Sleep principle

Sleep is the best way to quickly recover physical strength, cultivate essence and refresh your mind, but good sleep quality is based on the principle of sleep.

Sleep is a common phenomenon in animals with wet infiltration and scaly shells. The degree of sleep is closely related to the brain. Just like a computer, it has a sleep mode and needs to be turned off and rested. Closing the program reduces the burden on the processor and enables the processor to recover after a high level of work.

Sleep is divided into three stages, prophase, metaphase and anaphase. The early stage is the preparation for going to sleep, the middle stage is the state of rapid recovery, and the late stage is the state of slow repair. For example, after the spring is released, it contracts quickly first, and then contracts to the extent that it is invisible to the naked eye. This is a repair process, which can enhance the service life and maintain the effect.

Therefore, sleep must be of good quality and have enough time to maintain a good state, which is also the key to health.

Sleep is a self-protection mechanism, and waking up from sleep is also a protection mechanism. Good sleep is the most important thing for health and survival.

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The difference of sleep between mammals and other creatures.

There are three main types: form, period and time.

In nature, from insects, fish, birds and animals to all kinds of mammals, there are unique forms of sleep, even plants, and some people say that they sleep in the form of seeds. "Summer sleep" is the sleep form of some marine creatures, and "hibernation" is the sleep form of toads and snakes. However, sleep in mammals occurs alternately in non-rapid eye movement period and rapid eye movement period, which is different from other creatures' sleep cycle.

Different creatures, different species, different sleeping conditions. Bats and opossums can sleep 18-20 hours a day, while elephants and giraffes only need 3-4 hours. In fact, there are also differences in relative teaching between the same species. For primates, there is no unique sleep pattern that can be distinguished from rodents, insectivores and other species, but compared with other omnivores, human sleep time is relatively short.

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Can people not sleep? What happens if you don't sleep for a long time?

Peter Tripp, an American, took part in an experiment without sleeping for 200 hours.

For the first three days, everything was fine. From the fourth day, I began to have a nervous breakdown, laughing at some funny things and unable to control myself. Some sad news also cried inexplicably; Originally, I didn't wear a hat, but I always complained that the hat on my head was too heavy.

On the fifth day, the subjects shouted hysterically. One minute they say other people's coats are like crawling bugs, and the next they say they ran out of the burning room. After 200 hours, he was tortured like a mental illness, almost crazy. I slept for 9 hours when I was put to bed, and returned to normal after 1 1 minute. Obviously, it is impossible for people not to sleep.

Sleep accounts for 1/3 of human life cycle, and sleep quality is the basis of quality of life. Long-term lack of sleep may lead to short-term hallucinations and abnormal behavior.

Sleep is the best way to recover physical strength, brain power, fatigue and self-recovery, and it can also maintain and enhance the immune function of the human body. If a person loses four hours of sleep, the activity of immune cells that resist foreign bacteria will be greatly weakened the next day.

Sleep is a physiological need and mainly consumes energy during the day. At night, energy consumption is greatly reduced, and energy storage is greater than consumption, so as to prepare for the next day's activities.

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Sleep cycle

People's normal sleep state consists of alternating non-rapid eye movement period and rapid eye movement period, and non-active sleep, that is, NREM sleep period. It is manifested as the sleep performance of brain waves, and the muscle activity is weakened when awake, and there is no severe eye movement. Active sleep, that is, rapid eye movement sleep stage, is still a sleep stage, but it is essentially different from NREM sleep stage. From most indicators, the state of brain activity during REM sleep is similar to that during waking.

People enter the NREM sleep period from going to bed. Sleep is divided into four stages, and the last two stages are called deep sleep. The NREM sleep period lasts about 70 ~ 90 minutes, and enters the first REM sleep period. The intensity of physiological performance (rapid eye movement) and psychological performance (dreaming) is the weakest in every REM sleep period overnight. Generally, it only lasts about 5 minutes, and each time REM sleep is gradually prolonged, the physiological and psychological manifestations of REM sleep are becoming more and more obvious. REM sleep occurs 4-6 times a night, and the duration of each time is 10 minute or 1 hour.

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How does EEG change during sleep?

Sleep and awakening are different physiological States, and their EEG is also different. Sleep consists of non-rapid eye movement (NREM) and rapid eye movement (REM).

The stage of sleep is determined by combining the characteristics of brain waves and other physiological manifestations. First of all, according to the characteristics of brain waves, inactive sleep is usually divided into four different periods from shallow to deep:

In the first stage, low-voltage brain waves appear, and the frequencies of the waves are mixed, mainly 4-7 times/second.

In the second stage, low-voltage brain waves are dominant, with short-term serial sleep spindle waves and top hump waves of 12- 14 times per second, representing the shallow sleep process.

In the third stage, brain waves are mainly sleep fusiform waves, which is one of the important signs of sleep. There are often short-term slow waves with medium and high amplitude, the amplitude is greater than 50 microvolts, and the frequency is 1-2 times per second, which is called δ wave.

In the fourth stage, there are 0.5-3 times of high-amplitude diffuse irregular slow waves per second, accounting for more than 50% of the total time, indicating that it has entered a deep sleep state.

It can be seen that during NREM sleep, with the gradual deepening of sleep, the slow waves of EEG begin to appear and gradually increase, and when δ waves dominate, it is deep sleep.

Unlike NREM sleep, REM 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.

In addition, there are differences in other physiological indexes between the two sleep cycles.

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.

In REM phase, autonomic nervous system activities are enhanced, such as increased heart rate, accelerated breathing, increased blood pressure, increased cerebral blood flow and oxygen consumption, while male patients have erection of the vagina. Like animals, rapid eye movement in humans has three characteristics:

The effects of these two sleep periods are very different. It is found that non-REM sleep is mainly used to restore physical strength, while REM sleep is mainly used to restore brain power. Physiological indexes such as EEG are important signs to identify sleep stages.

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The relationship between sleep and seasons

Changes in different environments and seasons will also affect sleep time to some extent.

Sun Simiao said in "Fang Volume 27: Preface to Cultivating Sexuality", "Those who are good at cultivating themselves will lie down from four o'clock in the morning and evening and live in harmony." It is said in the same volume "Cultivating Nature in Daolin" that "it is beneficial to people to lie down and get up early in spring, lie down and get up early in summer and autumn, and lie down and get up early in winter. Although the cloud gets up early, don't crow before the cock; Although you want to get up, you can't get up after sunrise. " The central meaning of this passage is to tell people that the morning and evening of going to bed and getting up should adapt to the changes of the four seasons' climate, neither too early nor too late, otherwise it will have a bad influence on their health. ?

According to the theory of traditional Chinese medicine, it is advisable to go to bed late and get up early in spring and summer, and sleep for 5 to 7 hours every day; It is advisable to go to bed early and get up early in autumn, and sleep for 7-8 hours every day; It is advisable to go to bed early and get up late in winter, and you need to sleep for 8 ~ 9 hours every day. This conforms to the laws of nature.

In addition, on sunny and hot days, sleep time is short; In bad weather, such as rainy days and low temperature winter, sleep for a long time; With the increase of regional altitude, the sleep time decreases slightly; With the increase of latitude, the sleep time is slightly prolonged.

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Relationship between sleep and biological clock

Researchers at the Biological Rhythm Laboratory of Chicago Medical Center in the United States pointed out that sleeping late on weekends is not good for most people, because it will make the body's biological clock disorder, delay sleep time, make it difficult to fall asleep on Sunday night, and feel groggy on Monday morning, and this disorder will even take several days to return to normal.

Due to the change of human biological clock, the functions of different areas of cerebral cortex also change from time to time. The research results show that:

8 ~ 1 1 am is the best time to organize, plan, write and carry out some creative thinking activities. It's best to finish the most difficult task of the day at this time. At the same time, the pain is the least sensitive at this time, and it is most appropriate to see a dentist at this time.

1 1 ~ 12 The early morning is the best time for a meeting, when people are most awake. It's easy to solve problems and make some complicated decisions during this time.

12: 00- 2:00 pm, the joyful mood reaches its climax during the day, which is suitable for business and social activities.

From 2 pm to 4 pm, there will be a so-called "afternoon depression period". It's easy to get sleepy at this time. It is best to take a nap, or make some necessary phone calls, do some interesting reading, and try to avoid boring activities.

At 4 ~ 6 pm, the human body was freed from the "trough period" and its thinking became active again. At this time, you can do the more important work of the day. And this is a good time for long-term memory.

From 5 to 7 pm, the temperature of the human body is the highest, so doing some exercise at this time will help you fall asleep smoothly at night and improve the quality of sleep.

7 ~ 10 in the evening can discuss some serious family topics, which is also the best time to study.

At night 1 1 ~ 12, the human body is ready to rest, and the activities of various organs are extremely slow, so it falls asleep.

Can changing the time of falling asleep and getting up affect people's mood? Researchers in the United States and Britain have found that people's mood is not only affected by the length of sleep, but also has a great relationship with whether they arrange sleep and get up according to biological rhythm.

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Endocrine changes during sleep

Sleep plays an important regulatory role in many aspects of endocrine system. During sleep, the secretion of growth hormone and prolactin increased significantly, while the release of cortisol and thyrotropin was inhibited. On the contrary, waking from sleep will inhibit the secretion of growth hormone and prolactin at night, accompanied by the increase of cortisol and thyrotropin concentrations. The gonadal axis is also affected by sleep, and sex hormones also affect the quality of sleep. The influence of sleep on endocrine is not limited to hypothalamus-pituitary axis, but also affects many hormones involved in carbohydrate metabolism, appetite regulation and maintaining water and electricity balance. Therefore, poor sleep will cause hormone secretion disorder and metabolic disorder. With the increase of age, some hormonal disorders and metabolic disorders are the manifestations of the decline of sleep quality. Therefore, improving sleep quality is beneficial to the stability of endocrine and metabolic system functions.

Let's take a look at how various hormones change during sleep and what is the relationship with sleep.

The relationship between sleep and growth hormone;

Its secretion is stable, almost unchanged during awakening, but it rises sharply after falling asleep for 30-40 minutes and reaches its peak after 90-100 minutes. Usually, in the initial non-active sleep M and IV stages, the peak state has obviously appeared, and then it slowly declines. When it entered the stage III and IV of the second passive sleep, the secretion increased again, showing a biphasic peak.

In the third and fourth stages of the sleep cycle of passive sleep, the secretion of growth hormone no longer rises, which is one of its characteristics. Another feature is that if the sleep time is delayed, that is, if you sleep late, the increase of growth hormone secretion will also be delayed, which is always synchronized with the increase of ⅲ and ⅳ stages of the previous two inactive sleep. It can be seen from the above facts that the secretion of growth hormone does not follow the 24-hour cycle law, but is regulated by sleep.

The secretion of growth hormone is also related to age and sex. The secretion of newborns is in a vigorous state during the whole sleep period, and there is no such increase and peak of secretion. The biphasic peak of secretion curve appeared after 16 weeks. In adolescence, the secretion of growth hormone increases more than any age group during sleep, and it also increases more than any age group during awakening. The secretion of growth hormone in adolescence is about 7.5 times that before this period, and it is also much higher than that of adults. After the age of 50, the secretion of growth hormone is obviously reduced, and it is difficult to detect growth hormone even during sleep.

From the perspective of gender, the general trend is that women secrete more than men during the whole time of sleep and awakening.

The relationship between sleep and prolactin;

Its secretion in the awakening state is low, with little fluctuation. After falling asleep for 60 minutes, it began to increase slowly and reached a peak at 6-8 am the next morning. Once you wake up, the secretion decreases sharply until around 10 in the morning, and then it remains at a low level. Not only sleep at night, but also the release of prolactin will increase when the nap and sleep time change during the day. The release of prolactin can only reach its peak when sleep and circadian rhythm are consistent, and women are much higher than men. Animal experiments have found that prolactin is controlled by rapid eye movement sleep. This shows that the 24-hour rhythm of prolactin is closely related to sleep.

Some commonly used hypnotics, such as benzodiazepines and pyrazoletan, will increase the release of prolactin at night, exceeding the normal high limit.

The relationship between sleep and gonadal axis;

The relationship between gonadotropins and sex hormones varies with different stages of growth and development, and there are also great differences among young people due to gender differences.

Before puberty, luteinizing hormone and follicle stimulating hormone are secreted in the form of pulses, and the increase of hormone pulse activity in most boys and girls is related to sleep. The increase of gonadotropin during sleep is a characteristic of adolescence. In other words, sleep and circadian rhythm play an important role in the increase of gonadotropin secretion in adolescents at night. The diurnal variation of estradiol level in adolescent girls is more obvious, and the daytime concentration is higher than that at night. The secretion of testosterone and gonadotropin in adolescent boys increased synchronously at night.

In adulthood, the daytime pulse secretion also increases, but the daily secretion rhythm disappears. The diurnal variation of luteinizing hormone in the blood of adult men is very weak, even undetectable. For healthy men, the concentration of prolactin at night still has a circadian rhythm, that is, the lowest at night and the highest in the morning. The level of luteinizing hormone in adult women's blood is influenced by menstrual cycle and not regulated by sleep.

The pulse secretion amplitude of luteinizing hormone in elderly men decreased, the frequency increased, and there was no obvious daily rhythm. But the rhythm of testosterone still exists, and the increase of sleep-related testosterone secretion is still obvious. The level of gonadotropin in postmenopausal women increased, but lost its original rhythm. Studies have confirmed that estrogen replacement therapy can improve subjective and objective sleep quality.

Relationship between sleep and thyroid axis function;

Thyroxine concentration is low and stable during the day, rising at night, and reaching the highest value at night soon after falling asleep. Thyroid hormone secretion is greatly reduced in the late stage of sleep, and it maintains the level after waking up in the morning during the day. 24-hour thyroxine secretion follows the typical daily I-division law. However, during sleep deprivation, the secretion of thyroxine is twice as normal, and the influence of sleep on thyroxine secretion is fully reflected, that is, sleep can inhibit thyroid secretion, and sleep deprivation can relieve this inhibition.

The inhibitory effect of sleep on thyroxine secretion is time-dependent, so the increase of thyroxine is the result of the interaction between sleep and circadian rhythm Studies have proved that the subjective discomfort and fatigue of some patients with jet lag syndrome are related to the disruption of the circadian rhythm and the continuous increase of hormone levels in the blood.

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Relationship between sleep and adrenocorticotropic hormone axis;

As we all know, corticotropin axis is related to the neuroendocrine system related to stress response and behavior. Two important hormones in the corticotropin axis are corticotropin and cortisol. With the passage of time, the levels of these two hormones gradually decreased from the peak in the morning to the lowest from late at night to early morning. Usually, when people fall asleep, the axis of adrenocorticotropic hormone tends to be static, while the secretion of adrenocorticotropic hormone and cortisol begins to be active a few hours before waking up. This change is mainly controlled by the circadian rhythm, and is not obviously affected by not sleeping or not sleeping at the appointed time.

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However, some abnormal sleep conditions will interfere with its secretion. For example, during sleep deprivation, the effect of sleep or awakening on ACTH axis activity disappears. It was found that the fluctuation range of cortisol after sleep deprivation decreased by about 15%j In addition, many studies showed that sleep interruption often triggered cortisol secretion. A survey of insomniacs shows that when the total sleep time at night is reduced, the blood cortisol concentration will be higher. It is not clear whether the decrease of sleep leads to the increase of cortisol or the increase of cortisol leads to the interruption of sleep, but it is certain that sleep awakening can regulate cortisol.

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Regulation of sleep on blood sugar level;

Many studies have found that after 7-9 hours of fasting sleep, blood sugar levels remain stable or only slightly decrease. On the other hand, if an individual stays on an empty stomach for more than 12 hours while awake, his blood sugar will drop by 0.5 N 1.0 mmol/L even though there is no physical activity. Therefore, there must be a series of mechanisms to maintain the stable state of fasting blood sugar during sleep. Studies have found that many hormones in sleep, such as growth hormone, cortisol and insulin, are involved in the process of glucose metabolism. Of course, if there is a problem with sleep, there will be a problem with hormone levels, and then the blood sugar level will be abnormal at night.

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Regulation of hormones on water and salt balance in sleep;

Water and salt balance is regulated by neurohypophysis and renin-angiotensin aldosterone system. Urine flow and electrolyte excretion are more during the day than at night, reflecting the regulation of circadian rhythm. In addition to the 24-hour circadian rhythm, urine flow and urine osmotic pressure will also change with the transition from active sleep to inactive sleep. The urine flow of active sleep decreased and the urine osmotic pressure increased. At the same time, plasma renin activity also decreased. If the sleep structure is abnormal, it will also lead to the abnormality of various hormones and affect the change of urine volume:

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The effect of sleep on appetite;

Sleep plays an important role in regulating energy balance. In rodents, food shortage or hunger can lead to lack of sleep, which can also lead to overeating. This regulatory mechanism occurs in hypothalamus, in which leptin and brain-gut peptide play an important regulatory role, and their roles are diametrically opposite: leptin is secreted by adipocytes, which can provide energy utilization information for the regulatory center of hypothalamus. During the 24-hour rhythm, the leptin level at night increased significantly. The level of leptin in narcolepsy patients decreased obviously, and the secretion of leptin did not increase at night. Brain-gut peptide is mainly produced in the stomach and also participates in the regulation of energy balance. Unlike leptin, brain-gut peptide can increase appetite. In the 24-hour rhythm, the nighttime level is obviously increased, and it will be partially reduced as long as it is sleep deprivation. Their opposite effects maintain the energy balance of the human body.

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Effect of long-term sleep deprivation on endocrine;

Since the invention of electric light, people have invisibly extended the time of illumination, shortened the time of sleep and obviously increased the time of people's activities. 24-hour bright lights have also caused thousands of people to work at night and sleep during the day, which will undoubtedly cause insufficient sleep. Active shortening of sleep time has become a common problem in modern Shi Feng Expo. Studies have shown that many adults only sleep 5-6 hours every night, but they don't know that 8 hours of sleep can't meet the needs of healthy young people at all. Even if the reduction of sleep time has no obvious adverse effects, it has actually owed sleep debt.

One is a study of young men. Sleeping for 6 hours every night for 6 days, sleeping for 12 hours, found the following changes.

The secretion of growth hormone in patients with long-term sleep deprivation begins before sleep, and the secretion before sleep is negatively correlated with the secretion after sleep. The change of cortisol is that lack of sleep will lead to 24-hour concentration fluctuation. Lack of sleep will greatly reduce the increase of thyroxine at night, and the 24-hour average concentration will drop by 30%. Compared with people who sleep 12 hours a night, people who sleep for 6 hours a night will have higher blood sugar levels after breakfast, while people who repeatedly lack sleep will have lower glucose tolerance after eating sugary breakfast. The daily average level, peak value and fluctuation range of F leptin will be reduced by 20% ~ 30% in people with insufficient sleep, which is equivalent to the effect of 900 kilocalories a day for young people with normal sleep. In addition, the study of human beings also shows that after the sleep time is reduced, the leptin level decreases and the brain-gut peptide level increases, which makes people hungry easily and thus makes them gain weight.

In short, sleep is closely related to the levels of various hormones in the human body. This also explains why sleep is so important to all organs and systems of the human body.

Think about three meals a day and one night at night. Adequate sleep is essential, water is flowing, haste makes waste, and paying attention to sleep is to care for health.