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The processes that occur with a person during sleep

Процессы, которые происходят с человеком во время сна

Sleep (lat. Somnus) is a natural physiological process of staying in a state with a minimum level of brain activity and a reduced reaction to the surrounding world inherent in mammals, birds, fish, and some other animals, including insects (for example, fruit flies). In addition, the word "dream" refers to a sequence of images (formed during the phase of the so-called "fast sleep") that a person can remember (see also a dream). Physiologically, ordinary sleep is different from other conditions similar to it - anabiosis (so-called "hibernation" in animals), hypnotic sleep, coma, fainting, lethargic sleep.

1. Body temperature drops

Процессы, которые происходят с человеком во время сна

Since most muscles become inactive during sleep, the body burns fewer calories than during the day, and the body temperature drops. Scientists have found that body temperature is usually the lowest around 2:30 in the morning.

2. Eyes are moving

Процессы, которые происходят с человеком во время сна

Although the eyes in the dream are closed for centuries, they move under them. In fact, such a movement even differs depending on the specific stages of sleep.

3. The body twitches

Процессы, которые происходят с человеком во время сна

Sharp twitches and jerks are mainly associated with the first stage of sleep. They are usually harmless, but they can be strong enough to actually wake a person.

4. Muscles are relaxed.

Процессы, которые происходят с человеком во время сна

There is a good reason why most of the muscles during sleep are relaxed. If they were active, then a person could move around during sleep, which would be extremely dangerous.

5. The skin is restored

Процессы, которые происходят с человеком во время сна

The top layer of skin consists of tightly packed dead cells that are constantly shed throughout the day. During sleep, the metabolic rate of the skin is accelerated and in many cells of the body begins to increase activity and decrease protein breakdown. Since proteins are needed to grow and repair damage from such factors as ultraviolet radiation, deep sleep has a beneficial effect on the skin.

6. The brain forgets useless information.

Процессы, которые происходят с человеком во время сна

People perceive an insane amount of information throughout the day. If they remembered it all, they would soon go crazy. That is why at night the brain sorts information and forgets about unnecessary.

7. Throat narrows

Процессы, которые происходят с человеком во время сна

Unlike most other muscles, throat muscles do not paralyze during sleep, as they are necessary to breathe. However, they relax during sleep, causing the throat to narrow. It can also cause snoring.

8. The body produces hormones.

Процессы, которые происходят с человеком во время сна

During the slow sleep phase, the human body produces hormones that stimulate growth, cell reproduction and cell regeneration. It is an important regulator of the immune system.

9. The immune system is at an all-time high.

Процессы, которые происходят с человеком во время сна

It has been proven that sleep deprivation negatively affects the immune system. One study found that people who received flu shots and were deprived of sleep do not produce the antibodies necessary to protect against the flu the following night. Therefore, if a person noticed the first signs of infection, he should sleep.

10. Weight Loss

Процессы, которые происходят с человеком во время сна

During sleep, a person loses water by sweating and exhaling humid air. This also happens throughout the day, but food and drink nullify any weight loss. Therefore, for any diet you need a good and long sleep.

11. Dry mouth

Процессы, которые происходят с человеком во время сна

Since saliva is mainly needed for food, and the person does not eat while sleeping, the amount of saliva secreted decreases at night. Consequently, the mouth dries out, and in the morning often thirsty.

12. Teeth grinding

Процессы, которые происходят с человеком во время сна

Research estimates that about 5% of people suffer from a bizarre condition known as bruxism. This results in excessive gnashing of teeth during sleep and may eventually lead to damage to the teeth. Scientists are not sure what exactly causes this condition, but they believe that this may be a peculiar form of stress relief.

13. The body becomes longer

Процессы, которые происходят с человеком во время сна

It was found that the height of people can increase by a few centimeters in the morning, compared with the evening. During sleep in a horizontal position, the spine expands, because the body weight does not press on it.

14. Blood pressure drops sharply.

Процессы, которые происходят с человеком во время сна

During sleep, any person experiences a condition that is known as a "night decrease in blood pressure." On average, it falls by 5–7 mm at night. Hg Art.

15. Sleepwalking

Процессы, которые происходят с человеком во время сна

Scientifically known disorders, parasomnias (sleepwalking and other activities during sleep), include behaviors, emotions, sensations, and dreams that usually occur during transitions between some of the sleep stages. Parasomnias are mostly harmless, but there have been cases when people were injured during sleepwalking.

16. Sexual arousal

Процессы, которые происходят с человеком во время сна

Both men and women may become agitated during sleep. When the brain is more active during sleep, it requires more oxygen. As a result, blood flow throughout the body increases, which leads to swelling of the genitals.

17. Dreams

Процессы, которые происходят с человеком во время сна

The content and purpose of dreams are not fully understood, but it is known that an ordinary person has from 3 to 5 dreams per night. Dreams mainly occur in the first stage of sleep, when the human brain is the most active. However, most dreams are immediately or quickly forgotten.

18. The brain makes decisions

Процессы, которые происходят с человеком во время сна

A recent study showed that the brain can process information and prepare for further action during sleep, effectively making decisions in an unconscious state. In fact, the brain can even make important discoveries during sleep.

19. Flatulence

Процессы, которые происходят с человеком во время сна

The muscles of the anal sphincter weaken slightly during sleep, which facilitates the exit of gases from the intestine. The good news is that the sense of smell also weakens during sleep.

20. Purification of toxins

Процессы, которые происходят с человеком во время сна

Getting rid of toxins allows the body and brain to recuperate. For people who do not sleep well, filtering harmful substances is not so effective, so experts say: this is what causes insomniac people to be a little crazy.

21. Unconscious Awakening

Процессы, которые происходят с человеком во время сна

Scientific studies have shown that people wake up many times during sleep, but these awakenings are so short that they do not remember them. As a rule, these wakes occur during the transitional periods between sleep stages.

22. You can stop breathing

Процессы, которые происходят с человеком во время сна

Millions of people all over the world suffer from a sleep disorder known as apnea. The disorder is characterized by pauses between breaths when breathing, and each pause can last for a few seconds or even a few minutes.

23. Can hear an explosion

Процессы, которые происходят с человеком во время сна

“Exploding Head Syndrome” is a rare condition in which a person hears loud imaginary sounds (such as a bomb explosion, a shooting sound, etc.) or has a strange feeling of an explosion when falling asleep or waking up. It is painless, but scares the sufferer.

24. Conversations during sleep

Процессы, которые происходят с человеком во время сна

Conversations during sleep are parasomnias, in which a person begins to uncontrollably chatter out loud during sleep. Such "conversations" can be quite loud and can be either simple, gibbering sounds, or long, often slurred speeches.

Sleep physiology

Процессы, которые происходят с человеком во время сна

In a dream the level of anabolic processes increases and the catabolism decreases. Sleep normally occurs cyclically, approximately every 24 hours. These cycles are called circadian rhythms. They are redefined every day, the most important factor is the level of lighting. The concentration of specific photo-dependent proteins depends on the natural light cycle. The circadian cycle is usually tuned to the length of daylight. In addition to a night's sleep, in some cultures there is a physiologically related short-term daytime sleep - siesta.

Falling asleep

Immediately before bedtime comes a state of drowsiness, a decrease in brain activity, characterized by:

  1. a decrease in the level of consciousness;
  2. yawn;
  3. decrease the sensitivity of sensory systems;
  4. a decrease in heart rate, a decrease in the secretory activity of the glands (salivary - dry mouth mucosa; tears - burning eyes, sticking of the eyelids).

Professor Richard R. Budzin has been studying sleep disorders for many years at the University of Arizona's Sleep Research Lab and recommends rapid sleep techniques based on six steps. In the annual report on clinical psychology, he described various psychological approaches that were used to treat insomnia (Bootzin & Epstein, 2011). Such treatment was even earlier called treatment stimulus control (Morin et al., 2006). Tips include: go to bed, only when you want to sleep, use the bed only for sleep, do not lie in bed for more than 10 minutes, if you cannot fall asleep - make the bed only associated with a fast sleep, wake up in the morning with an alarm clock in one same time, do not sleep during the day.

Sleep structure

Sleep is a special state of consciousness of humans and animals, including a series of stages, regularly repeated during the night (with a normal daily schedule). The appearance of these stages is due to the activity of various brain structures.

In a healthy person, sleep begins with the first stage of slow sleep (Non-REM sleep), which lasts 5-10 minutes. Then comes the 2nd stage, which lasts about 20 minutes. Another 30-45 minutes falls on a period of 3-4 stages. After that, the sleeper again returns to the 2nd stage of slow sleep, after which the first episode of REM sleep occurs, which has a short duration of about 5 minutes. This whole sequence is called a loop. The first cycle has a duration of 90-100 minutes. Then the cycles are repeated, while the share of slow sleep decreases, and the share of fast sleep (REM-sleep) gradually increases, the last episode of which in some cases can reach 1 hour. On average, with full healthy sleep, there are five full cycles. The sequence of stages and their duration is conveniently represented in the form of a hypnogram, which clearly reflects the structure of the patient's sleep.

Slow sleep

Slow sleep (syn .: slow wave sleep, orthodox sleep) lasts 80-90 minutes. It comes immediately after falling asleep.

  • The first stage. The alpha rhythm decreases, and low-amplitude slow theta rhythms appear, equal in amplitude or exceeding the alpha rhythm. Behavior: drowsiness with half-asleep dreams, absurd or hallucinogenic thoughts, and sometimes with hypnagogic images (dreamlike hallucinations). Muscular activity decreases, the frequency of respiration and pulse decreases, metabolism slows down, and the temperature decreases, the eyes can make slow movements. At this stage, ideas can intuitively appear that contribute to the successful solution of a particular problem or the illusion of their existence. In EEG, sharp vertex waves, POSTS, can be recorded, hypnagogic hypersynchrony is rarely observed. Hypnagogic twitches may occur in this stage.
  • Second stage (shallow or light sleep). Further decrease in tonic muscle activity. Heart rate slows down, body temperature drops, eyes fixed. It takes a total of about 45-55% of total sleep time. The first episode of the second stage lasts about 20 minutes. Theta waves dominate in the EEG, the so-called “sleepy spindles” appear - sigma rhythm, which is a frequent alpha rhythm (12-14-20 Hz). With the advent of “sleepy spindles,” consciousness is turned off; it is easy to wake up the person in the pauses between the spindles (and they occur about 2-5 times per minute). Episodically sleepy spindles can be included in the structure of stages 3-4. Perception thresholds increase.
  • The third stage. Slow sleep. A stage is classified as 3rd if the delta oscillations (2 Hz) are less than 50% and the 4th stage if the delta is more than 50%.
  • Fourth stage. The deepest slowest delta sleep. Delta oscillations (2 Hz) prevail. The third and fourth stages are often combined under the name of delta sleep. At this time it is very difficult to wake a person; 80% of dreams occur, and it is at this stage that sleepwalking, night terrors, talking and enuresis in children are possible. However, a man remembers almost none of this.

In a healthy person, the third stage takes 5-8%, and the fourth stage is still about 10-15% of the total sleep time. The first four slow-wave sleep stages normally occupy 75–80% of the entire sleep period. It is believed that slow sleep is associated with the restoration of energy consumption. Studies have shown that it is the phase of slow sleep that is key to anchoring conscious “declarative” memories.

Fast sleep

Fast sleep (synonym: fast-wave sleep, paradoxical sleep, stage of rapid eye movements, or abbreviated BDG sleep, REM sleep). This is the fifth stage of sleep, it was discovered in 1953 by Kleitman and his graduate student Acerinsky. Fast sleep follows slow and lasts 10-15 minutes.

On the EEG, rapid fluctuations in electrical activity are observed, which are close in meaning to the beta waves of a sawtooth wave. During this period, the electrical activity of the brain is similar to the waking state. However, (and this is paradoxical) in this stage a person is in complete immobility, due to a sharp drop in muscle tone. However, the eyeballs very often and periodically make quick movements under closed eyelids. There is a clear connection between the BDG and dreams. If at this time to wake the sleeper, then in 90% of cases you can hear the story of a bright dream.

Electroencephalogram reflects the state of activation and is more like the EEG of the 1st stage of sleep. The first episode of REM sleep comes about 70-90 minutes after falling asleep, lasts 5-10 minutes. In the course of sleep, the duration of subsequent episodes of REM sleep increases, reaching several tens of minutes in the morning. In an adult, the proportion of the REM phase is about 20-25% of the total sleep time. The sleep phase from cycle to cycle is extended, and the depth of sleep decreases. Some of the interrupted fast sleep should be replenished in the following cycles.

It is assumed that fast sleep provides the functions of psychological protection, processing of information, its exchange between the conscious and subconscious.


During REM sleep, there is an increase in the secretion of adrenal hormones, an increase in cerebral blood flow, a change in heart rate, various forms of arrhythmias, elevations and drops in blood pressure, changes in breathing patterns, and erection of the penis or clitoris.

Sleep function

The visceral theory of sleep claims that in a dream the central nervous system is engaged in the analysis and regulation of the work of the internal organs.

  • Sleep provides rest for the body.
  • Sleep contributes to the processing and storage of information. Sleep (especially slow) facilitates consolidation of the material studied, fast sleep implements subconscious patterns of expected events.
  • Sleep is the body's adaptation to changes in light (day-night).
  • Sleep restores immunity by activating T-lymphocytes that fight colds and viral diseases.

25. Reducing pain threshold

Процессы, которые происходят с человеком во время сна

When the body is completely relaxed to the point of paralysis, the nerves cannot receive signals of pain and transmit them to the brain. It also explains why people hear bad smells, sounds, etc. during sleep.

The required sleep duration

The average duration of a person’s sleep usually depends on numerous factors: from age, gender, lifestyle, nutrition, and degree of fatigue, to external factors (general noise level, location, etc.). In general, for sleep disorders, its duration can range from a few seconds to several days.

There are also cases that an adult needs 12 hours to sleep with a supply of energy or to recover from hard work and sleepless nights. Sleep duration less than 5 hours (hyposomnia) or a violation of the physiological structure are considered risk factors for insomnia.

Sleep deprivation is a very difficult test. Within a few days, a person’s consciousness loses clarity, he feels an overwhelming desire to fall asleep, periodically “falls” into a borderline state with confused consciousness. This method of psychological pressure is used during interrogation, and is considered as sophisticated torture.


Recent studies of the functionality of dreams at the University of Helsinki (led by prof. En: Pekka Sutola) have shown that the REM sleep phase sometimes occurs quickly in mammals, and then they enter the deep sleep phase. This explains why epileptics have a REM-like phase during an attack and are unable to recall events several hours before the attack. More complete structure of the functioning of this system has not yet been established.

If we take 70 years for the average age, then one of them sleeps about 23 years.


The afternoon short rest-siesta is a historical element of the culture of many nations. Most often it is found in hot countries. A recent study conducted in Greece jointly by the University of Athens Medical School and Harvard showed that a half-hour afternoon rest at least three times a week reduces the risk of death from a heart attack by 37%.

Sleep pathology

With persistent sleep disorders, there are situations when a doctor’s intervention is necessary. In the news publications published several cases of many years of complete lack of sleep in humans.

  • Dissomnia - night sleep disorders, for example, insomnia (insomnia). Causes: neurosis, psychosis, organic brain damage (encephalitis, epilepsy), somatic diseases.
  • Sleep apnea - psychogenic or mechanical respiratory failure in a dream.
  • Hypersomnia - an insurmountable pathological drowsiness. Examples: narcolepsy, lethargic sleep.
  • Parasomnias - the reason: neurosis. Examples: somnambulism (sleepwalking / sleepwalking), teeth grinding, nightmares, epileptic seizures, etc.
  • Sleep paralysis is a condition where muscle paralysis occurs before falling asleep or after waking up.