Characteristics of the slow phase of human sleep. How does deep sleep affect a person’s well-being and how long should this stage last?

For every person, the importance of a good night's sleep cannot be overestimated. This is the key to good performance the next day and healthy body. During the night, 4-5 cycles alternate, each of which includes a slow phase and a fast one. It is difficult to say which of them is more important for the body, but most scientists are inclined to believe that deep sleep is responsible for restoring many functions of the human body.

What is deep sleep

Immediately after falling asleep, the slow phase begins, which includes delta sleep. After some time, it gives way to fast, it is also called paradoxical. At this time, the person is sleeping soundly, but you can’t tell from external manifestations. You can observe movements and play different sounds.

The duration of this phase is short, but important for the body. Scientists believe that during deep sleep, maximum restoration of the body and replenishment of energy potential occurs.

During the night, the ratio of the duration of the phases changes and closer to dawn, the deep sleep phase increases the duration, and slow sleep shortens.

It has been found that under certain physiological conditions and pathologies, deep sleep increases, which signals the need for additional time for recovery. This can be observed after heavy physical work or in the presence of thyroid pathologies.

The influence of the deep sleep stage on intellectual abilities

Numerous studies involving volunteers have found that deep immersion in the world of dreams at night has an impact on physical recovery and mental abilities. Before going to bed, they were asked to remember several unrelated words. Those who spent more time in the delta sleep phase were able to remember more words, while the performance of subjects who slept less was significantly worse.

Scientists are sure that depriving a person of deep sleep is the same as not sleeping all night. The fast phase can still be compensated, but the slow phase cannot be caught up.

Conscious shortening of the phase of deep immersion in dreams over several nights and the result is obvious: decreased concentration, deterioration of memory and performance.

Processes that occur during delta sleep

Each adult has his own norm for the deep sleep phase. For some, 5 hours a day is enough, but some don’t feel their best even after 9 hours in bed. It has been noticed that the deep phase shortens with age.

Not only is the slow-wave sleep phase divided into stages, but deep immersion into the kingdom of Morpheus is heterogeneous and consists of several stages:

1. At the initial stage, there is an awareness and storage of the difficulties encountered during the day. The brain searches for answers to emerging problems while awake.
2. Next comes a stage called “sleep spindles.” The muscles are relaxed as much as possible, and breathing and heartbeat are slowed down. At this stage, hearing may become more acute.
3. Then, for 15-20 minutes, the delta phase begins, differing in its depth.
4. Delta sleep of maximum strength. At this time, it is quite difficult to wake a person. Large-scale processes are underway in the brain to reconstruct performance.

If you wake up a person at the stage of deep sleep, he does not feel rested, but broken and tired. Waking up at the end of the fast phase is considered more physiological. At this time, the work of the senses is activated and light noise is enough to wake up.

The following processes occur in the body during sound and deep sleep:

• The rate of metabolic processes is significantly reduced, the body seems to save energy.
• The parasympathetic nervous system is activated, which leads to a decrease in heart rate and blood pressure. The speed of blood flow also decreases.
• The brain requires less oxygen.
• The activity of processes in the digestive system is reduced.
• Growth hormone is being produced.
• Restoration work is carried out in the cells.
• The adrenal glands reduce their hormone production activity.
• The immune system is at its peak. It’s not for nothing that they say that sleep is the best medicine.

The listed processes confirm the importance of the deep stage for the body, but the fast or paradoxical phase should also not be underestimated. It has been established through experiments that deprivation of REM sleep over several nights is fraught with the development of mental disorders.

Sensational discovery of delta sleep peptide

Long-term research in the field of dreams was crowned with success by scientists in the 70s. They were able to discover the delta sleep peptide. The donors of this substance were experimental rabbits, in whose blood it was discovered when the animals were immersed in deep sleep. If they influence the brain, it can cause the onset of deep sleep.

After such a discovery, scientists every year only find more evidence of the beneficial properties of the peptide. They are as follows:

• Defense mechanisms in the body are activated.
• Thanks to antioxidant properties, the aging process occurs at a slower rate; for example, in experimental mice, life expectancy increased by almost 25%.
• The peptide has the ability to slow down the growth of cancer tumors and suppress the formation of metastases.
• The development of dependence on alcoholic beverages is inhibited.
• Due to its anticonvulsant properties, the duration of seizures during epilepsy is reduced.
• Has an analgesic effect.

If only everyone had such a magical substance, take it in front of the bedroom door and fall into a healthy and rejuvenating sleep.

Normal duration of the deep phase of night rest

It is impossible to say with certainty how much deep sleep is normal for an adult. Everyone’s body is individual, for example, Napoleon got enough sleep and recovered in just 4 hours, but Einstein needed 10 for this. Each person has their own indicators, but one thing can be said: if a person consciously or forcedly reduces the necessary need for rest, he will immediately feel tired and brokenness.

As for the patterns in the norms, we found out through experiments. People of different age categories were invited to participate. It was possible to establish that it took young people just over 7 hours to recover, middle-aged people 6.5, and pensioners about 6. The same pattern was observed in the duration of the deep phase.

Research results may mean that the need for the delta phase depends on age, general health, weight, daily routine, and characteristics of psychological processes.

It is important that each person provides himself with the amount of night rest that his body requires to recover. Otherwise, the endocrine system suffers and brings with it a bunch of problems.

Reasons that disrupt delta sleep

Many people may suffer from sleep disturbances from time to time, but this does not entail negative consequences for the body. An important project that needs to be completed, preparing for exams require a reduction in rest time, but everything passes, and the body can compensate by sleeping longer than usual.

If there is a lack of proper and normal rest for a long time, then this is a reason to look for a reason to eliminate it. The most likely and most common factors include the following factors that deprive a person of the delta phase:

• Chronic stress.
• Psychical deviations.
• Pathologies of internal organs.
• Diseases of the musculoskeletal system.
• Heart diseases.
• Diabetes.
• Arterial hypertension.
• Males have diseases of the pelvic organs, for example, prostatitis, which causes frequent urination.
• Psycho-emotional overload.

Only by establishing the cause of disturbances in night rest can you understand what to do to eliminate it. If you cannot do this yourself, you will have to seek help from a specialist.

Quite often, the cause of violations is workaholism and the desire to do as much as possible to earn money. But the paradox of the situation is that with chronic lack of sleep, labor productivity drops, performance decreases, memory and concentration suffer. As a result, it is not possible to redo everything, and the body suffers.

This is especially true for people with mental work. But for all other categories of citizens, if night sleep lasts systematically less than it should for the body, then after some time the following consequences will certainly not be avoided:

• Diseases will begin to overcome because the immune system ceases to cope with its responsibilities.
• The concentration of attention decreases, what this will lead to if a person is driving is probably understandable.
• Oddly enough, we sleep less, but our weight increases.
• The appearance immediately reveals sleepless nights: bags under the eyes, gray and tired skin color, wrinkles.
• The risk of developing cancer increases.
• Heart problems appear.
• Memory fails, the brain simply does not have time to process information in a short period of time and sort it in order to retrieve it when necessary.

How to correct delta sleep

The duration of this phase is individual for everyone, but if there is a deficiency, serious consequences arise for the body. To avoid this, you must make every effort to increase the percentage of deep sleep during the night. You need to start with the simplest steps:

• Create an individual sleep and wake schedule for yourself and try to stick to it. The body gets used to going to bed at the same time, which improves the quality of rest.
• Fresh air and light physical activity will make your night's rest stronger.
• You just have to get rid of bad habits, for example, smoking, and the delta phase will increase.
• Ensure maximum silence in the room during night rest, remove light sources.

Experts in the field of studying sleep and its impact on human health give advice on increasing the duration of the delta stage of sleep:

1. Eliminate distracting sounds from the bedroom, such as a ticking clock. If you are afraid of oversleeping, it is better to set an alarm clock. But it has been established that sharp sounds are stressful for the awakening body: muscle tension appears, the heart begins to beat faster.
2. Exercising 2-4 hours before bedtime and a nice warm shower will speed up falling asleep.

An interesting fact has been established: if a few hours before bedtime the body temperature is increased by a couple of degrees, then after falling asleep it will drop, guaranteeing a biological decline that will strengthen night's rest.

1. Meditation accompanied by pleasant, relaxing music will help improve the quality of your sleep.
2. Avoid heavy dinners and coffee before bed. But it’s better not to go to bed hungry; a sharp drop in blood glucose levels will disrupt your rest.
3. Aromatic oils are suitable for better falling asleep and increasing sleep soundness, for example, apple aroma or vanilla are relaxing and soothing. You can add a couple of drops of sage, mint, and valerian oil to the aroma lamp.
4. Going to bed no later than 23 hours, and a new day should begin with sunrise, as our ancestors lived, according to the rhythms of nature and they had everything in order with sleep.
5. There is no need to disrupt your usual routine on weekends; it allows you to shift your awakening by a maximum of an hour so as not to disturb biological rhythms.

If there are serious problems with the quality of night's rest, then it is better to solve them with a doctor, but to get deep and sound sleep, in order to feel rested and full of strength in the morning, it is enough to follow simple recommendations.

Somnology is a fairly young science, and many aspects of it still baffle scientists, from surprising disorders like sexsomnia to the question of why we need to sleep with dreams in the first place. Somnologist Irina Zavalko told Theories and Practitioners about fragmented sleep and Kleine-Lewin syndrome, whether gadgets like Jawbone Up help you get enough sleep, whether it is possible to extend the deep sleep phase at all and whether it is useful to do this.

Time recently reported that nearly half of American teenagers don't get enough sleep. Is lack of sleep a disease of our time?

Indeed, attitudes towards sleep have changed in many ways - and at the end of the 19th century, people slept on average an hour more than we do now. This is associated with the “Edison effect”, and the root cause of this is the invention of the light bulb. Now there are even more entertainments that we can do at night instead of sleeping - computers, TVs, tablets, all this leads to the fact that we reduce our sleep time. In Western philosophy, sleep has long been viewed as a borderline state between being and non-being, which has grown into the belief that it is a useless waste of time. Aristotle also considered sleep as something borderline, unnecessary. People tend to sleep less, following another Western belief, especially popular in America, that those who sleep less spend their time more efficiently. People don’t understand how important sleep is for health and well-being, and normal performance during the day is simply impossible if you don’t get enough sleep at night. But in the East there has always been a different philosophy, it was generally accepted that sleep is an important process, and they devoted enough time to it.

Has the faster pace of life caused more sleep disorders?

It depends on what is considered a disorder. There is such a concept - inadequate sleep hygiene: insufficient sleep duration or incorrect, inappropriate conditions for sleep. Perhaps not everyone suffers from this, but a lot of people all over the planet do not get enough sleep - and the question is whether to consider this a disease, a new norm, a bad habit. On the other hand, insomnia is quite common today, which is also associated with the “Edison effect” that we talked about earlier. Many people spend time in front of the TV, computer or tablet before bed; the light from the screen shifts circadian rhythms, preventing a person from falling asleep. The frantic pace of life also leads to this - we return late from work and immediately try to fall asleep - without a pause, without a transition to a calmer state from such an excited state. The result is insomnia.

There are other disorders - apnea, sleep apnea, which appear along with snoring, which few people know about. The person himself, as a rule, is not aware of them if the breathing stops are not heard by relatives sleeping nearby. Our statistics are small in terms of the duration of the measurement, but this disease is probably also becoming more common - apnea is associated with the development of excess weight in adults, and given that the prevalence of overweight and obesity is growing, it can be assumed that apnea is too. The frequency of other diseases is increasing, but to a lesser extent - in children these are parasomnias, for example, sleepwalking. Life becomes more stressful, children sleep less, and this may be a predisposing factor. As life expectancy increases, many people live to develop neurodegenerative diseases, which can manifest as disordered behavior during the dream phase of sleep, when a person begins to manifest his dreams. This often occurs with Parkinson's disease or before symptoms begin. Periodic movement syndrome and “restless legs” syndrome, when a person feels discomfort in the legs in the evening, are also quite common. This may be pain, burning, itching, which forces you to move your legs and prevents you from falling asleep. At night, the movement of the legs continues, the person does not wake up, but sleep becomes restless and more superficial. If periodic movement of the legs during sleep interferes with a person, then it is considered a separate disease. If it does not disturb his sleep - the person gets enough sleep, feels comfortable, does not wake up often at night, falls asleep peacefully, wakes up refreshed in the morning, then this is not a disease.

I wanted to discuss with you the strangest sleep disorders - the Internet mentions sleeping beauty syndrome, and the twenty-four hours on your feet syndrome (non-24), when a person sleeps 24 hours a day, and fatal familial insomnia, and sexsomnia, and overeating during sleep . Which of these lists are real clinical disorders recognized by science?

The last three are real. Sleep eating and sexsomnia exist, but are quite rare - this is a disease of the same kind as sleepwalking, but manifests itself in specific activity during sleep. Fatal familial insomnia is also a fairly rare disease, it occurs mainly in Italians, and is hereditary. The disease is caused by a certain type of protein, and this is a terrible disease: a person stops sleeping, his brain begins to deteriorate, and gradually he goes into a state of oblivion - either he sleeps, or he doesn’t sleep and dies. Many insomnia patients fear that insomnia will somehow destroy their brain. Here the mechanism is the opposite: first the brain is destroyed, and because of this the person does not sleep.

Daily cycles of sleep and wakefulness are theoretically possible. When scientists conducted experiments in a cave where there were no time sensors - no sun, no clock, no daily routine, their biorhythms changed, and some switched to a forty-eight-hour sleep-wake cycle. The likelihood that a person will sleep for twenty-four hours without a break is not very high: it will be more likely to be twelve, fourteen, sometimes sixteen hours. But there is a disease when a person sleeps a lot - the so-called hypersomnia. It happens that a person sleeps a lot all his life, and this is normal for him. And there are pathologies - for example, Kleine-Lewin syndrome. It most often occurs in boys during adolescence, when they enter hibernation, which can last several days or a week. During this week, they only get up to eat, and are quite aggressive at the same time - if you try to wake them up, there is very pronounced aggression. This is also a rare syndrome.

What is the most unusual disease you have encountered in your practice?

I examined the boy after the first episode of Kleine-Lewin syndrome. But there is also a very interesting sleep-wake disorder that is not talked about much - narcolepsy. We know the absence of what substance causes it, there is a genetic predisposition to it, but it probably has autoimmune mechanisms - this is not fully understood. In patients with narcolepsy, the stability of being awake or asleep is impaired. This manifests itself as increased sleepiness during the day and unstable sleep at night, but the most interesting symptoms are the so-called cataplexy, when a mechanism is activated while awake that completely relaxes our muscles. A person experiences a complete drop in muscle tone - if in the whole body, then he falls down as if knocked down and cannot move for some time, although he is fully conscious and can retell everything that is happening. Or a drop in muscle tone may not completely affect the body - for example, only the muscles of the face or chin relax, or the arms fall. This mechanism normally works during sleep with dreams, but in these patients it can be triggered by emotions - both positive and negative. Such patients are very interesting - I had a patient who argued with his wife during an appointment. As soon as he got irritated, he fell into this unusual state, and his head and hands began to fall.

When do you think science has talked more about sleep - in the last century, when it received excessive attention in connection with psychoanalysis, or now, when these diseases are increasingly occurring?

Previously, there was a more philosophical approach to everything - and the study of sleep resembled philosophical reasoning. People began to think about what causes sleep. There were ideas about sleep poison - a substance that is released during wakefulness and puts a person to sleep. They searched for this substance for a long time, but never found it; Now there are some hypotheses regarding this substance, but it has not yet been found. At the end of the 19th century, our great compatriot Marya Mikhailovna Manaseina, conducting experiments on sleep deprivation on puppies, found out that lack of sleep is fatal. She was one of the first to declare that sleep is an active process.

Many people talked about sleep then, but few supported their reasoning with experiments. Now a more pragmatic approach is being taken to the study of sleep - we are studying specific pathologies, smaller sleep mechanisms, and its biochemistry. The encephalogram, which was invented by Hans Berger at the beginning of the last century, allowed scientists to understand from specific brain waves and additional parameters (we always use eye movement and muscle tone) whether a person is sleeping or awake - and how deeply. The encephalograph revealed that sleep is a heterogeneous process and consists of two fundamentally different states - slow and fast sleep, and this scientific knowledge gave the next impetus to development. At some point, doctors became interested in sleep, and this process was triggered by the understanding of apnea syndrome - as a factor leading to the development of arterial hypertension, as well as heart attacks, strokes and diabetes mellitus, and in general to a greater risk of death. From this moment on, a surge in clinical somnology in medicine began - the appearance of equipment and sleep laboratories among specialists, most represented in America, Germany, France, and Switzerland. A somnologist is not as rare there as it is here, he is an ordinary specialist. And the emergence of a large number of doctors and scientists led to new research - new diseases began to be described, the symptoms and consequences of previously known ones were clarified.

British journalist David Randall, author of The Science of Sleep, wrote that for a professional scientist to deal with sleep problems is like admitting that he is looking for the lost Atlantis. Do you agree with him?

The importance of sleep was initially underestimated. Doctors most often ask their patients about everything related to wakefulness. We somehow forget that normal wakefulness is impossible without proper sleep, and during wakefulness there are special mechanisms that keep us in a state of activity. Not all experts understand why it is necessary to study these mechanisms - the mechanisms of the transition between sleep and wakefulness, as well as what happens during sleep. But somnology is a very interesting field that still conceals many secrets. For example, we don’t know exactly why this process is needed, during which we completely disconnect from the outside world.

If you open a biology textbook, only one short chapter will be devoted to sleep. Of the doctors and scientists who deal with any specific function of the body, few try to track what happens to it in a dream. This is why sleep scientists seem a little isolated. There is no widespread dissemination of knowledge and interest - especially in our country. Biologists and doctors practically do not study the physiology of sleep during their training. Not all doctors know about sleep disorders; the patient may not receive a referral to the right specialist for a long time, especially since all our specialists are rare and our services are not covered by compulsory medical insurance (compulsory health insurance system). We do not have a unified system of sleep medicine in the country - there are no standards of treatment, no referral system to specialists.

Do you think that in the near future somnology will move from a special medical field to a general one, and it will be dealt with by a gastroenterologist, an allergist, and a phthisiatrician?

This process is already underway. For example, the European Respiratory Society included sleep apnea, its diagnosis and treatment in the list of necessary knowledge for any pulmonologist. Also, little by little this knowledge is spreading among cardiologists and endocrinologists. How good or bad this is is debatable. On the one hand, it is good when a doctor who has direct contact with the patient has a variety of knowledge and can suspect and diagnose the disease. If you do not ask a person with persistent arterial hypertension whether he snores in his sleep, you may simply miss the problem and the cause of this arterial hypertension. And such a patient simply will not go to a sleep specialist. On the other hand, there are cases that require deeper knowledge, a doctor who understands the physiology and psychology of sleep, changes occurring in the respiratory and cardiovascular systems. There are difficult cases when consultation with a sleep specialist is required. In the West, a system is gradually emerging where people are referred to a somnologist only if diagnostic procedures and selection of treatment carried out by broader specialists are not successful. But it happens the other way around, when a somnologist makes a diagnosis and refers a patient with apnea to a pulmonologist to select treatment. This is also an option for successful interaction. Somnology is multidisciplinary and requires an integrated approach, sometimes involving a number of specialists

How speculative do you think the New York Times article is that white Americans sleep more overall than people of color? Are genetic and cultural differences possible here?

No, this is not speculation. Indeed, there are interethnic and interracial differences in both sleep duration and the incidence of various diseases. The reasons for this are both biological and social. Sleep requirements vary from four to twelve hours per person, and this distribution varies among different ethnic groups, as do some other indicators. Differences in lifestyle also affect the duration of sleep - the white population tries to monitor their health to a greater extent and lead a healthy lifestyle. There may also be cultural differences - Western philosophy argues that you need to sleep less and that a successful person can control his sleep (decide when to go to bed and get up). But in order to fall asleep, you need to relax and not think about anything - and adhering to this philosophy, at the slightest problems with sleep, a person begins to worry that he has lost control over his sleep (which he never had), and this leads to insomnia. The idea that sleep can be easily manipulated - for example, by going to bed five hours earlier or later - is wrong. In more traditional societies there are no such ideas about sleep, so insomnia is much less common.

The desire to control one's life in our society seems to have become excessive. Do you recommend any sleep apps to your patients?

Devices for regulating sleep are in great demand and are widespread in the modern world. Some can be called more successful - for example, running and light alarm clocks that help a person wake up. There are other gadgets that supposedly detect when a person sleeps more superficially and when more deeply, that is, they supposedly determine the structure of sleep according to some parameters. But the manufacturers of these devices do not talk about how the measurements are made; this is a trade secret - therefore their effectiveness cannot be confirmed scientifically. Some of these gadgets supposedly know how to wake a person at the most appropriate time. The idea is good, there is scientific data on the basis of which such approaches can be developed, but how they are carried out by a specific gadget is not clear, so it is impossible to say anything definite about this.

Many patients begin to worry about the information that these gadgets provide. For example, one young, healthy person, according to the gadget, only half of his sleep during the night turned out to be deep, and the other half - shallow. Here we must again note that we do not know what this gadget calls shallow sleep. Also, it's normal to stay awake all night. Typically, twenty to twenty-five percent of our sleep duration is dreaming sleep. Deep slow-wave sleep lasts another twenty to twenty-five percent. In older people, its duration decreases and it may disappear completely. But the remaining fifty percent may occupy more superficial stages - they last quite a long time. If the user does not have an understanding of the processes behind these numbers, then he may decide that they do not correspond to the norm and begin to worry about it.

But what is the norm? It just means that most people sleep like this. This is how norms are built in medicine and biology. If you are different from them, it is not at all necessary that you are sick with something - maybe you just did not fall into this percentage. To develop standards, you need to conduct a lot of research with each gadget.

Can we somehow prolong the phases of deep sleep, which are generally believed to bring more benefits to the body?

In fact, we don’t know much - we have an idea that deep slow-wave sleep better restores the body, and that REM sleep is also necessary. But we don't know how important the superficial drowsiness of the first and second stages is. And perhaps what we call superficial sleep has its own very important functions - related, for example, to memory. In addition, sleep has a certain architecture - we constantly move from one stage to another throughout the night. Perhaps it is not so much the duration of these stages that is of particular importance, but the transitions themselves - how frequent they are, how long they last, and so on. Therefore, it is very difficult to talk about exactly how to change sleep.

On the other hand, there have always been attempts to make your sleep more effective - and the first sleeping pills appeared precisely as a tool for optimal regulation of your sleep: to fall asleep at the right moment and sleep without waking up. But all sleeping pills change the structure of sleep and lead to more shallow sleep. Even the most modern sleeping pills negatively affect the structure of sleep. Now they are actively trying - both abroad and in our country - a variety of physical influences that should deepen sleep. These could be tactile and audio signals of a certain frequency that should lead to more slow wave sleep. But we must not forget that we can influence our sleep much more simply by what we do while awake. Physical and mental activity during the daytime promotes deeper sleep and helps you fall asleep more easily. Conversely, when we are nervous and experience some exciting events immediately before sleep, it becomes harder to fall asleep, and sleep may become more superficial.

Somnologists have a negative attitude towards sleeping pills and try to avoid their long-term daily prescription. There are many reasons for this. First of all, sleeping pills do not restore the normal structure of sleep: the number of deep stages of sleep, on the contrary, decreases. After some time of taking sleeping pills, addiction develops, that is, the drug begins to act worse, but the developed dependence leads to the fact that when you try to stop sleeping pills, sleep becomes even worse than before. In addition, a number of drugs have a duration of elimination from the body of more than eight hours. As a result, they continue to act throughout the next day, causing drowsiness and a feeling of weakness. If a somnologist resorts to prescribing sleeping pills, he chooses drugs with faster elimination and less addiction. Unfortunately, other doctors, neurologists, therapists, and so on, often treat sleeping pills differently. They are prescribed at the slightest complaint of poor sleep, and they also use those drugs that take a very long time to be eliminated, for example, Phenazepam.

It is clear that this is the topic of an entire lecture, and perhaps more than one - but still: what happens in our body during sleep - and what happens if we do not get enough sleep?

Yes, this is not even the topic of a lecture, but a series of lectures. We know for sure that when we fall asleep, our brain disconnects from external stimuli and sounds. The coordinated work of the orchestra of neurons, when each of them turns on and falls silent at its own time, is gradually replaced by synchronization of their work, when all neurons either fall silent together or are all activated together. During REM sleep, different processes occur, it is more similar to wakefulness, there is no synchronization, but different parts of the brain are used differently, not in the same way as in wakefulness. But during sleep, changes occur in all systems of the body, not just in the brain. For example, growth hormones are released more in the first half of the night, and the stress hormone, cortisol, has a peak concentration in the morning. Changes in the concentration of some hormones depend specifically on the presence or absence of sleep, while others depend on circadian rhythms. We know that sleep is necessary for metabolic processes, and lack of sleep leads to obesity and the development of diabetes. There is even a hypothesis that during sleep the brain switches from processing information processes to processing information from our internal organs: intestines, lungs, heart. And there is experimental data confirming this hypothesis.

With sleep deprivation, if a person does not sleep at least one night, performance and attention decrease, mood and memory worsen. These changes disrupt a person's daily activities, especially if these activities are monotonous, but if you put yourself together, you can get the job done, although the possibility of error is greater. There are also changes in the concentration of hormones and metabolic processes. An important question that is much more difficult to study is what happens when a person gradually loses sleep every night? Based on the results of experiments on animals, we know that if a rat is not allowed to sleep for two weeks, then irreversible processes occur in it - not only in the brain, but also in the body: stomach ulcers appear, hair falls out, and so on. As a result, she dies. What happens when a person systematically lacks sleep, for example, two hours a day? We have indirect evidence that this leads to negative changes and various diseases.

What do you think about fragmented sleep - is it natural for humans (supposedly this is how people slept before electric light) or, on the contrary, harmful?

Man is the only living creature that sleeps once a day. It's more of a social aspect of our lives. Although we consider this to be the norm, it is not the norm for any other animal, and apparently not for the human species either. Siestas in hot countries testify to this. Initially, it is common for us to sleep in separate pieces - this is exactly how small children sleep. The formation of a single sleep occurs gradually in the child, at first he sleeps several times a day, then sleep gradually begins to shift to the night hours, the child has two periods of sleep during the day, then one. As a result, an adult sleeps only at night. Even if the habit of sleeping during the day continues, our social life interferes with this. How can a modern person sleep several times a day if he has an eight-hour working day? And if a person is used to sleeping at night, any attempts to get sleep during the day can lead to sleep disturbances and interfere with normal sleep at night. For example, if you come home from work at seven or eight o'clock and go to bed for an hour to take a nap, then falling asleep later at the usual time - at eleven o'clock - will be much more difficult.

There are attempts to sleep less by breaking up sleep - and this is a whole philosophy. I have a negative attitude towards this, like any attempts to change the structure of sleep. Firstly, it takes us a lot of time to fall into the deep stages of sleep. On the other hand, if a person is used to sleeping several times a day and this does not cause any problems for him, if he always falls asleep well when he wants, and does not feel tired and groggy after sleep, then this schedule is suitable for him. If a person does not have the habit of sleeping during the day, but he needs to cheer up (for example, in a situation where he needs to drive a car for a long time or an office worker during long monotonous work), then it is better to take a little nap, fall asleep for ten to fifteen minutes, but not plunge into deep sleep. dream. Shallow sleep is refreshing, and if you wake up from a state of deep sleep, “sleep inertia” may remain - fatigue, weakness, a feeling that you are less alert than you were before sleep. You need to figure out what suits a particular person best at a particular moment, you can try certain options - but I would not religiously believe and unconditionally follow one or another theory.

What do you think about lucid dreaming? It seems like everyone around them is into them now.

Dreams are very difficult to study scientifically, because we can only judge them from the stories of dreamers. To understand that a person had a dream, we need to wake him up. We know that lucid dreaming is something different as a process from normal dreaming sleep. Technologies have emerged that help us turn on consciousness during sleep and begin to be fully aware of our sleep. It is a scientific fact that people who lucid dream can give signals by moving their eyes to indicate that they have entered a lucid dreaming state. The question is how necessary and useful it is. I will not give arguments for it - I believe that this dream can be dangerous, especially for people with a predisposition to mental illness. In addition, it has been shown that if you practice lucid dreaming at night, deprivation syndromes arise, as if the person is not getting regular sleep with dreams. We need to take this into account, because we need sleep and dreams for life, why - we don’t fully know, but we know that it is involved in vital processes.

Can lucid dreaming cause sleep paralysis?

During the sleep phase with dreams, including lucid dreams, it is always accompanied by a drop in muscle tone and the inability to move. But upon awakening, muscle control is restored. Sleep paralysis is quite rare and can also be a symptom of narcolepsy. This is a state when, upon awakening, consciousness has already returned to a person, but control over the muscles has not yet been restored. This is a very frightening condition, scary if you cannot move, but it passes very quickly. Those who suffer from this are advised not to panic, but simply to relax - then this condition will pass faster. In any case, real paralysis from whatever we do with sleep is impossible. If a person wakes up and cannot move an arm or leg for a long time, most likely a stroke occurred during the night.

One Bavarian city is developing an entire program to improve the sleep of its inhabitants - with lighting regimes, special schedules for schoolchildren and working hours, and improved treatment conditions in hospitals. What do you think cities will look like in the future - will they cater to all these specific needs for a good night's sleep?

This would be a good scenario, one might say ideal. Another thing is that the same rhythm of work is not suitable for all people; everyone has their own optimal time to start the working day and the duration of work without breaks. It would be better if a person could choose what time to start working and what time to finish. Modern cities are fraught with many problems - from bright signs and street lighting to constant noise, all of which disrupt a night's sleep. Ideally, you should not use TV and computer late at night, but this is the responsibility of each individual person.

What are your favorite sleep-themed books and movies? Where are they talking about dreams that are fundamentally incorrect?

There is a wonderful book by Michel Jouvet “Castle of Dreams”. Its author discovered paradoxical sleep, sleep with dreams, more than 60 years ago. He worked in this field for a very long time, he is well over eighty, and now he is retired and writes fiction books. In this book, he attributed many of his discoveries and those of modern somnology, as well as interesting thoughts and hypotheses, to a fictional person who lives in the 18th century and tries to study sleep through various experiments. It turned out interesting, and it actually has real relevance to scientific data. I highly recommend reading it. Of the popular science books, I like the book by Alexander Borbelli - he is a Swiss scientist; our ideas about sleep regulation are now based on his theory. The book was written in the 1980s, quite ancient considering the speed at which modern sleep medicine is developing, but it explains the basics very well and at the same time in an interesting way.

Who wrote fundamentally wrong about sleep... In science fiction there is an idea that sooner or later a person will be able to get rid of sleep - with pills or influence, but I don’t remember a specific work where this was talked about.

Do somnologists themselves suffer from insomnia - and what habits do you have that allow you to maintain sleep hygiene?

Our wonderful psychologist who deals with sleep regulation and insomnia, Elena Rasskazova, says that somnologists rarely suffer from insomnia because they know what sleep is. In order not to suffer from insomnia, the main thing is not to worry about emerging syndromes. Ninety-five percent of people experience insomnia for one night at least once in their lives. It is difficult for us to fall asleep on the eve of an exam, a wedding, or some significant event, and this is normal. Especially if you suddenly have to rearrange your schedule - some people are very rigid in this regard. I was the luckiest person in my life: my parents adhered to a clear daily routine and taught me this as a child.

Ideally, the regime should be constant, without jumps on weekends - this is very harmful, this is one of the main problems of the modern lifestyle. If on the weekend you went to bed at two and got up at twelve, and on Monday you want to go to bed at ten and get up at seven, this is unrealistic. To fall asleep, you also need time - you need to give yourself a break, calm down, relax, don’t watch TV, don’t be in bright light at this moment. Avoid sleeping in the afternoon as this will most likely make it difficult to fall asleep at night. When you can’t sleep, the main thing is not to get nervous - I would advise in such a situation not to lie or toss around in bed, but to get up and do something calm: a minimum of light and quiet activity, reading a book or doing household chores. And sleep will come.

For good health, it is important for any person to have healthy and regular sleep. You need to sleep a certain number of hours every night in order to feel good and be productive the next day. But sleep is a complex set of biological rhythms, including at least 4-5 cycles. Each of these cycles is characterized by a short and a long sleep phase. Moreover, it is the last phase that is very important, because it is responsible for the restoration of the body. What is the norm of deep sleep and what is this concept, we will consider below.

What is deep or slow-wave sleep?

As soon as a person falls asleep, the slow phase begins, which includes deep delta sleep. After a while, a fast or paradoxical phase begins instead. It is characterized by the presence of sleep, but at the same time the person may have movements and sounds.

The ratio of deep and light sleep changes throughout the night and towards the end it is deep sleep that predominates more and more.

In addition, if a person suffers from some pathologies, his time of deep sleep may increase, since during this period the body recovers as much as possible. And in case of illness, recovery is needed much more, so this phase increases.

How does the quality of deep sleep affect intelligence?

Scientists have repeatedly conducted experiments, the purpose of which is to find out what the norm of deep sleep is and how this process affects the state of the body. It has been proven that during deep sleep the body is restored and mental abilities are increased. So, immediately before going to bed, volunteers were told some words that had no connection with each other. It was found that the longer the delta sleep phase lasted, the more words the subject could remember.

These studies allowed scientists to conclude that depriving a person of a deep sleep phase is tantamount to the complete absence of this physiological process. If you shorten deep sleep, you will begin to lose concentration, your performance will drop, and your memory will deteriorate.

What happens during deep sleep

It must be said that each person has his own norm of deep sleep per night. Some people can sleep 5 hours, and this is enough for them, while others don’t even need 9. The older a person is, the less need he has for sleep. Thus, the norm of deep sleep in children (and it accounts for up to 80% of the total sleep duration) should be 7-9 hours in total, and for adults this figure is slightly less - 5-7 hours.

In general, the deep sleep phase is divided into the following stages:

1. At the first stage, all events that occurred during the day are recorded in deep memory. The brain analyzes the difficulties it has encountered and looks for solutions.
2. The next stage is the so-called “sleepy spindles”. At this time, the heartbeat and breathing slow down, the muscles completely relax.
3. The third stage is the deep delta phase of sleep lasting 15-20 minutes.
4. Next comes the most pronounced delta sleep, during which it is difficult to wake a person. It is at this time that the body resumes its working capacity as much as possible.

If you wake up during the deep sleep stage, you will feel tired and exhausted, so it is important to wake up at the end of the fast phase. It is during this period that the senses are most active, so even minimal noise can wake a person.

So, during deep sleep, the human body performs the following actions:

• all metabolic processes proceed more slowly as the body tries to save energy;
• the brain consumes less oxygen;
• the activity of the parasympathetic system increases, which causes a decrease in blood pressure, heart rate and blood flow speed;
• the activity of the digestive system decreases;
• the adrenal glands synthesize basic hormones with less intensity;
• growth hormone is produced;
• all cells of the body are restored;
• The immune system is maximally activated.

How long should deep sleep last?

It is impossible to say exactly what the norm of deep sleep is for a person. For example, Napoleon stated that four hours of sleep a day was enough for him, and Einstein slept all 10. But still, a certain norm of deep sleep in adults, by which you can navigate, has been established. To do this, an experiment was conducted in which many patients of different ages participated. The results showed that at a young age you need to have 7 hours of deep sleep, on average - half an hour less, and in pensioners the duration of this phase is reduced to 6 hours.

Thus, the duration of the delta phase depends on age, daily routine, psychological characteristics, weight and general health. At the same time, it is very important that everyone gets exactly as much sleep as they need so that the body has time to recover. Otherwise, problems of a psychological nature will first begin, and then deviations in the functioning of the endocrine system will appear.

Causes of delta sleep disturbance

Everyone can occasionally experience sleep disturbances, but such rare manifestations do not cause serious changes in the body. So, if you need to go without sleep for one night to complete a project or coursework, prepare for an exam and other purposes, the body will be able to compensate for the loss of rest. To do this, you can spend more time sleeping and getting enough sleep the next day.

But if proper rest is lost or shortened for a long time, you need to look for the cause of this phenomenon. Most often, a delta phase problem is observed in the following situations:

• psychical deviations;
• internal diseases;
• chronic stress;
• diseases of the musculoskeletal system;
• diabetes;
• high blood pressure;
• heart disease;
• prostatitis and other male diseases.

To get rid of deep or delta sleep disorders, it is necessary to find out the cause of this phenomenon. Most often you can do this yourself, but sometimes it is recommended to seek help from a somnologist.

For example, sleep is often disturbed among workaholics who have a very busy workday. They try to do as much as possible in a day to increase their earnings. But at the same time, such people do not take into account that chronic lack of sleep leads to decreased ability to work, loss of concentration and the ability to remember. Therefore, all the work still cannot be done, and the body suffers greatly from overwork and lack of sleep.

This habit is especially common among people who engage in mental work. Due to the absence of severe physical fatigue during work, they try to do as much as possible in a day. As a result, constant chronic fatigue leads to the following consequences:

• Infectious diseases appear periodically as the body becomes depleted and the immune capacity cannot cope with the increased load.
• The person becomes less attentive. He makes mistakes more often. In this condition it is especially dangerous to drive a car.
• With lack of sleep, body weight increases.
• Cardiac pathologies appear, and the risk of developing cancer increases.
• Appearance deteriorates significantly. Bags appear under the eyes, skin color becomes unhealthy, and wrinkles may form.
• Due to the fact that the brain does not rest normally, it ceases to cope with the entire load. Memory problems begin, difficulties arise with processing large amounts of information.

Methods for correcting deep sleep

Despite the fact that each person has his own individual duration of the deep sleep phase, its lack causes serious consequences for the body. Therefore, it is important to make every effort to maximize the percentage of delta sleep at night. To do this you can do the following:

• Create a sleep schedule that indicates what time you should go to bed and wake up. If you constantly adhere to it, the body will get used to it, and your sleep will be of better quality.
• Shortly before bedtime, it is recommended to be in the fresh air and perform light exercise.
• You need to give up bad habits, especially smoking.
• Prepare the room for sleeping - remove light sources, ensure complete silence.

Those who professionally study sleep and its deviations also give their advice on how to make delta sleep last longer.

Sleep is one of the most amazing states, during which organs - and especially the brain - work in a special mode.

From a physiological point of view, sleep is one of the manifestations of the body’s self-regulation, subordinate to the rhythms of life, a deep disconnection of a person’s consciousness from the external environment, necessary to restore the activity of nerve cells.

Thanks to adequate sleep, memory is strengthened, concentration is maintained, cells are renewed, toxins and fat cells are removed, stress levels are reduced, the psyche is unloaded, melatonin is produced - the sleep hormone, a regulator of circadian rhythms, an antioxidant and an immune protector.

Sleep duration according to age

Sleep serves as protection against hypertension, obesity, cancer cell division, and even damage to tooth enamel. If a person does not sleep for more than 2 days, his metabolism will not only slow down, but hallucinations may also begin. Lack of sleep for 8-10 days drives a person crazy.

At different ages, people need different amounts of sleep:

Unborn children sleep the most in the womb: up to 17 hours a day.

• Newborn babies sleep about the same amount: 14-16 hours.
• Babies between 3 and 11 months of age require 12 to 15 hours of sleep.
• At the age of 1-2 years – 11-14 hours.
• Preschoolers (3-5 years old) sleep 10-13 hours.
• Primary schoolchildren (6-13 years old) – 9-11 hours.
• Teenagers need 8-10 hours of rest at night.
• Adults (from 18 to 65 years old) – 7-9 hours.
• Elderly people over 65 years old – 7-8 hours.

Old people often suffer from insomnia due to ailments and physical inactivity during the day, so they sleep 5-7 hours, which in turn does not have the best impact on their health.

The value of sleep by hour

The value of sleep also depends on the time you go to bed: you can get enough sleep in an hour like a night or not get enough sleep at all. The table shows the phases of a person’s sleep by time of sleep efficiency:

Our ancestors went to bed and got up according to the sun. Modern people go to bed no earlier than one in the morning, the result is chronic fatigue, hypertension, oncology, and neuroses.

With the actual value of sleep at least 8 hours, the body regained strength for the next day.

Some southern cultures have a tradition of napping (siesta), and the incidence of stroke and heart attack is noted to be significantly lower there.

Features of awakening in each phase of sleep

Sleep is heterogeneous in its structure; it consists of several phases that have their own psychophysiological characteristics. Each phase is distinguished by specific manifestations of brain activity aimed at restoring different parts of the brain and organs of the body.

When it is better for a person to wake up according to the phases of sleep, how easy the awakening will be depends on the phase in which his sleep was interrupted.

During deep delta sleep, awakening is the most difficult due to incomplete neurochemical processes that occur during this stage. And here It is quite easy to wake up during REM sleep, despite the fact that during this period the most vivid, memorable and emotional dreams occur.

However, a chronic lack of REM sleep can be detrimental to your mental health. It is this phase that is necessary to restore neural connections between consciousness and subconscious.

Phases of sleep in humans

The peculiarities of the functioning of the brain and the changes in its electromagnetic waves were studied after the invention of the electroencephalograph. An encephalogram clearly shows how changes in brain rhythms reflect the behavior and state of a sleeping person.

The main stages of sleep - slow and fast. They are uneven in duration. During sleep, the phases alternate, forming 4-5 wave-like cycles from 1.5 to less than 2 hours.

Each cycle consists of 4 phases of slow-wave sleep, associated with a gradual decrease in a person’s activity and immersion in sleep, and one of rapid sleep.

NREM sleep predominates in the initial sleep cycles and gradually decreases, while the duration of REM sleep increases in each cycle. The threshold for a person’s awakening changes from cycle to cycle.

The duration of the cycle from the beginning of slow-wave sleep to the end of fast sleep in healthy people is about 100 minutes.

• Stage 1 is about 10% of sleep,
• 2nd – about 50%,
• 3rd 20-25% and REM sleep - the remaining 15-20%.

Slow (deep) sleep

It is difficult to answer unambiguously how long deep sleep should last, because its duration depends on what sleep cycle a person is in, so in cycles 1-3, the duration of the deep sleep phase can be more than an hour, and with each subsequent cycle the duration of deep sleep is greatly reduced.

The phase of slow, or orthodox, sleep is divided into 4 stages: drowsiness, sleep spindles, delta sleep, deep delta sleep.

Signs of slow-wave sleep are loud and rare breathing, less deep than during wakefulness, a general decrease in temperature, a decrease in muscle activity, smooth eye movements that freeze towards the end of the phase.

In this case, dreams are unemotional or absent; long and slow waves occupy an increasing place on the encephalogram.

It was previously believed that the brain rests at this time, but studies of its activity during sleep have refuted this theory.

Stages of slow-wave sleep

In the formation of slow-wave sleep, the leading role is played by such areas of the brain as the hypothalamus, raphe nuclei, nonspecific nuclei of the thalamus and the Moruzzi inhibitory center.

The main characteristic of slow-wave sleep (aka deep sleep) is anabolism: creation of new cells and cellular structures, tissue restoration; it occurs at rest, under the influence of anabolic hormones (steroids, growth hormone, insulin), proteins and amino acids. Anabolism leads to the accumulation of energy in the body as opposed to catabolism, which consumes it.

The anabolic processes of slow sleep begin at stage 2, when the body completely relaxes and recovery processes become possible.

It has been noticed, by the way, that active physical work during the day prolongs the deep sleep phase.

The onset of falling asleep is regulated by circadian rhythms, and they, in turn, depend on natural light. The approach of darkness serves as a biological signal to reduce daytime activity, and the time for rest begins.

Falling asleep itself is preceded by drowsiness: a decrease in motor activity and level of consciousness, dry mucous membranes, sticking eyelids, yawning, absent-mindedness, decreased sensitivity of the senses, slow heart rate, an irresistible desire to lie down, momentary lapses into sleep. This is how the active production of melatonin manifests itself in the pineal gland.

At this stage, the rhythms of the brain change insignificantly and you can return to wakefulness in a matter of seconds. Subsequent stages of deep sleep demonstrate an increasing loss of consciousness.

1. Napping, or Non-REM(REM - from English rapid eye movement) - the 1st stage of falling asleep with half-asleep dreams and dream-like visions. Slow eye movements begin, body temperature decreases, heart rate slows down, and on the brain encephalogram, alpha rhythms that accompany wakefulness are replaced by theta rhythms (4-7 Hz), which indicate mental relaxation. In this state, a person often comes to a solution to a problem that he could not find during the day. A person can be brought out of slumber quite easily.
2. Sleepy spindles– of medium depth, when consciousness begins to switch off, but the reaction to calling one’s name or crying of one’s child remains. The sleeper's body temperature and pulse rate decrease, muscle activity decreases; against the background of theta rhythms, the encephalogram reflects the appearance of sigma rhythms (these are altered alpha rhythms with a frequency of 12-18 Hz). Graphically, they resemble spindles; with each phase they appear less frequently, become wider in amplitude, and fade away.
3. Delta– without dreams, in which the brain encephalogram shows deep and slow delta waves with a frequency of 1-3 Hz and a gradually decreasing number of spindles. The pulse quickens slightly, the breathing rate increases with a shallow depth, blood pressure decreases, and eye movements slow down even more. There is a blood flow to the muscles and active production of growth hormone, which indicates the restoration of energy costs.
4. Deep delta sleep- complete immersion of a person into sleep. The phase is characterized by a complete shutdown of consciousness and a slowdown in the rhythm of delta wave oscillations on the encephalogram (less than 1 Hz). There is even no sensitivity to smells. The sleeping person's breathing is rare, irregular and shallow, and there is almost no movement of the eyeballs. This is a phase during which it is very difficult to wake a person. At the same time, he wakes up broken, poorly oriented in the environment and does not remember dreams. It is extremely rare in this phase that a person experiences nightmares, but they do not leave an emotional trace. The last two phases are often combined into one, and together they take 30-40 minutes. The usefulness of this stage of sleep affects the ability to remember information.

Stages of REM sleep

From the 4th stage of sleep, the sleeper briefly returns to the 2nd stage, and then the state of rapid eye movement sleep (REM sleep, or REM sleep) begins. In each subsequent cycle, the duration of REM sleep increases from 15 minutes to an hour, while sleep becomes less and less deep and the person approaches the threshold of awakening.

This phase is also called paradoxical, and here's why. The encephalogram again registers fast alpha waves with low amplitude, as during wakefulness, but at the same time the neurons of the spinal cord are completely switched off to prevent any movement: the human body becomes as relaxed as possible, muscle tone drops to zero, this is especially noticeable in the mouth and neck area .

Motor activity manifests itself only in the appearance of rapid eye movements(REM), during the period of REM sleep in a person, the movement of the pupils under the eyelids is clearly noticeable, in addition, body temperature rises, the activity of the cardiovascular system and the adrenal cortex increases. Brain temperature also rises and may even slightly exceed its waking level. Breathing becomes either fast or slow, depending on the plot of the dream that the sleeper sees.

Dreams are usually vivid, with meaning and elements of fantasy. If a person is awakened in this phase of sleep, he will be able to remember and tell in detail what he dreamed.

People who are blind from birth do not have REM sleep, and their dreams consist not of visual, but of auditory and tactile sensations.

In this phase, the information received during the day is adjusted between the conscious and subconscious, and the process of distributing the energy accumulated in the slow, anabolic phase takes place.

Experiments on mice confirm that REM sleep is much more important than non-REM sleep. That is why awakening in this phase artificially is unfavorable.

Sequence of sleep stages

The sequence of sleep stages is the same in healthy adults. However, age and various sleep disorders can fundamentally change the picture.

Newborn sleep, for example, consists of more than 50% REM sleep., only by the age of 5 the duration and sequence of stages becomes the same as in adults, and remains in this form until old age.

In older years, the duration of the rapid phase decreases to 17-18%, and the phases of delta sleep may disappear: this is how age-related insomnia manifests itself.

There are people who, as a result of a head or spinal cord injury, cannot sleep fully (their sleep is similar to light and brief oblivion or half-asleep without dreams) or go without sleep at all.

Some people experience numerous and prolonged awakenings, due to which a person is completely sure that he did not sleep a wink during the night. Moreover, each of them can wake up not only during the REM sleep phase.

Narcolepsy and apnia are diseases that demonstrate atypical progression of sleep stages.

In the case of narcolepsy, the patient suddenly enters the REM phase and can fall asleep anywhere and at any time, which can be fatal for him and those around him.

Apnia is characterized by sudden cessation of breathing during sleep. Among the reasons are a delay in the respiratory impulse coming from the brain to the diaphragm, or excessive relaxation of the muscles of the larynx. A decrease in the level of oxygen in the blood provokes a sharp release of hormones into the blood, and this forces the sleeper to wake up.

There can be up to 100 such attacks per night, and they are not always recognized by the person, but in general the patient does not receive proper rest due to the absence or insufficiency of certain phases of sleep.

If you have apnea, it is very dangerous to use sleeping pills; they can cause death from sleep apnea.

Also, the duration and sequence of sleep stages can be influenced by emotional predisposition. People with “thin skin” and those who are temporarily experiencing difficulties in life have an extended REM phase. And in manic states, the REM stage is reduced to 15-20 minutes throughout the night.

Rules for healthy sleep

Adequate sleep means health, strong nerves, good immunity and an optimistic outlook on life. You should not think that time passes in a dream uselessly. Lack of sleep can not only have a detrimental effect on your health, but also cause tragedy..

There are several rules for healthy sleep that ensure sound sleep at night and, as a result, excellent health and high performance during the day:

1. Stick to a bedtime and wake-up schedule. It is best to go to bed no later than 11 pm, and all sleep should take at least 8, ideally 9 hours.
2. Sleep must necessarily cover the period from midnight to five in the morning; during these hours the maximum amount of melatonin, the longevity hormone, is produced.
3. You should not eat food 2 hours before bedtime, as a last resort, drink a glass of warm milk. It is best to avoid alcohol and caffeine in the evening.
4. An evening walk will help you fall asleep faster.
5. If you have difficulty falling asleep, it is advisable to take a warm bath before bed with an infusion of soothing herbs (motherwort, oregano, chamomile, lemon balm) and sea salt.
6. Be sure to ventilate the room before going to bed. You can sleep with the window slightly open and the door closed, or open the window in the next room (or in the kitchen) and the door. To avoid catching a cold, it is better to sleep in socks. The temperature in the bedroom should not fall below +18 C.
7. It is healthier to sleep on a flat and hard surface, and use a bolster instead of a pillow.
8. Stomach position is the worst position for sleeping, the position on your back is most beneficial.
9. After waking up, a little physical activity is advisable: exercise or jogging, and, if possible, swimming.

Every day the human body requires night rest. Human sleep has its own characteristics and is divided into slow-wave sleep and fast-moving sleep. What is best for the human body was determined by scientists who proved that both cycles are necessary for proper rest.

Human sleep: its physiology

Daily sleep onset is a necessity. If a person is deprived of rest for three days, he becomes emotionally unstable, attention decreases, memory loss, and mental retardation occur. Psycho-neurotic overexcitation and depression predominate.

During sleep, all organs, along with the human brain, rest. At this time, people’s subconscious is switched off, and performance procedures, on the contrary, are launched.

To answer the question - slow sleep and fast sleep: which is better, you should first understand what is meant by these concepts

In modern science, the concept of sleep is interpreted as a periodic, functional period with specific behavior in the motor and autonomic spheres. At this time, immobility and disconnection from the sensory influence of the surrounding world occurs.

In this case, two phases alternate in a dream, with characteristic opposite characteristics. These stages are called slow and fast sleep.

The slow and fast cycle together restore mental and physical strength, activate the brain’s performance for information processing of the past day. In this case, the processed information is transferred from short-term memory to long-term memory.

This activity allows you to resolve problems accumulated during the day, as well as absorb the information that was received in the evening.

In addition, proper rest helps to improve the health of the body. When a person sleeps, he loses moisture, which is explained by slight weight loss. Collagen is produced in large quantities, which is necessary to strengthen blood vessels and restore the elasticity of the skin.

That's why, To look good you need at least 8 hours of sleep. While a person sleeps, his body cleanses itself in preparation for the next day.

There is no clear answer to the question of whether slow or fast sleep is better - only ¾ of sleep time is spent on slow sleep, but this is enough for proper rest.

Slow sleep cycle, its features

Features of slow-wave sleep are:

• increase and decrease in pressure;
• preservation of average pulse rhythm;
• decreased motor functions of the visual organs;
• muscle relaxation.

During the slow phase, the body relaxes, breathing slows down, and the brain loses sensitivity to external stimuli, which is an indicator of a difficult awakening.

In this phase, cell restoration occurs due to the production of a hormone responsible for tissue growth and renewal of the muscular body. During the slow phase, the immune system is also restored, which indicates the importance of slow sleep for the physiological state.

The main components of slow-wave sleep

NREM sleep is divided into 4 phases with diverse bioelectrical characteristics. When a person falls into slow-wave sleep, the body's activity decreases, and at this time it is difficult to wake him up. In the deep stage of slow-wave sleep, heart rate and breathing increase, and blood pressure decreases.

Slow sleep rehabilitates and heals the body, restores cells and tissue, which improves the condition of internal organs; fast sleep does not have such features.

Nap

When a person falls into a state of drowsiness, there is conjecture and revision of those ideas that appeared during daytime wakefulness. The brain is looking for solutions and possible correct ways out of current situations. Often people have dreams in which problems are solved with positive results.

Sleepy spindles

After dozing, the sleep spindle rhythm begins. The disabled subconscious alternates with a threshold of significant hearing sensitivity.

Delta sleep

Delta sleep has all the characteristic features of the previous stage, to which is added the delta oscillation of 2 Hz. The amplitude increase in the rhythm of oscillations becomes slower, and the transition to the fourth phase occurs.

Delta sleep is called the transitional stage to the deepest rest.

Deep delta sleep

This stage during slow-wave sleep is characterized by dreams, dull energy, and heavy lifting. A sleeping person is practically impossible to awaken.

The deep phase of delta sleep occurs 1.5 hours after going to bed. This is the final stage of slow-wave sleep.

Rapid sleep cycle, its features

REM sleep at night is called paradoxical or fast-wave sleep. At this time, changes occur in the human body. REM sleep has its own distinctive features:

• clear memory of a visible dream, which cannot be said about the slow-wave sleep phase;
• improved respiratory rate and arrhythmia of the cardiovascular system;
• loss of muscle tone;
• the muscle tissue of the neck and oral diaphragm stops moving;
• pronounced motor character of the apples of the visual organs under closed eyelids.

REM sleep with the onset of a new cycle has a longer duration, but at the same time, less depth, despite the fact that wakefulness approaches with each cycle, it is difficult to wake a person during REM sleep.

REM sleep has only two cycles: emotional; unemotional.

During the period of accelerated sleep, messages received the day before before rest are processed, data is exchanged between the subconscious and the mind. A quick night's rest is necessary for the person and the brain to adapt to changes in the surrounding space. Interruption of the sleep phase in question threatens mental disorders.

People who do not have proper rest are deprived of the opportunity to revive the protective functions of the psyche, as a result: lethargy, tearfulness, irritability, absent-mindedness.

Sequence of sleep stages

NREM sleep and REM sleep - which is better - cannot be answered unequivocally, since both phases perform different functions. The slow cycle begins immediately, followed by deep rest. During REM sleep, it is difficult for a person to wake up. This occurs due to disabled sensory perceptions.

Night rest has a beginning - it is a slow phase. First, the person begins to doze, this lasts a little less than a quarter of an hour. Then stages 2, 3, 4 begin gradually, this takes about another 60 minutes.

With each stage, sleep deepens, and a fast phase begins, which is very short. After it there is a return to phase 2 of slow-wave sleep.

The change between fast and slow rest occurs up to 6 times throughout the night.

After completing the stages under consideration, the person awakens. Waking up occurs individually for everyone; the awakening process takes from 30 seconds to 3 minutes. During this time, clarity of consciousness is restored.

Scientific research has shown that a person who is frequently deprived of REM sleep can end up dying.

The reason why self-destruct occurs is unknown. Other studies show that in some cases, when there is a lack of the fast phase, treatment of depressive conditions is noted.

What is the difference between slow and fast sleep?

The body behaves differently during one or another phase of sleep; the main differences between the cycles are shown in the table.

Slow sleep and REM sleep, which cannot be better defined, because there is a chemical, physiological, functional dependence between them, in addition, they participate in a single balanced process of rest of the body.

During a slow night's rest, internal rhythms in the brain structure are regulated; a quick rest helps to establish harmony in these structures.

When is it better to wake up: in the NREM or REM stage of sleep?

The general state of health and well-being of a person depends on the phase of waking up. The worst time to wake up is during deep sleep. Having awakened at this moment, a person feels weak and tired.

The best time to wake up is the first or second stage after REM sleep ends. Doctors do not recommend getting up during REM sleep.

Be that as it may, when a person has had enough sleep, he is cheerful and full of energy. Usually this happens immediately after a dream; it reacts to sound, lighting, and temperature conditions. If he gets up immediately, then his condition will be excellent, and if he still sits up, a new cycle of slow sleep will begin.

Waking up during slow-wave sleep, which usually occurs when the alarm clock rings, a person will be irritated, lethargic, and sleep-deprived.

That's why The best moment of awakening is considered to be the one when a person did it on his own, no matter what time is on the clock, the body is rested and ready to work.

It is impossible to judge which sleep is better; slow sleep is needed to restart, reboot and rest the body. REM sleep is needed to restore protective functions. Therefore, it is better to have a full sleep, without lack of sleep.

Video in sleep phases, slow and fast sleep

What is sleep, as well as what is meant by the concepts of “slow sleep” and “rapid sleep”, which is better - you will learn about all this from the video below:

Check out these tips on how to get good, healthy sleep: