Every day, after a hard day, each of us feels an irresistible need to take a horizontal position, relax and fall asleep. We spend almost a third of our lives in this state - in a state of sleep. Daily physiological sleep, like nutrition, is a basic need of the body.

Moreover, sleep deprivation is much more difficult for humans and animals to endure than lack of food. For the first time, M. Manasseina (1894) established that prolonged insomnia leads to death. Puppies die from insomnia on days 4-5. Adult dogs, completely deprived of food, lost 50% of their weight within 20-15 days, but they could be fattened, and they died from insomnia after

10-12 days with a decrease in body weight of only 5-13%.

Prolonged sleep deprivation is difficult for a person to tolerate. The speed of mental reactions decreases, mental performance decreases, and fatigue quickly sets in.

Sleep duration changes with age. The following sleep needs of people of different ages have been established: up to 1 year - 16 hours; 5 years - 12 hours; 12 years - 10 hours; 17 years and older - 8 hours.

In addition to physiological daily sleep, there are several other types of conditions that are similar in their external signs to sleep, and are also called sleep, although in fact the physiological mechanisms of their occurrence are completely different. These include: narcotic sleep, seasonal sleep(in animals that hibernate in winter or summer), pathological sleep, hypnotic sleep. We will talk about some of them in this lecture, but the main object of our study will still be physiological sleep.

Sleep structure. For a long time it was believed that after a short period of falling asleep, the human nervous system enters a state of inhibition for 7-8 hours. Then inhibition of the central nervous system gives way to excitation and the person wakes up. Thus, sleep and wakefulness periodically replace each other, and the main difference between sleep and a wakeful state is the diffuse inhibition of the cerebral cortex, which has a protective significance and restores the functioning of cells nervous system during sleep.

However, with the development of microelectrode technology and electrophysiological research methods, it became clear that during sleep, most nerve cells do not rest, but continue to work, only in a different, more synchronized mode. It turned out that the structure of physiological sleep is quite complex, and during the night there is a change of two phases or stages of sleep that are different in their physiological characteristics, which can be clearly limited using polygraphic recordings of EEG, ECG, and other physiological functions, including eye movements and skeletal muscle activity.

In physiological sleep of humans and animals, at least two phases are distinguished, designated as non-REM sleep phase (SWS) And REM sleep phase (REM)) . In the literature there are many designations for slow sleep (up to 14 names) and fast sleep (22 names). The most common synonyms for FMS are: synchronized, orthodox, slow wave, dreamless sleep (Non-Rem sleep). Rapid eye movement (REM) sleep is often referred to as desynchronized, paradoxical, diamond-brain, and dream sleep (Rem sleep).

It has now been shown that the period of wakefulness is replaced by a stage of slow-wave sleep, which lasts 60-90 minutes and passes into the stage of rapid sleep (5-10 minutes). Then slow-wave sleep begins again. So they replace each other during the night, and the depth of the FMS gradually decreases and the duration of the FBS increases. Thus, the structure of sleep can be expressed as follows:

Wakefulness - FMS (60-90 min) - FBS (5-10 min) - FMS (60-90 min) - FBS 10-15 min) - FMS (60-90 min) - FBS (15-20 min) - FMS (60-90 min) - FBS (20-25 min) - FMS (60-90 min) - FBS (25-30 min) - waking up.

In healthy people, 4-6 completed cycles (FMS + FBS) occur per night. It should be noted that the deepest stage of slow-wave sleep is normally most clearly represented in cycles 1 and 2. Slow-wave sleep occupies 75-80% of the duration of physiological sleep in an adult, and fast sleep - 20-25%. In a newborn

the share of FBS accounts for more than 50%, in a child under 2 years old - 30-40%. From the age of 5, the FMS and FBS ratios characteristic of adults are formed.

NREM sleep includes a number of behavioral and electroencephalographic signs that can be recorded starting from the moment of immersion in sleep. There are 5 stages of falling asleep.

Stage A behaviorally characterized by a transition from relaxed wakefulness to drowsiness. At this time, the EEG shows an alpha rhythm with varying amplitudes.

Stage IN - nap .- characterized by a flattened EEG curve with the absence of an alpha rhythm (5-6 Hz), layering of the theta rhythm (2-3 Hz), and individual delta oscillations. Before the transition to the next stage C, sharp waves lasting 0.2-0.3 seconds with an amplitude of 100-200 μV (vertex potentials) are often recorded. On the EOG in stages A and B, slow eye movements are recorded (one movement takes 1-2 seconds). During sleep, the EMG shows a slight decrease in amplitude compared to wakefulness.

Stage WITH - light sleep .. At this time, the so-called “sleepy spindles” - oscillations with a frequency of 14-16 Hz, an amplitude of 30-50 μV and higher, organized in a series that outwardly resembles the shape of a spindle. The appearance of K-complexes (two or three phase waves lasting 0.5-1 seconds) is typical. Slow, low-amplitude oscillations in the delta (0.5-1 Hz) and theta range, and less frequently fast rhythms, continue to be recorded. On the EOG, slow eye movements decrease or completely stop. The EMG shows a further decrease in the amplitude of muscle biopotentials.

Stage D - dream medium depth . . Higher amplitude (80 µV) delta waves appear on the EEG against the background of sleep spindles. There is a tendency for the number of sleep spindles to decrease and the number of delta waves to increase. There are no slow eye movements on the EOG, the EMG pattern is the same as at stage C, or an even greater decrease in the amplitude of muscle biopotentials is observed.

Stage E - deep sleep. . The EEG is dominated by high-amplitude (up to 200 µV) slow (0.5-1 Hz) delta waves with the disappearance of sleep spindles and K complexes. Low-amplitude activity of various frequency ranges can be recorded, layered on delta waves. There are no eye movements on the EOG; on the EMG, the amplitude of the potentials is maximally reduced.

In addition to the indicated shifts in the EEG, EOG, EMG, during slow-wave sleep there is a decrease in the intensity of all autonomic functions.

REM sleep is characterized by a complete lack of activity in the muscles of the face and neck (in other muscles there is no significant change in tone compared to the deep stages of slow-wave sleep), the appearance of rapid eye movements (REM) on the EOG, single or grouped in packs, each lasting 0.5-1 .5 sec. On the EEG, the picture corresponding to stage B can also be recorded by the alpha rhythm. There is an irregularity of vegetative indicators, which is designated by the term "vegetative storm" - the frequency of breathing and heartbeat changes, there is an increase in gastrointestinal motility, an increase in blood pressure, and the release of hormones. Below we will talk about this in more detail.

Despite the EEG picture, which is close to drowsiness or a state of wakefulness, according to behavioral indicators, REM sleep is deep, and it is no easier to awaken a person from this stage than from deep slow-wave sleep. When awakening from REM sleep, the vast majority of people report vivid dreams.

State of the vegetative sphere during sleep. . Registration of autonomic functions is one of the simplest and at the same time quite informative methods for objective sleep research. Just one observation of breathing or hemodynamic parameters allows one to judge with sufficient certainty the phase of the wakefulness-sleep cycle. Large number interesting observations on the state of the vegetative sphere during sleep are given in one of the world's first monographs on the physiology of sleep by M. Manasseina (1892). The thesis put forward by Manasseina that “during sleep only consciousness in a person ceases, all other functions, if not strengthened, then in any case continue,” with some clarifications is still valid today, especially when applied to the vegetative sphere.

Respiratory system . . Significant changes in the external respiration system begin already in the drowsiness phase. Against the background of slow breathing, periods of respiratory arrhythmia appear. It varies according to the hypopnea, polypnea, apnea type, and at times has the character of periodic Cheyne-Stokes or Biot respiration. Such phasic changes in breathing are central in nature and coincide with periods of sleep spindles. Reflex influences emanating from internal organs also play a role in changes in breathing during sleep (apnea was noted at the onset of an episode of nocturnal enuresis).

The respiratory rate in stage C decreases compared to drowsiness. Pulmonary ventilation does not change, which is achieved by increasing the breathing amplitude. In stages D and E, the breathing of healthy people is regular, slower compared to wakefulness, but can be more frequent than in stage C.

Cardiovascular system . . A slower heart rate, lower blood pressure, and slower blood flow have long been considered constant signs of natural sleep. Modern research confirm that during the transition of an animal or person from wakefulness to FMS, these shifts take place. Moreover, if in shallow stages of FMS these indicators are constant, then in stages B and C fluctuations in blood pressure and pulse rate are noted. Blood pressure changes during the transition from one stage of FMS to another. In the superficial stages of FMS, the dependence of the pulse rate on the breathing phase is clearly revealed, while in the deep stages it disappears. The decrease in blood pressure in the FMS depends more on a decrease in heart rate than on a decrease in stroke volume.

With the onset of FBS, pronounced changes occur in a person’s cardiovascular system: the pulse quickens and becomes arrhythmic, extrasystole appears, the average value of blood pressure increases, and the IOC increases. During sleep, cerebral blood flow changes significantly - in the FMS it decreases, in the FBS it increases.

Temperature, sweating and other autonomic functions . Brain temperature, like other autonomic indicators, quite naturally follows the level of wakefulness and the nature of sleep. During the transition from wakefulness to FMS, it decreases, during FBS it increases, and often to higher numbers than during wakefulness. Researchers disagree on the explanation for this fact. Saton and Kamamura believe that main reason This phenomenon is an increase in brain metabolism in the FBS. Abrams showed that the increase in brain temperature in the FBS depends on its warming by flowing blood. It is possible that both of these mechanisms are at work.

Naturally, temperature cannot change outside the brain. During night sleep, body temperature decreases in women to an average of 35.7 o C, in men - to 34.9 o C.

There is a certain dynamics of sweating during sleep. During the relaxation period before sleep, there is a short decrease in sweating on extrapalm surfaces, which after falling asleep increases in proportion to sleep in the FMS. This is consistent with evidence that 90% of sweat is produced before the minimum daily temperature is reached. Sweating on the palms changes in the opposite way. Here it stops after falling asleep and is absent throughout sleep until the moment of awakening.

This difference is explained by the different meaning of local sweating. It is believed that psychogenic sweating occurs on the palms, which is regulated by cortical areas, and thermogenic (extrapalm) sweating has a central representation in the hypothalamic region.

When FBS occurs, sweating decreases sharply. Against the background of such a decrease, bursts of perspiration are sometimes observed, and upon awakening at this moment, the subjects reported an exciting dream. If the subjects were woken up after the end of the FBS, then the report of emotionally rich dreams occurred when the same phasic increase in sweating was recorded. In cases where this was not the case, subjects were unable to remember the dream or reported emotionally indifferent dreams. A tonic decrease in sweating is observed when the ambient temperature increases.

Another vegetative indicator of the nature of sleep is the width of the pupil and the state of the nictitating membrane of animals. Being constricted in the FMS, the pupil periodically dilates and the nictitating membrane contracts in the FBS.

Analysis of gastric motor activity and acidity gastric juice revealed changes in these parameters during sleep. The studies were carried out using radiopills. Motor activity of the gastrointestinal tract decreases in FMS and increases in FBS. All subjects had large stomach movements during the 4th hour of sleep at night. They continued to intensify in the second half of the night. The pH values ​​of gastric juice during sleep range from 0.5 to 3.0, thus demonstrating an increase in acidity compared to wakefulness. This explains the characteristic night pain in patients with gastric and duodenal ulcers.

Among other vegetative manifestations, it should be noted the occurrence of penile erection in the FBS, even in those men who consider themselves impotent. This phenomenon is often evidence of the functional nature of impotence.

Mechanisms of dreams.. As noted above, in the REM sleep phase

active mental creative activity of neurons. Almost all people see dreams, but not everyone remembers them (at least 80%). Even intrauterine dreams are recognized. Dreams are also common to animals. The presence of dreams is confirmed not only by the stories of awakened people, but also by the movement eyeballs, which are recorded only during REM sleep. It all depends on what phase of sleep a person wakes up in. If he wakes up in the REM phase, he remembers them and can verbally reproduce them, but if he wakes up in the NREM phase, then, as a rule, he does not remember them. Moreover, some scientists believe that if a person does not see dreams, this can lead to various functional disorders of the nervous system such as neuroses.

If in an experiment, people are awakened for many days in the slow-wave sleep phase, this does not lead to disruption of the functions of the nervous system. If they are constantly awakened in the REM sleep phase, this causes a disorder of the nervous system. In this regard, some scientists believe that dreams are one of the mechanisms for overcoming various life obstacles: in stressful conditions, they help restore mental balance, and also prepare the body for the upcoming struggle. Thus, dreams should be considered as a protective mechanism that protects the body from the effects of certain harmful factors. environment, which can lead to the development of various pathological conditions.

The nature of dreams depends on a combination of many factors. In most cases, they correspond to life situations and reflect actual events. However, in some cases they do not wear vital character. At one time I.M. Sechenov said that the brain in a state of sleep represents probable events in incredible combinations (“Dreams are unprecedented combinations of experienced impressions”). This once again indicates the active creative activity of neurons during sleep. The nature of dreams is determined by several factors, which include the following:

1. Environment, including sound, light, temperature and other stimuli. So, if the ambient temperature changes, then this affects the nature of dreams: a decrease in temperature in dreams is manifested in what he dreams: that his person is immersed in an ice hole, etc.

2. Condition internal environment body. As is known, in a state of sleep, information from internal organs can “break through” into the cerebral cortex, which affects the nature of the dream, about which much is written in Kasatkin’s monograph. So, for example, if headaches occur during sleep, then the sleeper dreams that they are hitting him on the head or trying to open the skull. If there is pain in the gastrointestinal tract, then dreams are manifested by autopsy abdominal cavity etc. Kasatkin, in this regard, draws the reader’s attention to the fact that in some cases such dreams can be a harbinger of some disease and doctors should pay attention to such dreams.

3. The nature of the dream to some extent depends on the thoughts with which a person goes to bed. It was in this case that some discoveries were made, which were noted above.

Purpose of sleep. There are several theories explaining the purpose and biological significance sleep. First of all, it should be said about the theory of restoring the functionality of nerve cells. It was believed for a long time that night sleep has exclusively protective significance, it is needed for the rest of nerve cells that work intensively during wakefulness. This point of view was held by I.P. Pavlov and many other scientists. However, with the development of physiological science and the discovery of sleep phases, it became clear that during sleep, nerve cells do not rest, but work differently.

Therefore, currently the so-called most accepted all over the world. And informational sleep theory. Now it has become clear that sleep is a special way organized activity brain, aimed at processing information received during wakefulness.

The main difference in the mechanisms of organizing the activity of the nervous system during sleep is the greater synchronization of the work of individual nerve cells, especially during FMS. It has been shown that in the REM sleep phase, the activity of the nervous system in processing information increases, and certain manifestations of this activity reach the sphere of consciousness and can be included in the fabric of dreams.

What does it mean to process information accumulated while awake? Firstly, part of the information that a person’s brain had stored until this moment must simply be forgotten, excluded from memory (for example, the fact that it was necessary to come to a lecture today). Another part of the information is stored in the mechanisms of long-term memory, while corrections and additions are made to the memory matrices in accordance with the new information. The third part of the information is embedded in the personality structure and influences the formation of a person’s character and the characteristics of his behavior in specific conditions. The fourth part of the information is involved in the construction functional systems purposeful behavior of a person after waking up, etc.

As you can see, there are quite a lot of information processing channels. In a dream, an emotional restructuring of a person also occurs, which is well noted even in folk wisdom, summarized in sayings and proverbs (“to sleep with grief, there will be no grief”, “the morning is wiser than the evening”, etc.)

Evidence that sleep is associated with creative information processing activity is widely known facts solving a problem that tormented a person in a dream. It is known that Mendeleev saw the final version of his Periodic Table of Chemical Elements in a dream, many mathematicians received solutions to complex problems in their dreams, many poets, upon waking up, wrote down the beautiful poems they dreamed of, Kekule discovered the benzene ring; Toscanini - fragments of musical works, etc.).

It is important that this information resulting from the night creative work, was recorded immediately after waking up, since it usually completely falls out of memory within 5-10 minutes after sleep. This is why many people believe that they never dream. They just don't remember them.

Theories of the origin of sleep and its neural mechanisms.

Since ancient times, scientists have tried to explain the mechanisms of sleep. There were so-called humoral theories, which main role the development of sleep was attributed to one or another humoral factors (lactic acid, cholesterol, neurotoxins, hypnotoxins, etc.). However, after fundamental works P, K. Anokhin on Siamese twins who had common system blood circulation, but fell asleep in different times, interest in humoral theories has waned, although it is recognized that changes in the concentration of various humoral agents can alter the excitability of nerve cells and promote (or prevent) the onset of sleep.

In the laboratory of I.P. Pavlov, around 1909, began intensive development of questions about the mechanisms of sleep. The dream stopped Pavlov's attention because it interfered with his work with conditioned reflexes. As soon as the experimenter began to develop various types of cortical inhibition, the dog naturally fell asleep. This prompted us to make sleep the subject of a special study, the results of which were presented in the article “Internal inhibition and sleep are the same process in its physicochemical basis.”

According to Pavlov's theory, sleep is a diffuse generalized inhibition that covers the entire cortex. The starting point from which the irradiation of inhibition occurs is necessarily located in the cortex. According to Pavlov, sleep is a cortical phenomenon in its very essence.

However, evidence soon appeared that decortication does not change the pattern of alternation between sleep and wakefulness. These data forced Pavlov to suggest that the subcortical regions are also involved in depression only in the absence of the cortex. Sleep induced from the subcortex was not given the importance of a normal mechanism, and not a single experimental study was devoted to it in Pavlov’s laboratory.

The first evidence of the participation of the hypothalamus in sleep mechanisms comes from the Viennese psychiatrist and neurologist Mautter, who in 1890 noted the symptom of drowsiness when the area of ​​the bottom of the third ventricle is affected. After the so-called epidemic "lethargic encephalitis" 1917-1921 In Europe, Economo suggested that in the area of ​​the bottom of the third ventricle there is a sleep center (Economo's center).

Progress in the study of neural mechanisms of sleep is associated with the development of microelectrode research techniques. The experiments examined the activity of neurons during REM and NREM sleep, as well as during wakefulness. It was possible to detect an increase in spike discharges in brain neurons in large areas of the visual and parietal cortex, thalamus, reticular formation and other structures. These data emphasized the active nature of the processes occurring in the nervous system during sleep.

In 1928, Hess showed the possibility of obtaining sleep by electrical stimulation of the diencephalic region - a fairly large area lying between the Vic d'Azir bundle and the Meyer tract, as well as from the middle and partly ventromedial hypothalamus.

Currently, there are three groups of experimentally obtained facts that are important for the construction of a unified neural theory of sleep:

1) irritation of certain diencephalic structures gives sleep;

2) cessation of the activating effect on the part of the reticular formation - the ascending activating system of the Russian Federation - causes a decrease in cortical activity and promotes the development of sleep;

3) the occurrence of long-term or particularly strong processes of internal inhibition in the cortex leads to the development of sleep.

The modern theory of sleep development considers sleep as the result of certain cyclical changes in the relationship between the cortex and the most important subcortical formations, and, in particular, the hypothalamus and the RF region of the brain stem. According to this theory, in a state of wakefulness, the cortex, and in particular its frontal parts, inhibits the activity of the so-called “Hess center,” which is responsible for the development of sleep. The Hess center is capable of inhibiting the activity of the reticular activating system either at the level of the medulla oblongata or at the level of the thalamus, but since it itself is inhibited by impulses from the cortex during wakefulness, this does not happen, and under these conditions the RF activates the cortex, which further contributes to the suppression of activity center of Hess.

The sleep state is characterized by the release of the Hess center from the inhibitory influence of the frontal cortex, which leads to suppression of the reticular activating system and a decrease in cortical activity, which results in the occurrence of sleep. This release of the Hess center can be either a consequence of a decrease in the inhibitory influence of the cortex, or a consequence of the activation of the Hess center, under conditions when the previous level of cortical impulses is not enough to suppress the intrinsic activity of the hypothalamus.

In addition, it can be assumed that in this case the activating effect of the RF is suppressed, as a result of which cortical activity decreases and the amount of inhibitory impulses to the Hess center decreases, which leads to its release. It follows that the effect on the central nervous system of various narcotic substances, although it causes the same effect of narcotic sleep, can in essence be extremely diverse in the mechanism and place of its effect. In other words, different drugs have different points of application in the central nervous system.

In order for sleep to occur, the hypnogenic zone must be activated. Factors that contribute to its launch include:

1. The onset of a certain time, which is triggered on the principle of a conditioned reflex reaction (possibly like a biological clock). If a person goes to bed at the same time, then when this time comes, the urge to sleep appears, even during the daytime.

2. Change in the temperature of the internal environment of the body - in the evening, as is known, the blood temperature rises slightly, which contributes to the stimulation of the hypnogenic zone.

3. In the evening, there is information overload, which is a factor that triggers sleep.

4. By the end of the day, numerous humoral factors (specific neuropeptides, metabolic products, many mediators) accumulate in the blood, stimulating hypnogenic structures.

5. Before going to bed, the effect on the body of various environmental irritants is significantly reduced (lights turn on, sound stimuli stop), which contributes to the excitation of the system that organizes sleep.

6. Great value attached to sleep rituals (the appearance of a clean bed, etc.). However, if a person has not slept for a long time, then in this case the main importance is attached not to the external factors that ensure sleep, but to changes in the internal environment of the body, and he instantly falls asleep, not paying attention to the current stimuli of the external environment of the body.

At the end of sleep, the system that organizes wakefulness is launched, and great importance is attached to such factors as:

1) Conditioned reflex awakening (time triggered).

2) Environmental stimuli are turned on - sound, light and others.

3) Sleep factors disappear from the blood (metabolites, mediators, neuropeptides are destroyed).

4) Blood temperature decreases.

5) Information overload ceases to operate, since information during sleep is sorted into its own blocks.

Pathological sleep.

Of all the neuropsychic phenomena that have long caused and still cause superstitious rumors, night sleep and dreams are the most common. Incomparably less common are other types of sleep and twilight states of consciousness, which manifest themselves mainly in hysterical patients. This includes lethargy- incessant pathological sleep, which can sometimes last without interruption for many days, weeks and even years. In this case, not only voluntary movements, but also simple reflexes are so suppressed, the physiological functions of the respiratory and circulatory organs are so reduced that people who have little knowledge of medicine can mistake the sleeping person for the dead.

The cause of such sleep is damage to the nervous structures responsible for sleep - an example would be lethargic encephalitis, when inflammation is localized in the diencephalic region (Hess center).

Sleepwalking.. Another type of pathological sleep has long been known, called sleepwalking, sleepwalking or natural somnambulism. A healthy person can dream that he is going somewhere or doing some work, while remaining motionless. The sleepwalker, continuing to sleep, leaves the bed and takes a walk or automatically

does the job he dreams about. Having completed his task, he returns to bed, sleeps peacefully until the morning, and when he wakes up, he remembers nothing about his nightly adventures. The reason for this kind of pathology lies in violations of the cortical mechanisms of sleep.

Hypnotic sleep. One of the types of sleep is artificial sleep - hypnosis, which is directly related to medicine, which is often used by doctors as a remedy. During artificial sleep, the doctor makes suggestions to the patient, counting on a therapeutic effect. In order to induce a hypnotic state, the doctor must apply those facts that trigger the system that organizes sleep. It should be remembered that hypnosis differs from natural sleep in that, firstly, in the cerebral cortex one excited area of ​​the brain is stored in the second signaling system, through which there is contact between the hypnotized person and the doctor (“rapport”). Secondly, in hypnosis there is no paradoxical sleep.

To induce artificial sleep and trigger the hypnogenic system, it is necessary to imitate sleep conditions. To do this, first of all, it is necessary to exclude environmental irritants - the room must be isolated from external noise and other irritants, darkened, the patient must be in a chair, and relax as much as possible. You should use some monotonous weak stimulus, for example, the sound of rain. The doctor’s communication with the hypnotized person is of great importance - an affectionate, quiet, gentle, at the same time, suggestible voice. It is recommended to use light stroking of the body. It is good to focus the patient’s attention on some object - a shiny ball, for example, and remember that in immersing a person in hypnosis, a large role belongs to a conditioned reflex reaction to time: if he does not fall asleep in the first session, then he will certainly do so in subsequent ones, i.e. .To. he wants to be cured.

The speech formula of verbal suggestion necessarily contains a description of those physiological changes in the body that accompany falling asleep: “your eyelids are drooping, you want to sleep, your hands are getting heavy, ....... etc.” All this helps to quickly cause the appearance of a focus of inhibition in the cortex, which triggers the sleep organization system. After immersion in hypnotic sleep, the patient is instilled with those ideas that he must internalize as his own beliefs - for example, about the dangers of smoking.

This process and its physiology are very interesting information, which you can find in this article.

Introduction

Every person is familiar with such a state as sleep. However, not everyone understands its physiology. But from birth, from the first minutes of life, a person sleeps, and in childhood we sleep most of our time, but as we grow older, we significantly increase the period of wakefulness. However, for every person, even an adult, it is difficult to find a more attractive activity than sleep. Types of sleep depend on many factors, so we will talk about them below. It's no secret that a person spends about a third of his life in the kingdom of Morpheus, so since the beginning of civilization people have been trying to figure out what happens to the human body in a dream.

Ancient civilizations believed that when a person falls asleep, his soul is transported to some distant parts of the world, so sometimes it is very difficult to distinguish between reality and dream. Many people are also convinced that dreams have secret meaning, so it is very important to solve them correctly.

What is sleep?

Let's look at what sleep is from a physiological point of view. This condition is characterized by periodic recurrence. While in a dream, a person reacts very poorly to external stimuli, since the activity of everyone is vital important processes slows down significantly.

Today, scientists have come to the conclusion that human body there are two various systems, responsible for sleep and the state of wakefulness. The first of them is called hypnogenic. It is she who is responsible for the depth of sleep, as well as its duration. In fact, such a system is very complex and includes many small subsystems. What's happening in it psychological processes are a consequence biological rhythms. As you can see, “sleep” is not a very simple concept.

Types of sleep

Scientists have created a classification that includes several types of sleep. First of all, you should pay attention to physiological sleep. This state of living organisms is mandatory. Physical or natural sleep is characterized by a certain periodicity.

Each person has his own sleep pattern. For example, most people sleep at night and are awake during the day. But there are also exceptions. Animals do not adhere to such rules. They usually sleep several times a day (depending on the species). Let's consider what types of dreams exist, besides physiological ones.

Narcotic and hypnotic sleep - types of sleep caused by artificial influence

Sleep caused by the influence of various chemical substances on the brain is called narcotic sleep. In this case, its duration and depth depend on the properties and portions of the medications used. Typically, a person enters such a sleep immediately before undergoing surgery.

Hypnotic sleep is also artificial. In this case, a specially trained person, a hypnotist, will use special movements or words to put the person into a sleepy state. In this case, some nerve centers of the brain are inhibited. First of all, such a dream affects the part of the human brain responsible for mental operations. Usually, such a dream is used for people who have pathological abnormalities.

Sleep disturbance

Sleep disorders (we will definitely consider their types) are also called pathological sleep. Let's consider what types of such pathologies can be found.

The first thing you need to pay attention to is insomnia. It occurs as a result of taking certain drugs, alcohol, coffee, and can also appear under stress and with certain disorders of brain function. All of the above factors prevent a person from getting enough sleep, which means his brain stops functioning properly.

In very rare cases, a condition such as lethargic sleep. In this case, all vital processes of the body are significantly inhibited, and at first glance one may think that the person has died. In such cases, the person does not need food and does not react to external stimuli (including pain). Such a dream is very deep. The patient can fall into this state for either a few hours or several years. The lethargic state may be caused by some kind of disease, stressful condition or significant fatigue.

But sleepwalking is a fairly common phenomenon and at the same time very dangerous. A person can do different things in a dream, without absolutely remembering how he does it. Most often, this condition occurs in cases of overwork of the nervous system or as a result of brain injuries. Unconscious wakefulness is a very dangerous state not only for the person himself, but also for those around him. Therefore, if you have noticed such a pathology, be sure to tell your neurologist about it.

Natural dreams

Types of physiological sleep are a very interesting and fascinating topic that every person should become familiar with. Everyone is capable of dreaming naturally from time to time, and it's actually a wonderful thing. Let's look at some types of natural dreams that are most often present in our lives.

• Natural healthy sleep, capable of fully or partially reflecting existing reality.
• Visions. Some people during sleep see pictures that they encounter in reality.
• Predictions. Often, upon awakening from sleep, we feel some worry about ourselves or our loved ones, and, as a rule, such worries come true. If you have such dreams, then this is a warning of impending danger.
• Dreams. This state is characterized by images that a person saw in real life, and they were reflected in his dream.
• Night visions of a ghostly nature are characterized by the frequent appearance of the same images in a dream.

NREM sleep

Sleep (types and phases of sleep are discussed in this article) is divided into phases into slow and fast. Typically, the slow phase begins with a nap that lasts about fifteen minutes. After dozing, light sleep begins, which is characterized by insignificant depth. At this stage, the ear canal is particularly sensitive, so it is very easy to wake a person. After this, the period of falling asleep begins, and the person plunges into sound sleep. The slow phase usually lasts about an hour. At this time, a person sees dreams that in the morning he cannot remember.

It is this phase that is characterized by sleepwalking and the ability of a person to speak in his sleep. However, his speech will be incoherent and incomprehensible. It is this phase that is very important for a person, since during it the body restores its strength. If the slow phase is deliberately interrupted, then in the morning the person’s condition will be very bad.

Fast phase

During this phase, a person’s muscle tone decreases, heart rate slows down, and blood pressure. At the same time, the brain becomes very active. It is in this phase that a person is able to see very vivid and memorable dreams. If you wake up during this phase, the person will feel cheerful and energized.

At this time, the nervous system begins to recover and the information received during the day is analyzed. In this case, phases of REM sleep can appear several times a night.

The meaning of sleep for a person

The type of sleep a person has depends on many factors. For example, from his emotional state or the use of certain chemicals. In order to be healthy and feel good, you need to figure out how many hours it is better to spend sleeping.

As is known, than older man becomes, the less time he needs to sleep. For example, a newborn baby needs to sleep about twenty-two hours a day for normal functioning. But for one-year-old children, fourteen hours is enough. The types of sleep patterns depend not only on the baby himself, but also on his mother. For example, if a mother goes to bed late, the child will adapt to the same routine and will also go to bed late.

For children aged three to seven years, twelve hours of sleep will be enough. In this case, it is better to divide it into night sleep and afternoon sleep. For schoolchildren who have reached the age of ten, ten hours of night rest will be enough. But for adults optimal time for sleep is seven to eight hours.

Types of sleep, physiology - this is information that will help every person understand themselves. After all, our emotional and physical health depends on how we sleep. Therefore, please pay attention to this issue special attention. Be healthy and take care of yourself.

The following types of sleep are distinguished:

Periodic daily allowance;

Periodic seasonal;

Hypnotic;

Narcotic;

Electrosleep;

Pathological.

The first three types of sleep are physiological. Periodic daily sleep lasts for an adult about 8 hours on average. In childhood, the duration of sleep is longer; in old age, the duration of night sleep decreases, but the periods of drowsiness and daytime sleep increase. Periodic seasonal sleep (hibernation) occurs during the cold period of the year in hibernating animals, as a protective adaptive reaction of the body developed by the species to the influence of unfavorable environmental factors.

In northern and temperate latitudes, with the onset of winter cold, invertebrates, fish, amphibians, reptiles and some species of mammals (marmots, bears, etc.) fall into a state of torpor. In burrows, under the bark of trees, in moss, in the ground and other shelters, they spend several months in this state. Some species of animals just as regularly fall into a state of torpor during periods of summer drought.

In this state, all metabolic processes occurring in the animal’s body slow down sharply. Being in a deep stupor, they naturally cannot eat, and their life is supported only by the reserves of nutrients accumulated in the body before hibernation in the form of fat and other reserves. The possibility of animals existing in hibernation without food for a long period (sometimes up to 6-8 months) is one of the amazing aspects of this phenomenon. No less interesting are other features of hibernating animals. In a state of torpor, they endure unfavorable conditions that cause death in other animals. For example, mammals that hibernate tolerate cooling of the bulk of their body to a temperature of -50.-70C, while animals that do not hibernate usually die when their body cools several degrees below normal. Insects and other invertebrates are even more resistant to low temperatures. In a state of torpor, animals can tolerate a lack of oxygen, the effects of many poisons, and infection with deadly diseases without harm to the body.

This regular fall into a state of hibernation and all the features associated with it also leave an imprint on the behavior of animals in active period their lives. Narcotic (from the Greek nárkōsis - numbness) sleep is caused by drugs and substances that poison the nervous system. Anesthesia is an artificially induced sleep, accompanied by loss of consciousness and sensitivity, relaxation of skeletal muscles (relaxation) and loss of exteroceptive reflexes. Anesthesia in veterinary and medical practice is used for various surgical operations, for examination and treatment of animals. There are deep and superficial anesthesia (stunning), pure or single-component (only one narcotic substance is used), combined (administration of two or more substances in different ways), mixed anesthesia (administration of a mixture of two or more drugs in one way) and combined (anesthesia is combined with local anesthesia), inhalation and non-inhalation. Electrosleep is caused by the action of direct electric current on certain areas of the brain. Pathological sleep occurs with age-related changes in the brain, disturbances in its blood supply, tumors, etc. A distinction is made between lethargic sleep, or imaginary death, and somnambulism, or sleepwalking.

Lethargic sleep occurs when the nervous system is exhausted, after difficult experiences, difficult childbirth, etc. This is more common in hysterics. A state of immobility, reminiscent of sleep, is the result of the spread of deep inhibition, involving the subcortical centers. This painful condition occurs in people as a result of various diseases. The longest lethargy was observed in Nadezhda Lebedina. In 1954, after a family quarrel, 34-year-old Nadezhda fell asleep and woke up only in 1974, having slept for two decades. 19th summer Maria Tello from Argentina, shocked by Kennedy's death, fell asleep for 7 years. Sometimes lethargy can be so similar to death that before the advent of medical equipment that recorded even minimal manifestations of vital activity, it also happened that people who fell into it were simply buried. That is why in America, for many years, coffins with built-in air ducts were in high demand, as well as special buttons, with the help of which, if you unexpectedly woke up in the family crypt, you could sound an alarm. And in less technically developed countries, cauterization of the dead with a hot iron was practiced - it was mistakenly believed that this could awaken those who had fallen into lethargy.
Somnambulism is also one of the manifestations of nervous system disorders. More often this happens in childhood after strong mental experiences or when the nervous system is unstable. By the time of puberty, these phenomena usually disappear. The essence of somnambulism is that when the cortex is inhibited cerebral hemispheres the motor centers become excited, which causes crying out at night, speaking or walking in sleep.