More than 300 million people in the country suffer from sleep disorders. How can we get a good night's sleep?

One-third of a person's life is spent sleeping. High-quality sleep is an intangible wealth, and people's demand for sleep is increasing. On March 21, another "World Sleep Day" is coming. According to the "2021 Exercise and Sleep White Paper" released by the China Sleep Research Society in Beijing, more than 300 million people in China have sleep disorders. What are the manifestations of sleep disorders? What can we do to get a good night's sleep?

In this issue of Capital Science Lecture "Minimal Science Class", we invited Guo Xiheng, director of the Respiratory Sleep Center and chief physician of Beijing Chaoyang Hospital affiliated to Capital Medical University, to authoritatively analyze sleep problems and show you how to ensure healthy sleep, how to overcome sleep disorders and improve sleep quality.

Compiled by reporter Zhao Ling Edited by Ji Jingjing

New Media Editor/Chen Xuanzhi

【Keynote Speakers】

Guo Xiheng

Director and Chief Physician of the Respiratory and Sleep Center of Beijing Chaoyang Hospital, Capital Medical University

Director of China Sleep Research Society

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What is sleep?

Sleep is a natural resting state that is common in mammals, birds, fish and other organisms. This resting state is the prerequisite for the survival of organisms. During the sleep process, awakening will definitely occur, which is a protective mechanism to ensure health and survival.

The sleeping behavior of different species is very different. For example, on the African savannah, lions often sleep in a very random position, lying horizontally or vertically, because they are at the top of the food chain and are very confident in their living environment, facing little threat and having a high sense of security. On the contrary, antelopes sleep very little, because if they sleep for a long time, they may be captured by carnivores. This reminds us that if we feel safe, comfortable and happy, then we may sleep better; if we feel nervous, anxious and lack a sense of security, then it may affect our sleep and make it difficult to fall asleep.

Generally speaking, sleep has three characteristics: periodicity, spontaneity, and reversibility. Periodicity is easy to understand, working during the day and sleeping at night, and sleep behavior occurs repeatedly. Spontaneity means that we do not need to make special efforts to fall asleep. As long as the timing is right and there is a relatively safe and comfortable environment, we can fall asleep. This is a natural process. Reversibility means that after sufficient sleep, we will wake up naturally, and this awakening process is inevitable.

There are large differences in the sleep time of different species, which is closely related to their physiological needs. For example, a normal adult sleeps for 7 to 8 hours, which is the time required by physiology. However, some livestock, such as cows, sleep for a relatively short time. For example, mice actually sleep for a long time, but they sleep during the day and come out to move at night.

Through the monitoring of sleep EEG, we found that sleep can be divided into two forms: non-rapid eye movement sleep (NREM) and rapid eye movement sleep (REM), and non-rapid eye movement sleep can be divided into stages 1, 2, and 3. In layman's terms, the so-called rapid eye movement sleep means that you often dream during sleep; and non-rapid eye movement sleep means that you rarely dream during sleep. This type of sleep can also be divided into light sleep and deep sleep. High-quality sleep requires a certain time and proportion of deep sleep and rapid eye movement sleep.

A complete sleep cycle should include these processes: first enter light sleep, then from light sleep to deep sleep, then from deep sleep to light sleep, and then transition to REM sleep with dreams. The sleep cycle of a normal adult is about 90 minutes, and a night of 7-8 hours of sleep will go through 4-5 sleep cycles. Children's sleep cycle is relatively short, about 60 minutes.

Generally speaking, during a night's sleep, as time goes by, the proportion of deep sleep gradually decreases, while the proportion of REM sleep continues to increase. Since high-quality sleep is determined by both deep sleep and REM sleep, a full night of sleep is important for healthy humans. No matter which part of sleep is ignored, it is not a complete and healthy sleep.

People of different ages have very different sleep characteristics. Babies sleep most of the time, and the time can be very long, up to more than ten hours, or even twenty hours. As the child grows older, his (her) sleep time is shortened, and the sleep pattern has also changed a lot. After growing up, their sleep time is concentrated in the evening. When they reach the elderly stage, they often wake up easily during sleep at night, and often take naps during the day. The sleep pattern at this time is actually similar to that of children, but the quality of sleep cannot return to the state of children. The proportion of rapid eye movement sleep and deep sleep is decreasing, so it is easy to wake up.

In general, sleep can eliminate fatigue and restore physical strength; protect the brain and consolidate memory; enhance immunity and rehabilitate the body; promote growth and development; delay aging and promote longevity, and it deserves everyone's serious attention.

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Why do we need regular sleep patterns?

Since sleep can eliminate fatigue, is it okay to sleep when you feel sleepy? Why does sleep need to be regular?

This starts with the mechanism of sleep. The mental changes of the human body are cyclical. For example, in the morning, you are full of energy and in good condition, but in the evening you feel sleepy and have low work and study efficiency. This can be seen from the changes in body temperature: before we go to bed at night, our body temperature will be relatively high. After falling asleep, the body temperature will gradually drop, and the sleep state will gradually enter deep sleep. In the second half of the night, the body temperature gradually rises again, and the brain and body also undergo some corresponding changes. In the morning, the brain will wake up, and then there will be a process of awakening. For humans, the cyclical changes in body temperature every day are closely related to the occurrence and end of sleep, and the degree of wakefulness of the brain also changes with this cycle.

In addition, there are many other elements that undergo periodic changes in the human body, such as melatonin, cortisol, blood pressure, endocrine system, and mental state. The combined effect of these periodic changes determines the time of sleep and wakefulness. If you follow the physiological laws, it will be easier to get a better sleep, and you can also complete the physiological process of periodic changes in the body through this normal sleep process. Since the body changes according to a certain periodicity, once our sleep is irregular, it may destroy the body's periodic environment, which may affect memory, the brain's alertness function, endocrine system, etc. If these systems are disordered, it will in turn affect our sleep.

When you wake up in the morning, cortisol will be released in large quantities, and you will have a relaxing and happy day. Due to light stimulation, the secretion of melatonin is very small at this time. At night, as the light becomes weaker, the release of melatonin increases significantly, and the release of cortisol decreases, which makes us feel sleepy and want to sleep. During sleep, the effect of melatonin makes the sleep quality higher. In the second half of the night, the release level of melatonin gradually decreases. When it drops to a certain level, it triggers our awakening response.

The release of hormones in the body is invisible, but it can be seen from our behavior. If sleep is often irregular, such as sleeping at the peak of cortisol release in the morning, the secretion center in the body may adjust to increase the release of melatonin and reduce the release of cortisol when you should get up in the morning. This will cause daytime sleepiness and lack of energy to work. At night, if you do not fall asleep, but turn on the lights or mobile phones, use light to inhibit the release of melatonin, or keep the brain highly active, so that the level of cortisol cannot be reduced, this will lead to endocrine disorders.

In general, sleep is an important indicator of our biological rhythm. Regular sleep is a prerequisite for ensuring that the body's internal environment, including endocrine function, immune function, nervous system and some other systems, can remain normal.

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Is lack of sleep harmful?

German college student Randy Gardner once conducted a sleep deprivation experiment to see how long humans can last without sleep and what consequences it would bring. He did not sleep for 240 consecutive hours from December 28, 1963 to January 8, 1964. Although there were many assistants to ensure his safety during the experiment, his consciousness became blurred and some other problems occurred in the later stages of the experiment. The emergence of these unsafe signs prompted the termination of the experiment. Although people can adjust their sleep within a certain range, if they do not sleep for a long time, the human body will have many problems and even face death. Sleep is very important for physical health and life safety.

▲Randy Gardner's sleep deprivation experiment

Some people have done relatively mild experiments, such as changing the daily sleep time from 8 hours to 6 hours. After a few weeks, the person's appearance and mental state have changed greatly, with obvious signs of aging, slow reaction, confusion, decreased work and learning abilities, and unstable emotions.

▲The left picture shows a person who sleeps 6 hours a day and looks like 51 years old; the right picture shows a person who sleeps 8 hours a day and looks like 39 years old

Many people may be unfamiliar with sleep deprivation. In fact, sleep deprivation is staying up late. According to the 2020 "White Paper on Chinese Sleep during the COVID-19 Pandemic", during the period when everyone stayed at home, more than 50% of people in China went to bed after midnight. When we stay up late, due to the stimulation of ambient light, the central nervous system regulation function of the brain may be readjusted, and this readjustment process will in turn further affect our sleep.

There are two main effects of lack of sleep: one is physiological, and the other is psychological. Physiologically, lack of sleep can cause high blood pressure, decreased digestive function, decreased memory, endocrine disorders, cardiovascular disease, diabetes and other problems. Psychologically, lack of sleep can cause people to feel nervous, anxious, depressed, irritable, and easily angered.

Compared with men, lack of sleep is more harmful to women, which may cause endocrine disorders, menstrual disorders, mood disorders, obesity, stroke, and even susceptibility to tumors. Some people lack sleep and have poor sleep quality, which manifests as increasing weight. This is obesity caused by endocrine disorders.

There have always been many "folk remedies" for improving sleep, such as drinking. Although alcohol does have the effect of inducing sleep, people are different. Some people tend to want to sleep easily after drinking, while others become overly excited after drinking. And by monitoring the EEG of people who fall asleep after drinking, we found that although their sleep time is longer, the deep sleep time is very short, and the light sleep time increases significantly. Some people even wake up repeatedly, and once they wake up, it is difficult to fall asleep again. Therefore, alcohol is not good for sleep. Long-term drinking will disrupt sleep and cause various degrees of sleep disorders.

It should also be noted that the more sleep you get, the better. The normal sleep time for an adult is 7-8 hours. If you sleep too long, you may have sleep disorders, which is not good for your health.

There are many forms of sleep. For example, some people like to go to bed late and get up late. If you can fall asleep in a relatively stable time period and have a good sleep, it is also possible. Some people go to bed late and get up early. This form of sleep has a relatively short sleep time and may cause insufficient sleep. There are also people who go to bed early and get up late, which requires considering whether the individual needs such a long sleep time. If the individual is healthy and needs a long sleep time physiologically, then it is also possible. However, some people have poor sleep quality and want to improve their sleep by prolonging their sleep time. This is a manifestation of sleep disorder. It is best to go to the hospital for treatment in time.

Although sleeping habits are greatly affected by individuals, you can still judge whether your sleep is healthy from three aspects: sleep timing, sleep duration and feeling after waking up. Specifically, the best time to sleep is around 10 pm, sleep duration is 7-8 hours, and after waking up, there is no bad mental state, drowsiness, fatigue, memory loss, bad mood, etc.

If you have problems sleeping for a long time, you should go to the hospital to see a doctor and ask the doctor to analyze what kind of sleep problem you have, and then take the correct treatment. Don't deal with it arbitrarily by yourself, so as not to cause more serious sleep disorders. Taking the treatment of insomnia as an example, it is necessary to relieve clinical symptoms (shorten sleep latency, reduce the number of night awakenings, and extend total sleep time); maintain normal sleep structure; improve quality of life, improve cognitive and social interaction functions; treat concomitant diseases, and control the development of symptoms.

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Is snoring during sleep a disease?

Many people snore when they fall asleep. Some people think that snoring means a good sleep. Is this true? In fact, people who snore have very poor sleep quality and are in a state of lack of sleep for a long time. Therefore, they are not easy to wake up when they sleep and always want to sleep. People who snore in life often want to take a nap and sleep wherever they sit. And the snoring will also affect others and cause sleep disorders for others. In addition, some people will suddenly stop snoring during sleep, which is called sleep apnea. The result of respiratory arrest is a drop in blood oxygen level, which can cause a series of problems in severe cases. Therefore, snoring is actually a disease.

Regarding the quality of sleep, personal subjective judgment is often not as accurate as professional instruments. In clinical practice, more professional conclusions can be drawn by observing a series of parameters such as oral and nasal airflow breathing, chest and abdominal respiratory movements, blood oxygen saturation, electrocardiogram, body position, snoring, leg movement, etc. through professional instruments such as electroencephalogram, electromyogram, eye movement, etc.

For example, there is a patient with sleep apnea. The EEG shows that he is in a state of sleep, while the breathing waveform shows that he has stopped breathing. Sleep apnea will occur repeatedly, which will cause a decline in sleep quality. When a person wakes up repeatedly during sleep, and this awakening is too short, we call it micro-awakening. This micro-awakening is imperceptible to the snoring person, but it turns a continuous sleep process into a fragmented sleep process, causing the patient to often stay in the light sleep stage and it is difficult to enter deep sleep, which does not have the effect of relieving fatigue.

So, what causes snoring during sleep? There are two main reasons. On the one hand, there are local factors in the upper airway structure, such as problems with the nasal cavity, pharyngeal cavity, and larynx; on the other hand, there are systemic factors, such as obesity, smoking, drinking, etc.

It is worth noting that men snore more than women. This is because of the protective effect of female hormones, but this hormone will drop significantly after menopause. Therefore, women after menopause are very likely to have aggravated snoring.

So what kind of consequences will snoring and apnea during sleep have on our bodies? On the one hand, snoring will destroy our sleep structure and cause daytime sleepiness; on the other hand, it will cause patients to suffer from hypoxia, arteriosclerosis, cerebral thrombosis, cerebral hemorrhage, coronary artery sclerosis, and fat metabolism disorders and sugar metabolism disorders. Some people often snore and apnea repeatedly at night, which can cause high blood pressure at night or high blood pressure in the morning. Over time, persistent high blood pressure will occur. Some people suffer from repeated and long-term hypoxia of the nervous system, which can cause anxiety, depression, and even induce epilepsy at night. In more serious cases, it may cause sudden death at night.

For patients who snore during sleep, the specific cause must be determined, and individualized analysis and comprehensive treatment must be adopted. For example, if some patients are too obese, we encourage them to lose weight and use non-invasive ventilation; if the patient has bad living habits, such as smoking and drinking, they should pay attention to quitting smoking and drinking; some people snore and apnea are more serious when sleeping in the supine position, but there will be very obvious improvement and relief when sleeping in the side position, so adjusting the sleeping position is actually a very simple and effective method. For special patients, we can treat sleep snoring and sleep apnea through minimally invasive technology.

(Image source: Capital Science Lecture No. 685)

Produced by: Science Central Kitchen

Produced by: Beijing Science and Technology News | Science Plus Client

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