Sleep and wakefulness. Mechanisms of sleep and wakefulness of the body. Sleep as a special activity of the brain. Theories of sleep. Modern ideas about the nature of sleep. The value of sleep. Violation of the cycle "sleep-wake
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The current perceiving, regulating, coordinating and controlling activity of the human brain is constantly carried out against the background of various states.
- At one end of the spectrum of these states is active wakefulness
- On another - deep dream.
Brain rhythms significantly different in different states. The main contacts with the outside world are made by the person in a state of wakefulness, which is characterized by a level of brain activity sufficient for active interaction with the external environment. The electrical activity of the brain during wakefulness is characterized by desynchronization, it presents various rhythms of the brain, mainly in the range of 8-40 Hz.
States of wakefulness
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In maintaining waking statesthe internal area of \u200b\u200bthe pons, pons and midbrain, the reticular formation, is involved. This is proven in animal experiments. The fibers from these areas of the brain go to the non-specific nuclei of the thalamus and further to the cortex. Electrical stimulation of the reticular formation causes desynchronized electrical activity in the cerebral cortex. This is reflected in the increase in the encephalogram of its high-frequency components. Desynchronization is also observed with electrical stimulation of the reticular formation during sleep of the animal.
Two groups of cells with different chemical mediators are concentrated in the structures of the pons. In the blue spot, these are noradrenaline-containing neurons, and in the dorsal nucleus of the suture are gray-tonin-containing neurons. Both those and other groups of cells are most active during wakefulness - they are systematically discharged with a different rhythm. During deep sleep, these neurons are inactive - their pulse activity is very rare or completely absent. The excitation of neurons of the blue spot is always associated with the impact on the body of sensory stimuli of any modality (visual, auditory, tactile), especially new, unfamiliar stimuli. These neurons are active during periods of heightened response to the environment. That is, during periods of behavioral manifestations of attention (alarm, turning in the direction of the object of attention, smelling, etc.). A lack of serotonin in the blood leads to prolonged wakefulness, an increase in serotonin - to falling asleep, and an increase in the content of norepinephrine - to awakening. When the blue spot is damaged, the neurons of which produce norepinephrine, the animals sleep much longer than normal.
Most of the day a person is in a state of wakefulness, however degree of attentionto the surrounding events while cyclicallyis changing.The cycle of fluctuations of attention is 90-100 minutes.
Sleep Condition
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Sleep- a specific state of the brain and the organism as a whole, characterized by substantial immobility, an almost complete absence of reactions to external stimuli, phases of electrical activity of the brain and specific somatovegetative reactions.
The onset of sleep is accompanied by a decrease in response to external sensory stimuli, although the electrical manifestations of their action — evoked potentials — are recorded at all stages of sleep. Changes in the reactivity of the body during sleep are associated with many factors: a decrease in the sensitivity of the peripheral parts of sensory systems; blockade of afferentation at the thalamic level, a decrease in the excitability of the central parts of the brain due to a decrease in the influence of the cortex on the reticular formation, because activity of centrifugal paths is reduced, partial blockade of effectors, etc.
Sleep phases
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Sleep phasesdistinctly appear on the electroencephalogram and are repeated approximately with an hour and a half cyclical nature (Fig. 17.5).
Fig.17.5. EEG of the person in the period of wakefulness and sleep.
A - waking, eyes open, eyes moving;
B - various phases of sleep:
1 - alpha waves (8-12 Hz) prevail,
2 - tetta-waves (3-7 Hz),
3 - higher frequencies are poked (12-15 Hz),
4 - delta waves (0.5-2 Hz),
5 - paradoxical sleep phase with fast eye movements (REM sleep) and desynchronized electrical activity of the brain.
- At rest in a person with closed eyes, an alpha rhythm appears, in which the frequency of the waves of electrical activity of the brain is concentrated in the region of 8-12 Hz.
- After falling asleep the amplitude of the electrical activity of the brain decreases, and the basic rhythm (8-12 Hz) slows down to 3-7 Hz (theta waves).
- While deepening sleep Against the background of slow low-voltage activity, higher-voltage electrical oscillations with a frequency of 12-15 Hz appear. This is the so-called sleepy spindles.They occur periodically and last no more than 1 second.
- With further deepening of sleep high-amplitude low-frequency oscillations of 0.5–2 Hz (delta waves) begin to prevail. The deepest phase of sleep is accompanied by a change of delta waves to fast low-amplitude oscillations, similar to those that characterize the waking state.
- In the last deep phase of sleep there are rapid contractions of the eye muscles.
Many autonomic and motor indices change during sleep.characteristic of calm wakefulness. Metabolism energy decreases, pulmonary ventilation, pulse rate, body temperature, electromyogram amplitude, muscle tone, spinal reflexes decrease. Increases blood flow in the brain. All changes are cyclical, the most significant vegetative changes occur during paradoxical sleep. The constant companion of this stage of sleep - short-term coordinated subtle motor reactions - facial expressions, the movements of the fingers and toes, the movement of the eyeballs.
The vegetative indices that acquire the characteristics of the wakeful state in the paradoxical sleep phase also change: blood pressure increases, heart rate increases, skin resistance increases, etc. This is a phase of deeper sleep in which all the muscles of the body, except the eye, are relaxed. If a person is awakened in the middle of this phase, he will say that he has had a dream. Therefore, deep sleep with fast eye movements is considered a period of dreams, however, a direct link between dreams and eye movements has not been established.
During the whole night, a person realizes 4-6 complete sleep cycles..
The first cycle contains only 10 minutes of deep sleep with quick movements of the eyeballs and complete muscle relaxation. Gradually, from cycle to cycle, the duration of deep sleep phases increases and in total its duration during the night is 1.5-2 hours. Often this phase of sleep is called paradoxSince the brain is in an active state and the body is practically paralyzed, the perception of external stimuli is turned off.
To regulate sleep cyclesas well as maintaining wakefulness, the inner region of the pons and brain stem is considered the most important. In animal experiments, it was found that the activity of the neurons of the reticular formation of the bridge changes before the change of sleep phases. For example, before the onset of the deep sleep phase, the frequency of impulses of these neurons increased 100 times as compared with the state of calm wakefulness.
The neurons of the bridge, which are active during deep sleep, and the neurons of the blue spot and suture, which are inactive during this phase of sleep, are interconnected. This means that the two most important mediator systems of the brain work together to regulate brain states. Other brain systems are also involved in moving it from one state to another. These are dopaminergic (emitting dopamine) and cholinergic (emitting acetylcholine) neurons of the diencephalic brain and pons. All of the above systems are organized by the type of divergent networks with one input and multiple outputs. From the accumulations of such neurons (nuclei), their axons diverge and are directed to many areas of the brain, regulating their activity.
Clinical observations of patients with local lesions of deep brain structures and sleep disorders led to the conclusion that the structures surrounding the sylviae aqueduct and located in the posterior wall of the third ventricle of the brain play a special role. Irritation of these zones by the pathological process causes prolonged sleep in a person due to the spread of inhibition to the thalamus and cerebral cortex. Irritation of the corresponding areas of the brain of animals by impulses of electric current confirmed the presence of " sleep center ".
Wakefulness and sleepBeing two polar functional states of a person, they also reflect various states of his of consciousness.
- Waking implies the possibility of human awareness of mental and (or) physical activity.
- The processes occurring in a dream are not realized.
A third of life is spent by a person in a dream: he sleeps 20 years of life out of 60, respectively 25 of 75 years. Man has risen to immeasurable height above the world of animals, but sleep every day brings him back to a state that occurs in animals and children. This state has long attracted the attention of philosophers, poets, and doctors.
On the one hand, sleep is regarded as happiness. “I am happy who sleeps, who caresses spring in a rainy day”. There is an expression “Sleep hugs”. “Happy is the one whom the dream invariably attends, to whom he appears at a certain time, for a certain period and leaves as quietly and imperceptibly as he came,” - so poetically and beautifully written about the dream. The philosopher Schopenhauer said: "A dream is for man the same as a watch factory." “Sleep is the source of all strength, a balm for a sick soul,” wrote Shakespeare.
On the other hand, sleep was sometimes defined as a state close to death: "tormenting dreams fly over sinful people," "Sleepy, that dead," "Sleep, and die," "Sleep like a dead (dead person's sleep)."
People call sleep sweet, light, heavy, strong, nervous, tender, serene, anxious, transparent, bewitching, deep, dead, black. Each of these definitions reflects a subjective attitude to sleep.
In the past, sleep was divided into imperative and strong-willed. The first comes periodically in accordance with the “imperative need of the organism.” The imperative need is especially manifested during prolonged wakefulness, fatigue. The famous Russian linguist, the creator of the explanatory dictionary V. I. Dahl, a doctor by training, recalled how, being extremely weary, he fell asleep on the battlefield among wounded and killed soldiers. The willful dream arises at will and is a luxury, pleasure, habit, not being necessary, it is pleasant. Such is, for example, morning re-sleep after waking up, when the question is decided whether to sleep further or not, imperative need is no longer here, since the need is satisfied, as a rule, even before the morning awakening.
What is the normal duration of sleep? Is it good to sleep a lot? What factors determine the duration of sleep?
Normal sleep duration
First of all, the age factor plays a role. Based on the observations, it was believed that:
- newborn up to 4-6 weeks awake 2 hours a day
- in 1-2 years - 6-8 hours
- in 2-3 years - 7-9 hours
- in 3-4 years - 8-10 hours
- in 4-6 years old - 9-11 hours
- 6-9 years old - 12-14 hours
- at 9-13 years old - 14-16 hours
In adolescence, usually sleep 8-10 hours, after 20 years - 6-8, at an average age - 5-7. The night sleep of the elderly is somewhat shortened. This is not about the daily duration of sleep, often increased in old age.
These data are clarified recently, especially in relation to sleep in children. These clocks turned out to be sharply exaggerated, since two states were analyzed: rest and activity by behavioral manifestations. Electroencephalographic data showed that during sucking the child may have an EEG sleep model, and at rest the EEG wake model. In this way, it was established that the sleep of a newborn is 16.3 hours (instead of the 22 hours considered). The longest continuous period of sleep lasts 4 hours, and the ratio of the duration of a night's sleep to the duration of a day is expressed by a ratio of 100: 98. Already in the third week of life, night sleep is 14.8 hours. The longest period of uninterrupted sleep reaches 8.48 hours, and the ratio of night sleep to daytime is 100: 46. Children have a very responsible age of 5-6 years old when they first go to my sleep phase, that is, they divide the day into two periods: sleep and wakefulness. The body prepares for this gradually, moving gradually from multiple periods of daytime sleep to a one-time sleep in the daytime, until it completely breaks up with polyphasic sleep.
Change of sleep and wakefulness at different ages
1 - newborn; 2 - 1-2 years; 3 - 4 years; 4 - 10 years; 5 - adult
In adolescence, sleep is indeed somewhat longer than in mature age, when individual characteristics and sleep habits are finally formed. It should be firmly remembered that no average indicators can reflect the numerous options for the normal duration of sleep. In an adult, they range from 4 to 10 hours. These fluctuations have to be considered when assessing the individual characteristics of the established sleep habits.
It should be emphasized that a lot of sleep is harmful. The subjective need for prolonged sleep often does not reflect the true need for it, being only a consequence of a habit, often formed in childhood. Excessive sleep in a child contributes to the development of phlegm, retards mental development, violates the function of blood circulation and digestion.
The German philosopher Immanuel Kant believed that anyone who sees a dream as a pleasure or a means to kill time and gives him more than a third of his life, or even sleeps little by day, does not know how to assess his life, either qualitatively or quantitatively. The same ideas are reflected in Russian proverbs: “Whoever sleeps the most, he lives the least”, “Sleep a lot - live a little: what’s left is lived.” Evmey, the divine swineherd, says to Odyssey: "It is harmful to sleep beyond measure." In the old manuals devoted to sleep, it was stated that the poorer the mental content, the easier it is to part with it, the easier it will be to sleep.
Many people sleep with reduced intelligence and people who are at a low level of development. Maclay noticed that the Papuans sleep a lot and fall asleep in any position. The same can be said about people inactive, inert, such as described Oblomov by Goncharov. “Drowsy and lazy,” proves popular wisdom. It was really noticed that people are energetic, mobile, living a tense inner life, sleeping less than the average norm. First of all, these are scientists and prominent political figures. (We will return to this question in the chapter on sleep and wakefulness disorders.) It is noted that older people who have retained a good intellectual form have a shorter sleep than those who have lost it. It should be noted that from the above regularity there is a large number of deviations. Nevertheless, it is hardly necessary to consider the deviation of the sleep duration towards lengthening useful.
It is necessary to take into account the sleep characteristics of elderly people, characterized by a moderate decrease in the total night sleep time, an increase in the number of waking up, a decrease in the proportion of the most deep stage of slow sleep and a moderate decrease in REM sleep. (The duration of REM sleep in old age is evenly distributed between the first and second halves of the night.)
In addition to age and habits, a number of external factors and environmental conditions can influence the duration of sleep. Hard work, accompanied by a full sense of mental and physical fatigue, contributes to the lengthening of sleep, on the other hand, inactivity leads to the same (for example, during the vacation period).
In the past, people slept more in the village than in the city (mainly in winter). Now electrification, televisions, the Internet and, finally, the growth of the cultural level of the people living in the countryside have practically erased these differences. Working conditions still determined a relatively shorter sleep period in summer during field work compared with the rest of the year.
One of the factors affecting the duration of sleep is also the external temperature. Sleep causes both high and low temperatures. In the most acute form, this is observed in cases of the onset of an invincible long sleep under cooling conditions, during arctic expeditions. In James Aldridge's novel The Son of a Stranger's Land, the onset of sleep in the desert under the influence of heat is described.
All this shows that the influence of environmental factors is also superimposed on the habit developed by a person for a certain duration of sleep.
As already mentioned, from 5-6 years of age, sleep is monophasic. Nevertheless, it is common in most southern countries to sleep during the day for 2-3 hours, as a result of which people get up earlier and later lie down. This custom is caused by the difficulty of working during the hottest period of the day. It is inexpedient to object to this custom, since such a sleep formula has been developed for thousands of years and has an undoubted meaning.
The habit of daytime sleep is widespread in all civilized countries. US President Harry Truman has publicly stated that he outlived all the members of his cabinet, because he never denied himself a day dream. Winston Churchill regularly slept during the day, while he went to bed undressed. So do some famous scientists, figures if they have at their disposal no more than 20-30 minutes. In their opinion, only such a dream brings the necessary rest.
It is very difficult to decide whether it is good to sleep during the day. In ancient times, afternoon nap was not permitted. Eastern wisdom says that naps should not last more than 60 breaths, i.e. more than 4 minutes. Despite such specific statements, it is impossible to resolve the issue unequivocally. Based on a number of considerations, it is impractical to systematically add to the 8 night hours of sleep another 1-2 hours of the day. It should be borne in mind that daytime sleep falls on the clock of the daily rhythm, characterized by maximum efficiency - this is also a lack of daytime sleep. On the other hand, apparently, it is necessary for people who are accustomed to daytime sleep. There are considerations for and against daytime sleep - everyone should decide this question independently, there are no general recommendations here.
- 29.84 KbTuva State University
Faculty of Philology
Sleep and wakefulness.
Completed: student 1 course
3 groups Mongush Aldynmaa
Checked: Kuular A. S
Kyzyl - 2012
Mechanisms of sleep and wakefulness of the body ……………………………… .3
The role of humoral factors and the occurrence of sleep .........................4
The value of sleep ……………………………………………… ………………… ..6
Conclusion …………………………………………………… ……………… 7
References ... ………………………… ……………………………… 8
Mechanisms of sleep and wakefulness
Any activity of the body takes place against the background of a certain activity of brain structures. The background activity of the brain structures on which any activity of the organism is superimposed is called a functional state. This activity depends on a complex of circumstances: the time of day, the preceding activity, the involvement of motivational processes, and so on. Traditionally, researchers have identified two main functional states of the body - sleep and active wakefulness. Initially, it was assumed that these two functional states differ in the level of brain activation, and it was understood that sleep was due to its decrease, and wakefulness - by increasing. But after it was proved that sleep is a special functional state with a specific pattern of the activity of brain structures peculiar only to it, such a separation of these states by the magnitude of the activation level became incorrect.
The state of wakefulness is the result of the body's active adaptation to changing conditions of existence. It depends on a person’s ability to record external and internal signals (perception), on his desires (motivational sphere), on tasks and goals that he defines for himself (cognitive sphere) and on his ability to move (motor sphere). All these processes, proceeding against the background of the state of wakefulness, are themselves actively involved in its change.
Many processes in the body occur rhythmically. The sleep-wake cycle is constantly adjusted to external sensors (length of day and night) and is 24 hours. Synchronously, he tuned other rhythms of the body - hormonal, biochemical, physiological, emotional, behavioral. Under natural conditions, the biological clock is regularly synchronized with the day-night cycle.
Sleep is a physiological condition that is characterized primarily by the loss of the active mental connections of the subject with the world around him. Sleep is characterized primarily by the loss of active consciousness. A deeply dormant person does not respond to many environmental exposures unless they have excessive force. Reflex responses during sleep are reduced. Another indicator of the state of sleep is the loss of ability to actively target activities.
The role of humoral factors and the occurrence of sleep.
Sleep is the physiological need of the body. It takes about 1/3 of a person’s life. During sleep, there are a number of changes in the human physiological systems: there are no consciousness and reactions to many environmental stimuli, motor reflex reactions are sharply reduced, and the body's conditioned reflex activity is completely inhibited. Significant changes in the activity of the vegetative functions were found: the heart rate and blood pressure decreases; breathing becomes more rare and shallow; decreases the intensity of metabolism and slightly decreases body temperature; decreases the activity of the digestive system and kidneys. During deep sleep, a decrease in muscle tone is noted. In a sleeping person, most muscles are completely relaxed.
The scientific study of the physiological mechanisms of sleep began in the middle of the nineteenth century. To date, many different theories have been created, which can be summarized in two main groups.
1. The first group includes the so-called - humoral theories of sleep, linking the occurrence of sleep with the accumulation of certain chemicals in the blood of the body - hypnotoxins.
Chemical theory According to this theory, easily oxidized products accumulate in the cells of the body during wakefulness, as a result there is a shortage of oxygen, and the person falls asleep. According to the psychiatrist E. Klapareda, we fall asleep not from being poisoned or tired, but in order not to get poisoned or tired.
However, in recent years, the work of P. K. Anokhin and employees has proved that humoral factors play a secondary role. In particular, in the observations of the accreted so-called Siamese twins, who had only general circulation, it was found that they had a non-simultaneous sleep. One twin can sleep, and the other - be awake. If the main cause of sleep was the accumulation of hypnogenic substances in the blood, i.e. substances that cause sleep, then both Siamese twins would sleep simultaneously.
Chemical theory cannot also answer a series of questions. For example, why does daily food poisoning do no harm to the body? What happens to these substances for insomnia?
2. As a result of objective criticism, humoral theories of sleep have receded into the background, and theories explaining the emergence of sleep by changes in the activity of the nervous system are currently becoming more popular.
Among these neurogenic theories, the cortical theory of IP Pavlov was of particular importance. The study of the processes of inhibition in CHM allowed him to suggest that sleep is also a kind of inhibitory process, spreading "completely to the whole mass of the hemispheres and to the underlying brain regions."
Value of sleep
Sleep contributes to the processing and memorization of information. In a dream, mobilization of memory mechanisms is facilitated, since the external information load caused by noise interference and other factors is reduced. During fast (paradoxical) sleep, secondary information is excluded from memory. Fast sleep and dreams are necessary to adapt to informationally meaningful information. The fast phase of sleep also contributes to the improvement of mnestic processes. In addition, it is shown that sleep (when the mind does not control the intellect) is a necessary condition for the inclusion of intuition. During sleep, poets, composers, scientists can activate creative processes, the results of which are reflected in dreams. It should be emphasized that the stimuli acting in a dream are peculiarly reflected in the content of dreams. The stronger and more significant for a person is an internal or external stimulus, the less expressive or less emotional the content of the dream will be, and vice versa. Weak stimuli, such as long-forgotten impressions, neutral remnants of impressions, weak external stimuli during sleep, are presented in dreams with very impressive pictures, and strong impressions of the previous day or strong external stimuli are often not represented at all in dreams.
During sleep, there is a compensation arising during the period of wakefulness of disagreements of cognitive, mnestic, emotional and other mental processes. The authors believe that the segments of sleep stages are important elements that reflect the functionality of sleep and the brain as a whole. The internal organization of sleep is determined by the fact that the brain needs to recreate the lost, debug existing ones and create various options in the system of interneuronal interaction, modified during the period of previous wakefulness. The purpose of sleep as a debugging mechanism, in which the coordination of the interneuronal and intersystem interactions is worked out, is aimed at restoring order in the brain activity. Transforming sleep into relative chaos in real life conditions, especially stress and insomnia, can be a cause of disturbed sleep patterns.
Conclusion
Sleep is a physiological condition characterized by the loss of the active mental connections of the subject with the world around him. Sleep is vital for higher animals and humans. For a long time it was believed that sleep is a rest necessary for the restoration of the energy of brain cells after active wakefulness. However, it turned out that brain activity during sleep is often higher than during wakefulness. It was found that the activity of neurons in a number of brain structures during sleep significantly increases, that is, sleep is an active physiological process.
In the twentieth century, our knowledge of the world of sleep expanded enormously. The recognition and analysis by Freud of dream values, the discovery of the connection between rapid eye movements and dreams made by Azeri and Kleitman, the ongoing work on the study of brain chemistry, hormonal activity during sleep — all these important discoveries bring us closer to a deeper understanding of the physiological and psychological mechanisms of sleep.
The value of sleep .................................6
Conclusion ………………………………………………………………………… 7
References ... ………………………………………………………… 8
Sleep rhythm due to many reasons. Some birds and animals, for example, sleep during the day and hunt at night. People who fall into the dungeon, because of the need to have to change the "habits". It is easier for the younger ones. Working in night shifts in most cases are also rebuilt according to the “new schedule”. And in general, after the appearance of electricity, the general for all regime undergoes certain changes: the day is prolonged due to artificial lighting and the night is reduced, which means that the wakefulness period increases.
A man sleeps about a third of his life. If you sleep on average not 8, but only 2 hours a day, then by the age of 70 another 17 years will be added. How many interesting and valuable ideas can be accomplished during this time! However, this is a matter of the future. The secrets of sleep are just beginning to await. If today, with an effort of will, someone forces himself to gain time for work at the expense of a night's rest, then in the end he still loses - tired “mechanisms” reduce their performance, or even undergo painful violations.
The causes of fatigue and sleep to this day are completely unknown. Some researchers believe that fatigue occurs when the reserves of enzymes and catalysts are exhausted, especially in the neuro-cellular systems, which leads to a gradual extinction of their activity. Replenished the same stocks can only be due to the development of the brake state, mainly during sleep. Other scientists attribute the leading role to accumulation in various tissues, especially in muscles, of decay products, which poison them and require “stopping” for their elimination; They also press on a brake pedal of wakefulness.
If these reasons remain so far under question, then thanks to modern scientific advances one can speak more clearly about the physiological mechanisms of sleep. Sleep - not frozen, motionless state, simultaneously replacing wakefulness. It depends on the depth and extent of inhibition. Just as the degree of wakefulness varies, so does the quality of sleep. Between wakefulness and sleep, there exists, as it were, an intermediate state of relative equilibrium between physiological arousal and inhibition. This state has received the name prosonochnogo.
When falling asleep, first of all, cells and parts of the cerebral cortex responsible for the second signaling system are subjected to inhibition. They are less stable compared to evolutionally older brain regions responsible for the first signaling system. Separate areas of the cortex and subcortical formations of a falling asleep person have, for some time, continued their “reflective” activity, but without correction of the higher brain regions. As a result of this, “semi-rial”, vague, plastic images appear that are devoid of, as a rule, spatial orientation.
The physiological processes of inhibition never capture the entire cortex. Certain "siders" constantly, even with seemingly deep-seated sleep, continue to associate a person with the surrounding world. They change with different people and under different conditions. A tired mother can sleep among the diverse noises, but the child should cry as she is there.
In animals, sleep is also not completely complete. Watch the sleeping cat. Her ears often move, and you should hear the rustle, reminiscent of the rustle of the mouse, as she immediately jumps up.
Very interesting are observations of huge molluscs with large heads and eight tentacles-legs living in Italy at the marine biological station. Dropping to the bottom of the aquarium and going to bed, the clam envelops its head with seven tentacles, and the eighth “leg” lifts up. It resembles a guard guarding a sleeping unit. The wrapped up head can be touched and pushed - the clam does not move. If you touch the eighth tentacle, it immediately awakens and sails to the side. The brain guard station is a necessary protective device for all living things.
During deep sleep, not only does consciousness “stop functioning”, but a complex of changes occurs in the internal organs of a person. The activity of most of them begins to take place at the "minimum level". In the waking state, the necessary substances are consumed; in a dream, on the contrary, they are assimilated. Blood pressure decreases, the temperature of the body drops slightly, but the digestive organs, liver, pancreas remain in their regime. The beginning of the decrease in muscle activity is well known to each of us, it is like the first sign of a moving sleep - lethargy appears, the eyelids, arms and legs become “heavy”. With deep sleep, the muscles are completely relaxed. That is why the sleeping man’s arm hanging from the roof reminds of a limply whipping whip.
The need for sleep is different. As a rule, the older a person is, the less time he sleeps. Newborn babies need to sleep 22 hours a day, an old man - no more than 4-5. This is primarily due to the fact that a growing, actively consuming body energy reserves (first of all, this applies to children) need a longer rest to replenish lost energy.
Without sleep, the life of people can last much less than without water and food - no more than 10 days. In the Middle Ages and in the fascist dungeons during the Great Patriotic War, sleep deprivation was used as a particularly sophisticated torture.
Of course, speaking of a dream, it is impossible to say nothing about dreams. In the figurative expression of I. M. Secheno-va, dreams are “an unprecedented combination of past impressions”. In them, in a special form, the nerve tracks of the experiences that took place take place, that is, the mechanisms of memory and perception manifest themselves in a peculiar way. The “special conditions” depend on more or less inhibition. Chaotic thinking, lack of coordination of consciousness, is the most common characteristic of dreams.
The successes of science in recent years with great certainty allow us to establish how a person sleeps. When someone is said to be sleeping like a dead person, this is not true. Any person in a dream makes at least 20 to 60 minor movements, spending 30 seconds out of each hour. In the second half of the night, people move more than in the first. Children - more often than adults.
We can assume that people who do not know dreams, no. Every normal person has four or five dreams at night, but does not always remember them. The American physiologist N. Kleitman, who had devoted more than forty years to the description and study of sleep, drew attention to the fact that during the night the sleeping eye periodically repeats rapid eye movements. Yes, it was possible to register this movement. Electroencephalogram-we showed that the appearance among the slow "sleepy" waves of the increased electrical activity of the brain, previously treated simply as a superficial sleep, coincided in time with the movement of the eyes. This led Kleitman and his staff to the idea that the enhancement of electroencephalographic activity and eye movements could be due to one reason - the vision of dreams. To confirm this assumption, many researchers in different countries made careful observations. Immediately after registering a series of eye movements, sleeping subjects were woken up and asked if they had seen
The objective method of studying dreams allowed to reveal a number of patterns in their occurrence. It turned out that dreams begin only after a certain period of deep sleep, when a steady “sleepy” rhythm is recorded on the electroencephalogram. Then they appear almost regularly with an interval of about one and a half hours. The first dream does not last long, the next gradually increase, and the latter may take more than an hour.
There are often cases when a person “in a dream” decides what he could not decide during the day, remembers what he could not remember the day before, even creates what he did not succeed before. For example, A. S. Pushkin “composed” some poems in a dream and, on waking, immediately wrote them down. In A. S. Griboyedov's plan “Woe from Wit” also matured during the night's sleep. The well-known chemist Kekule in his dream for the first time made up the formula of benzene. I. S. Turgenev, L. N. Tol-stoya, A. P. Chekhov wrote about creative “insights” in a dream. Such “whims” of creativity, which idealists cling to tenaciously, proving the influence of both the unconscious and the supernatural (most often divine) on the conscious human activity, are quite understandable. Any question that “clears up” before us in a dream, the day before, sometimes not only on this day, but also for many weeks or months, occupied and stirred the brain. The decision ripened gradually, but it could not take final shape, something interfered with, including insufficient concentration of attention due to various matters that had to be performed. During sleep, a person is relieved of irritants, many areas of the cortex are slowed down, and the most agitated ideas on the subject of interest and tormenting matter “leave to rest”. They leave, but they have not left yet. And here, in a half-awkward state, sometimes the best conditions are created for solving the problem. Both Pushkin, and Griboedov, and Kekule relentlessly, with inspiration, thought, nursed their ideas and fell asleep, of course, with thoughts about them, until one day a clear decision was born in the muffled sleep. Without the intense preparatory creative work, happy creative dreams would never have been possible.
The dream environment is greatly influenced by the environment. A perfume with a strong smell broken in a room often causes sleep with the sensation of cologne. The occasional noises of the street, penetrating through a window, the measured snoring of a neighbor, the sound of a ticking clock — all this can serve as an incentive for “sleepy symphonies”, winds and shouts. Once the faces of a large group of subjects were sprayed with water. When they woke up, they told me that they dreamed about one thing, how they were playing, others saw themselves in the shower. Such dependence of the plot of dreams on the situation once again confirms that wakefulness and sleep are only two interconnected sides of one physiological process.
Dreams of people have long been trying to interpret and see in them the prophetic predictions. In pre-revolutionary Russia, and even now in some countries, “guides” - “dream books” are published. But the interpretation of dreams ultimately depends on their content, and the content can be nothing more than a product of processing signals from the brain external and internal (located in different parts of the body) stimuli and from the pantry memory. So, it’s at least absurd to look for indications of the future in “sleepy thoughts”.
Useful or harmful dreams? This question can be answered differently - they are necessary. Scientists have been doing the following experience. As soon as the examined persons in a dream began to move their eyes, they were woken up; the control group was awakened only after the completion of the "sleepy" cycles. An interrupted pattern was observed in people with interrupted dreams — breaks were becoming more frequent. One of the subjects on the eighth night of the experiment recorded about 200 cycles of dreams. In the control group, nothing like this happened. However, this is not all. People who were deprived of dreams, after a few days, became irritating, nervous, their appetite changed. Obviously, for normal life the body needs a certain number of dreams.
Kamenkov M. Yu.
Sleep physiology
Human behavior during sleep
A waking person interacts with the environment, responding to external stimuli with adequate responses, and during sleep this connection is interrupted by the outside world, but does not disappear completely. A sleeping person may wake up under the influence of external stimuli, the most important ones that carry biological significance. However, loud noise, which does not matter much, does not cause the sleeper to wake up, although it disrupts the phase sequence and, as a result, negatively affects sleep. During sleep, the brain does not work at some constant level. The degree of attention of a sleeping person varies; in this regard, sleep is divided into several stages; indicators of each stage is the depth of sleep, measured as the threshold force required for awakening.
The following stages of sleep are distinguished:
1. Relaxed wakefulness (alpha rhythms with variable amplitude prevail on the EEG) (Fig. 1).
2. Stage A sleep: the alpha rhythm gradually disappears. Small theta waves appear at long intervals.
3. Stage B sleep: this is the stage of falling asleep; characteristic are theta waves, high amplitude vertex teeth, of 3-5 s duration. Man does not distinguish weak external stimuli.
4. Stage C sleep: superficial sleep. Characterized by fusiform bursts of the beta rhythm and K-complexes.
5. Stage D sleep: moderately deep sleep. Delta waves with a frequency of 3–3.5 Hz are recorded.
6. Stage E sleep: deep sleep. Characteristic delta waves with a frequency of 0.7 - 1.2 Hz.
7. Before awakening, a person goes through another stage of sleep (BDG sleep), characterized by EEG desynchronization and episodes of rapid eye movements (Fig. 2). In addition, finger twitching is observed.
Over the course of all nights, the sequence of stages is repeated about 5 times. The depth of sleep decreases with morning.
With age, the ratio between wakefulness and sleep, and also between the last phase of sleep and the remaining 6 stages of sleep changes: there is a gradual decrease in the duration of sleep, shortening the last stage of sleep.
A significant proportion of BDG-sleep in newborns is higher than that of anyone. This dream plays an important role in the ontogenetic development of the central nervous system: infants receive less information from the environment than adults, and their sleep provide internal stimulation that compensates for the lack of external stimulation.
There is another classification of sleep stages:
1. Equalization phase: is characterized by the effect on both strong and weak stimuli.
2. Paradoxical phase: strong stimuli cause weaker responses than weak stimuli.
3. Ultradoxical phase: a positive stimulus inhibits, and a negative stimulus causes a conditioned reflex.
4. Drug phase: a general decrease in conditioned reflex activity with a significantly stronger decrease in reflexes to weak stimuli than to strong ones.
5. Braking phase: complete inhibition of conditioned reflexes
Sleep and dreams
It is easier to remember a dream if you wake up a person during the BDG phase of sleep or after it ends. A person who wakes up during a slow sleep does not remember dreams, therefore dreams arise during fast sleep; during the latter, there is a dreaming, talking, night fears in people.
Previous events have an effect on dream content: when thirsty, BDG sleep and dreams become more pronounced. If a person is awakened during the BDG phase, then the subsequent stages become longer, dreams are brighter, the body is catching up, as it were, and no pathological changes occur. External stimuli (especially auditory) fit into the dream picture; the connection of these stimuli with the dream content is evidence that during the slow sleep phase they are more real and resemble more stimuli.
Memory during sleep worsens: a person remembers the last dreams. But sleep facilitates the consolidation of the material being studied. Material memorized before bed is remembered better than the same material learned in the morning or afternoon that bind
1. First: during the daytime there are many stimuli that interfere with the process of memorization, in the interval between their memorization and reproduction.
2. Secondly: forgetting can be a violent process that is slower in a dream.
Mechanisms of wakefulness and sleep
Diafferential theory of sleep and wakefulness
In the late 1930s, Bremer discovered that an EEG of a cat with a transect separating the spinal cord from the brain after recovering from an operating shock exhibits cyclical alternations characteristic of sleep-wakefulness.
If the transection was performed at the level of quadrilateral, that is, sensory stimuli were excluded, except for visual and olfactory, an EEG typical for sleep is observed.
Bremer concluded that the central nervous system is induced and maintained: wakefulness requires a minimum of sensory stimulation, sleep is a condition characterized primarily by a decrease in the efficiency of sensory stimulation of the brain, which confirms the theory of passive wakefulness.
But:
first: in an isolated forebrain, rhythmic oscillations characteristic of the sleep-wake rhythm appear over time. In addition, the isolation of a person in a soundproof chamber leads to a decrease in the duration of sleep.
Secondly: the data on the effect of the cortex on the state of wakefulness are incorrect, since the circadian rhythms of sleep-wakefulness are also observed in newborn children of aencephalics.
Reticular theory of sleep and wakefulness
In the reticular formation of the brainstem there is a multitude of neurons, whose axons go to almost all areas of the brain (except the neocortex). In the late 1940s, Moruzzi and Megun discovered that high-frequency stimulation of the reticular formation of the brain stem of cats leads to their instantaneous awakening. Damage to the reticular formation causes a constant sleep, but perezzka same sensory tracts of this effect does not.
The reticular formation began to be considered as an area of \u200b\u200bthe brain involved in maintaining sleep. Sleep occurs when its activity is passive or under the influence of external factors falls. Activation of the reticular formation depends on the number of sensory impulses entering it, as well as on the activity of the descending fibers between the forebrain and stem structures.
However, it was later found that:
1. First: the reticular formation causes not only wakefulness, but also sleep, which depends on the place of application of the electrodes when stimulated by electrical stimulation.
2. Secondly: the neural state of the reticular formation in the waking state and during sleep is not much different.
3. Thirdly: the reticular formation is not the only center of wakefulness: they are also represented in the medial thalamus and in the anterior hypothalamus.
Cortical-subcortical theory
There is a reciprocal relationship between the limbic-hypothalamic and reticular structures of the brain. When the limbic-hypothalamic brain structures are excited, inhibition of the structures of the brainstem reticular formation is observed and vice versa. In wakefulness, due to the afferentation flows from the sense organs, the structures of the reticular formation are activated, which have an upward activating effect on the cerebral cortex. At the same time, the neuron of the frontal cortex has descending inhibitory effects on the sleep centers of the posterior hypothalamus, which eliminates the blocking effects of the hypothalamic sleep centers on the reticular formation of the midbrain. When the flow of sensory information decreases, the ascending activating effects of the reticular formation on the cerebral cortex decrease. As a result, the inhibitory effects of the frontal cortex on the neuron of the center of sleep of the posterior hypothalamus, which begin to inhibit the reticular formation of the brain stem, are eliminated. In the conditions of blockade of all ascending activating effects of subcortical formations on the cerebral cortex, a slow-wave sleep stage is observed.
Hypothalamic centers due to connections with the limbic structures of the brain can have ascending activating effects on the cerebral cortex in the absence of the influence of the reticular formation of the brainstem. These mechanisms constitute the cortical-subcortical theory of sleep (PK Anohin), which made it possible to explain all types of sleep and its disorders. It proceeds from the fact that the state of sleep is associated with the most important mechanism - the decrease of the ascending activating effects of the reticular formation on the cerebral cortex. Sleep of barkless animals and newborns is explained by the weak severity of the descending effects of the frontal cortex on the hypothalamic sleep centers, which under these conditions are in an active state and have a inhibitory effect on the neuron of the reticular formation of the brain stem.
Serotonergic theory of sleep and wakefulness
In the upper sections of the brain stem, two areas were found: the core of the suture and the blue spot. The mediator in the cells of the nucleus of the tent is serotonin, and the blue of the place is norepinephrine.
In the late 1960s, Jouve came to the conclusion that these two neural systems take part in the occurrence of sleep. The destruction of the seam nuclei in a cat leads to complete insomnia within a few days, in the next few weeks sleep is restored. Partial insomnia can be caused by the suppression of the synthesis of serotonin by chlorophenylalanine, the introduction of a precursor of serotonin can be eliminated. The destruction of the blue spot leads to the complete disappearance of BDG sleep, but does not affect slow sleep. Depletion of serotonin causes insomnia, and the introduction of serotonin precursors normalizes only slow sleep.
All this suggests that serotonin leads to inhibition of the structures responsible for wakefulness.
It was found that the blue spot suppresses the impulse of the weld core, and this leads to awakening.
It has now been proven that neuron of the suture nuclei secrete serotonin during wakefulness: it serves as a mediator in the process of awakening and the “sleep hormone” in the waking state: stimulating the release of the sleep substance that causes sleep. The phase of BDG sleep is provided by a hollow core.
It has been shown that sleep and wakefulness are determined by the activation of specific brain centers.. One of these centers is the reticular formation, which is located in the brainstem. It is one of the main components of the reticular formation that are cholinergic nuclei located at the level of the bridge-mid-cerebral articulation. The neurons of these nuclei have a high level of activity during wakefulness and REM phases and are inactivated during slow sleep.
Other ergic systems of the brain, mediators of which are: serotonin, norepinephrine, histamine, glutamate, vasopressin, take part in the regulation of sleep-wakefulness processes. It is likely that dissomnias are caused by the disruption of the functioning of neurotransmittern systems.
Endogenous sleep factors
A person feels a certain need for sleep, which is associated with the presence of sleep factors circulating in the blood. Then during sleep their normal concentrations should be restored. It is assumed that sleep factors accumulate during wakefulness to a sleep-inducing level. According to another hypothesis, these factors accumulate during sleep: they form and stand out.
A glycopeptide, a delta peptide, was isolated from urine and spinal fluid, causing slow sleep when administered to other animals. There is a factor and REM sleep.
The second hypothesis has led to the discovery in the blood of a delta-sleep peptide that causes deep sleep.
However, the factors found cause sleep in humans and only in some animal species. In addition, it can occur under the action of other types of substances. To date, it is not known what physiological role the found factors perform in the process.
Sleep Functionality
With long-term total sleep deprivation of up to 116 hours, there are disorders of sleep, behavior, mental processes, the affective sphere, and the appearance of hallucinations (especially visual). Slow sleep prevails on the first recovery night, whereas the disappearance of paradoxical sleep (PS) was observed, but later a PS prolonged and an increase in BDG sleep occurred.
With deprivation and PS, behavioral disturbances occur, fears and hallucinations appear, however, the effect with deprivation and PS was less significant than with deprivation and slow sleep. In subjects who had dreams on a recovery night, no compensatory increase in PS was observed. In subjects who have observed behavioral disorders, hallucinations, etc. an increase in PS was observed.
It was established that during the deprivation and sleep the concentration of delta peptide increases, its introduction into the thalamus zone caused an increase in slow sleep and PS. The sleep factor, which is used in immunological protection, also accumulates.
According to J. Oswald, slow sleep is needed to restore the performance of brain cells. During sleep, he is released from the hypothalamus growth hormone, he is involved in protein biosynthesis in peripheral tissues. The biosynthesis of proteins and RNA neurons is intensified during PS. According to Laborie, slow sleep is associated with the metabolic activity of the neuroglia.
J. Moruzzi distinguishes two types of regenerative processes in nervous tissue.
1. Fast processes: in neuron ah, performing the function of conducting and synaptic transmission of impulses, these processes last for a few seconds, which can occur during wakefulness, without interrupting the activity of the neuron itself - sleep is not needed for this.
2. Slow processes are necessary for neuron am, whose synapses are subject to plastic changes during learning. The perception of all kinds of conscious life that are associated with higher functions. Sleep is not a recovery period for the entire brain, but only a recovery period for synapses with plastic properties. In contrast to the "fast", these processes are covered by positive feedback, due to which they support their activity, not falling down "quickly."
PS is associated with motivational functions: during dreaming, the satisfaction of those needs that were not achieved while awake occurs. During sleep, the release of motivational energy occurs and, thereby, the state of the body is maintained. In patients with endogenous depression, which are characterized by abnormal vivid dreams, motivational processes in a dream are strongly represented, which leads to a decrease in the severity of these processes during wakefulness. On the other hand, deprivation of BDG sleep leads to the severity of motivational processes during wakefulness, which reduces the severity of endogenous depression (Vogel). What is the basis of the effect of antidepressants
Changes in the concentration of hormones during sleep
|
Hormone |
Sleep phase |
Sleep phase |
|
Stg |
Decrease in concentration |
Increasing concentration |
|
With deprivation and sleep in the second half of the night, the level of GH in the blood, compared to normal, increases. On the same night, when the deprivation was made, its level did not change. |
||
|
Prolactin |
Decrease in concentration |
Increasing concentration |
|
FSH and LH 1. In adults: |
Decrease in concentration |
|
|
2. Pubertal period: |
Decrease in concentration |
Increasing concentration |
|
TSH |
Decrease in concentration |
Decrease in concentration |
|
ACTH |
Decrease in concentration |
Decrease in concentration |
|
Cortisol |
Decrease in concentration |
Decrease in concentration |
|
Catecholamines |
Decrease in concentration |
Decrease in concentration |
|
With deprivation and increasing their concentration during sleep. |
||
|
Beta endorphins, substance P, cAMP, cGMP |
Constant concentration |
Constant concentration |
|
Parathyroid hormone |
Increase in concentration |
Increase in concentration |
Sleep and wakefulness. Pathological changes.
In 1958-1960 a pattern was found between the duration of sleep and mortality. Basically, both short-sleeping (4-5 hours per day) and long-sleeping (10-12 hours) from cancer, coronary artery disease, often suicides die. Thus, sleep has a restorative effect on both physical and mental health.
Insomnia. Narcolepsy. Hypersomnia.
Insomnia and narcolepsy are hereditary diseases.
Narcolepsy - a violation of wakefulness, characterized by daytime attacks of irresistible sleep. They connect him with the fact that a person suffering from narcolepsy from the state of wakefulness immediately falls into a paradoxical dream. Symptom - uncontrollable sleep, muscle weakness. For many people, the circadian rhythm of sleep - wakefulness is broken. Muscle weakness occurs with anger, laughter, crying and other factors. Hypersomnia is an extraordinary need for sleep, caused by an imbalance of the sleep-wakefulness regulation systems in the body.
We see in dreams various combinations of what happened to us during wakefulness: in the cerebral cortex during superficial sleep or during the transition of sleep from one stage to another, during sleep, the islets remain unbraked parts of the cortex, and under the influence of internal or external stimuli any information, events that have happened to us in reality is “extracted” from them, which is the basis for the emergence of an unreal reality.
During sleep, in our dreams, we see ourselves sick, and in a few days we actually get sick; The fact is that in a dream we become more sensitive, we feel more acutely the processes that occur in our body that we feel in reality.
Snore.
In a dream, the soft tissues of the back wall relax and sometimes block the airways (sticking of the tongue - causes apnea - leads to death) Snoring is a sound generated by the vibrations of the soft tissue, especially the soft palate.
Operations are suggested:
1. Laser surgery, during which excess tissue is burned
2. A new operation during which electrodes are introduced into the soft sky, it heats the tissues with high-frequency electric current, causes them to shrink and returns elasticity in a few weeks.
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