day obviously increased the fourth phase slow wave and heterogeneous sleep after falling asleep. On the contrary, on the night of 1, sleep-deprived cats increased heterogeneous sleep instead of fourth-phase slow-wave sleep.
Deprived of some sleep, the subjects only slept for 3-4 hours a day. After a few days, heterogeneous sleep or scores are more than 4 hours before normal sleep. After stopping the experiment, the subjects experienced several heterogeneous sleeps for several consecutive nights. In the long-term subjects who sleep only 4 hours a day, the slow wave increases in the fourth stage and decreases in the third stage. In the process of restoring sleep, the slow wave phase has no obvious change. If the subject's sleep is shortened to less than 3 hours, it will affect the development of sleep in the fourth stage, thus seriously affecting the subject's work ability.
If you choose to deprive the fourth phase of slow-wave sleep, you will only increase the fourth phase sleep during the recovery process; If you choose to deprive heterogeneous sleep, the same compensation will be produced. Many psychological experiments show that long-term deprivation of heterogeneous sleep will not produce obvious psychological obstacles; People who have been deprived of all sleep for a long time cannot work long hours, otherwise they will make more mistakes. This may be related to the inability of the cerebral cortex to remain alert for a long time. In addition, a few people will have temporary hallucinations and absurd behaviors. In a word, these experimental results do not seem to support the hypothesis that long-term insomnia or severe insomnia will lead to psychopathy, but on the other hand, it shows that long-term lack of sleep can easily lead to fatigue, inattention and visual and tactile confusion.
Morbid sleep insomnia can be divided into three types according to the chronological order of insomnia. (1) occurs in the early stage of sleep, manifested as difficulty in falling asleep, and is also the most common insomnia. (2) The performance is waking up all night. ③ It happened at the end of sleep, and the patient woke up too early to fall asleep again. This kind of patients have less heterogeneous sleep and are easy to induce EEG wake-up response. From the EEG analysis, they always sleep much more than the chief complaint, and the consequences of insomnia are not serious. People who suffer from insomnia for a long time sometimes feel depressed and can be corrected by medication.
Polysomnia is characterized by excessive sleep or drowsiness during the day or excessive sleep at night. The patient's heart rate did not slow down during sleep, indicating that the patient did not have enough rest during sleep. Primary sleepiness is mostly genetic disease, which is related to hypothalamic dysfunction. In addition, there is a kind of narcolepsy, accompanied by overeating, obesity and lack of breathing.
When narcolepsy attacks, the patient suddenly falls asleep, which can't be controlled, only lasts for a few seconds to a few minutes, and is often accompanied by cataplexy caused by loss of muscle tension. The brain waves during the attack are similar to those during heterogeneous sleep, and most of them are congenital. Central stimulants can relieve its symptoms.
Sleepwalking occurs in the third and fourth stages of slow-wave sleep, and it is also the period with the lowest recall ability. It has nothing to do with the patient's dream. When sleepwalking, the alertness and reactivity of the brain are reduced and the movements are uncoordinated.
Enuresis mostly occurs in the first 1/3 stage of sleep, and brain waves are in the fourth stage of slow wave. Start with enuresis and go to stage 2 or 1. After waking up, the patient doesn't complain about dreams. If he doesn't wake up, there won't be three or four brain waves in a few hours. Enuresis can be treated with drugs or other methods.
The mechanism of sleeping eyes. Pavlov observed that dogs would fall asleep naturally in the unreinforced conditioned reflex experiment, so he put forward the theory that the internal inhibition process spread to the cerebral cortex and subcortical structures to produce sleep. However, the subsequent experimental research failed to provide more clear supporting arguments. 1949, Italian G. Moruzzi and American H.W. Magoun discovered that the ascending reticular tongue stimulation system in the midbrain is an important structure to produce the awakening state of the brain, and then assumed that sleep was only the result of the temporary interruption of awakening activities, and fatigue was the important reason for the interruption. The viewpoint that sleep is a passive process is consistent with the experimental results of sleep state caused by cutting off the afferent fibers of midbrain or sensory nerve. Long-term accumulated neurophysiological experimental data show that local electrical stimulation of some structures in animal hypothalamus or brain stem can cause sleep. Later, people found that the body was in an excited state during heterogeneous sleep, which indicated that sleep was an active activity process, and put forward the view that there was a "sleep center". Since the 1960s, people have done a lot of experimental research. Moruzzi and others put forward the hypothesis that there is a sleep center at the tail of brain stem. They believe that there is an ascending inhibitory system in the medulla oblongata and pons, and the activity of this system can lead to sleep. On the one hand, this system receives sensory afferent impulses from the body and viscera, on the other hand, it is controlled by the structure of piriform cortex, cingulate gyrus and preoptic area of forebrain. At the same time, Wei Ru put forward the monoamine theory about the awakening-sleep cycle. He believes that the ascending noradrenergic system in front of locus coeruleus can maintain the awakening electrical activity of cerebral cortex, and the activity of acetylcholine system can complete advanced functions such as attention, learning and memory. The dopaminergic system in the substantia nigra-striatum circuit maintains the awakening behavior. As for the sleep process, the ascending 5- hydroxytryptamine system from the anterior segment of the raphe nucleus group maintains slow-wave sleep. Once the cell activity in the locus coeruleus is triggered by the middle segment nucleus group, the ascending impulse of the latter activates the electrical activity of the cerebral cortex, causing it to have fast-frequency and low-amplitude waves, while its descending impulse inhibits the spinal motor system, thus forming heterogeneous sleep. But the author did not explain how sleep began. It should be pointed out that there is no fundamental difference between these two assumptions. Because they are just arguing about the part of the brain structure related to sleep. Nowadays, a lot of work is developing in depth along these two ideas. Since 1970s, Moniere and J.R. Papenheimer have extracted polypeptide substances from sleeping rabbits and sheep's brains, respectively, and injected them into the ventricle of another animal, which can induce δ waves, similar to slow-wave sleep. This discovery opens up a new way for the study of sleep mechanism.
Sleep is extremely important for brain health. Minors generally need to have more than 8 hours of sleep, and must ensure high quality. Insufficient sleep time or poor quality will endanger life or have a bad influence on the brain, and the fatigue of the brain is difficult to recover, which will seriously affect the function of the brain. If teenagers have insufficient sleep or poor sleep quality, they should appropriately increase their sleep time, such as taking a nap in summer, and try their best to improve their sleep conditions.
According to the general view, sleep is the main way to eliminate brain fatigue. If you don't get enough sleep for a long time or the quality of sleep is too poor, it will seriously affect the function of the brain, and people who are already very smart will become confused. Many young students suffer from neurasthenia and other diseases, which are often caused by serious lack of sleep.
In short, people spend more than one third of their time in sleep. Proper good sleep can regulate physiological function and maintain the balance of nervous system, which is an important part of life. Poor sleep, lack of sleep, the next day will be wrong, brain swelling, general weakness. Sleep is closely related to healthy work and study.
The following aspects can improve sleep quality:
There is no specific method to improve the quality of sleep. The study found that there are four factors that have great influence on sleep quality. "What four factors?" . It is the sleeping equipment, sleeping posture, sleeping time and sleeping environment.
Sleep anecdote
Crocodiles are the only animals that don't sleep.
Punishment "Don't sleep" A man was sentenced to death by King Louis XV of France, and the method of execution was not to sleep. I heard that this is an extremely severe punishment!
In Niu Yi, sleeping for two or three hours every day is enough.
Bats sleep upside down.
[Edit this paragraph] What exactly is "healthy sleep"?
● Modern media constantly publicize that it is best to sleep from 22: 00 to 23: 00. The reason is: 12: 00 to 3: 00 pm is a deep sleep period. As long as you sleep well for three hours, you will be full of energy all day. If you miss it, it will have a very bad effect on your body. It usually takes 30-60 minutes from falling asleep to entering deep sleep, so it is best to sleep at 10: 00- 10: 30 at night.
However, such "observation" is relatively "one-sided". This is because the "observer" observes on the premise of "sleeping at night".
So what is the "fact"? Let's take a look at the "reality": workers who work at night in cities, especially "night drivers", all work at night and sleep in the morning. If the above findings are correct, then all those who work at night will die, or at least be infected with various "diseases". However, they are all alive and well, which is the best evidence.
And the difference between "day" and "night" is really small in modern society, because if you fly to "America" at night in China, but it is "day" there, will we sleep or not? And we all have "electric lights" and spend most of our time indoors.
So what is the body's default "biological clock"? How can we achieve the "optimal distribution" of "work" and "rest" time?
You only need to do a small experiment to know that when you watch a soap opera all night, you will start to "sleep" at 6 am, and finally you will "wake up" naturally from 12 to 14 in the afternoon. At this time, just count the sleep time and you will know that it is exactly 6-8 hours. Do you think it was an accident? Why doesn't it follow your long-standing 7-9 "get up" time?
● That is to say, the default "sleep time" of "biological clock" is "wake up" 6-8 hours after sleep; And when to "sleep" is not the most important. As long as you "sleep", those "physiological activities" that will happen after sleeping will still be carried out, or: as long as you have enough "sleep time", no matter when you start sleeping, it will not affect your "health"; "Work and rest time" is just a "habit" and can be changed at will. Of course, it takes some time to form a new habit, usually 3-6 days, so it is best not to alternate this habit too often.
Only in this way can everyone "feel at ease" to carry out all kinds of "overtime" or "night shift" activities, otherwise there will always be certain "psychological obstacles", which is not good.
● Excerpted from The Complete Works of Civilization X Files.
[Edit this paragraph] Other judgments about the best sleep time
General sleep time:
1. Normal people sleep for 8- 10 hours.
2. The time for beauty sleep is 10- 2 am.
3. Stay up late for a long time ... Even if you sleep for 8 hours, you will be prone to endocrine disorders in a few years and your biological clock will go wrong.
Children had better go to bed before 8: 30 in the evening, because they need biological clocks when they grow up.
Teenagers should go to bed around 10:00 at night.
6. As for people who love beauty, they should go to bed before 2:00 a.m. (preferably before 65438+ 02:00 midnight) because the skin is metabolized before 2:00 a.m..
7. Old people should sleep between 9: 00- 10: 00 in the evening.
Also: you must go to bed at 12:00 at night. Everyone has a physiological clock in his body, which shoulders different physiological tasks at different times. Don't ignore it easily!
The biological clock says:
1.00: 00-0 1: 00 shallow sleep period-dreamy and sensitive, people who are unwell are likely to wake up at this time.
2.0 1: 00-02: 00 Detoxification period-At this time, the liver is actively eliminating toxins, so it is necessary to put the body to sleep before the liver can complete the function of metabolizing waste.
3.03: 00-04: 00 Hibernation period-the most vulnerable moment for critically ill patients, and patients often die at this time. It is best not to stay up late beyond this time.
4.09: 00- 1 1: 00 essence period-this is the best time for attention and memory, and also the best time for work and study.
5. 12: 00- 13: 00 lunch break-it is best to sit still or close your eyes before eating. Don't drink at noon, it's easy to get drunk and hurt your liver!
6. The peak period 14:00- 15:00- is the time when analytical power and creativity can be brought into full play!
7. 16: 00- 17: 00 low tide-the stage of weak physical consumption, it is best to supplement fruits to relieve hunger and avoid overeating leading to obesity.
8. 17: 00- 18: 00 relaxation period-at this time, blood sugar rises slightly, and the sense of smell and taste is the most sensitive. Dinner should be prepared to boost your spirits.
9. 19:00-20:00- It is best to take a walk or take a bath 30 minutes after meals to relax and relieve the fatigue of the day.
10.20: 00-22: 00-this is the peak time of evening activities, so I suggest you make good use of this time to discuss, study and other activities that need careful consideration.
1 1.23: 00-24: 00 Night sleep period-after a busy day in the city, you should relax and fall asleep at this time. Don't overload your body, it's not worth the loss!