Deep sleep is a complete night's rest. A person’s performance, emotional and physical state. The norm for deep sleep for an adult is from ninety to one hundred and twenty minutes, taking into account several nightly cycles. Duration healthy sleep person is eight to nine hours a day. It consists of four full periods: nap, shallow, slow and deep sleep. Napping is characterized as a superficial state lasting five minutes. At this stage, the body temperature becomes lower, the pulse and metabolism slow down, and breathing becomes quiet. When falling asleep, consciousness turns off, but the reaction to external stimuli remains.

Deep sleep mode helps the body cope with stress and ailments. It helps strengthen the immune system. Dive into deep dream lasts for an hour, after which the rapid phase begins.

Full night cycle healthy person consists of a slow and a fast phase, and takes only about one hundred and twenty minutes. Approximately four cycles occur during the night, the duration of which depends on individual characteristics. The first cycle begins with deep sleep. It lasts a long time, but gradually its duration decreases.

How long should deep sleep last for an adult? Normal cycle is considered to be one that consists of a slow and fast phase, taking into account individual biorhythms. The slow phase consists of the states of drowsiness, falling asleep, deep and delta sleep. During the longest cycle, the human body completely relaxes, functions fade, and weak impulses pass through the brain. It is during this period that the body restores strength and recharges itself with energy.

What are the stages of the slow phase? What makes them special?

1. Nap. A person begins to fall asleep, but the brain continues to be active and creates dreams intertwined with reality. The peculiarity is that it is in the state of drowsiness that the answers to seemingly insoluble problems are found.
2. Falling asleep. Ongoing slow phase. Consciousness gradually turns off, but the brain continues to respond. At this stage, a person can easily be awakened by even a small noise.
3. Deep. Changes begin in the body, all processes and functions slow down, and the body completely relaxes.
4. Delta. It is difficult to wake up a person, since the body is completely relaxed, its temperature drops, and the breathing rate and blood circulation slow down.

How long does slow-wave sleep last? This stage is the longest and depends on the characteristics of the body. Physical endurance and mental activity depend on its quality. If a person does not get enough sleep, he will feel exhausted. Insomnia completely exhausts the body, leading to illness. How many hours does an adult sleep in total? You need to sleep at least eight hours a day. The duration of sleep depends on many factors: age, health, working conditions, biorhythms.

How to increase your night's rest? This is an integral part of human life. In a healthy person it lasts eight hours, but it all depends on biorhythms. For example, older people need less time to sleep, and a growing body needs twice as much time as an adult. Some people need nine hours for proper rest, while others need six. Everything is individual. The main thing is to feel cheerful during the day and be in in a great mood.

NREM sleep consists of four phases: nap, sleep, deep and delta. The peculiarity is that it is very difficult to wake up a sleeping person in the last two cycles.

It is at this time that dreams occur, including nightmares. Normal condition- this is when the four stages of one cycle occupy eighty percent of all sleep.

Deep and slow sleep have their own characteristics:

• in the slow phase, the body physically recovers, strength is restored, tissues and cells are regenerated;
• people who sleep seven to eight hours a day recover intellectual resources faster, and their daytime activities are much more effective;
• An increase in sleep duration helps to strengthen the immune system, and a decrease in sleep duration helps to reduce the body’s protective functions;
• if the slow phase lasts a small number of hours, the aging of the body noticeably accelerates;
• if the deep phase did not last long, signs such as memory deterioration, inability to concentrate on the subject of conversation or problem, and decreased performance appear;
• the slow phase, unlike the fast one, does not have compensatory properties; it is impossible to “get enough sleep” the next night.

Thus, human health depends on the number of hours of the slow phase. If you want to improve your night's rest, you just need to train your body to fall asleep at approximately the same time. The deep phase occupies 12 to 15% of the cycle and is characterized by rhythmic, calm breathing and complete relaxation of the body. The cycle ends with the dreaming stage, during which the pulse and breathing increase.

How long does it take to get a good night's sleep? In this matter, everything is individual. Some people need only five hours for normal healthy rest, while others need ten to get enough sleep. On average, for most people, the overnight recovery period lasts between seven and eight hours. What's happened REM sleep? This period ranges from ten to twenty percent, the remaining eighty is occupied by the slow phase.

The more hours a person sleeps during the delta phase, the better he will feel during the day. A properly structured rest regime and its observance increases the duration of the deep cycle. In order to double your deep sleep time, somnologists recommend following some tips.

1. The normal state of the body is guaranteed by a well-structured regime of falling asleep and waking up. If you independently adjust the duration of rest at night, waking up in the morning will be much easier.
2. Somnologists do not recommend eating heavy food before going to bed. Smoking, energy drinks, caffeine - all of this negatively affects sleep. A good snack would be a glass of kefir or milk, as well as an apple or any other fruit.
3. The deep phase will last longer if you give the body adequate physical activity about four hours before rest.
4. Walking on fresh air, active lifestyle, intense physical exercise during the day they contribute falling asleep quickly and strong good sleep. Light music and aromatherapy will improve your relaxation. Experts say that the quality of deep sleep is positively influenced by the singing of crickets.
5. Before going to bed, it is important to ventilate the room well. Extraneous odors, bright light, and noise do not contribute to falling asleep and the duration of rest.

If you follow these recommendations, you can forget what insomnia is and significantly increase the length of the slow phase. Its peculiarity is that it is during this period that a person restores his physical capabilities. The fast phase helps to improve the functioning of mental processes. Healthy, well-functioning sleep improves immunity, normalizes blood pressure, reduces the risk of heart and vascular diseases, and also mental disorders.

Characteristics of deep sleep

During the night's rest, slow-wave and fast-wave periods alternate with each other. The cycle consists of one period of slow and fast sleep. In total, four to six cycles change each night, lasting an hour and a half. For a child and an adult, the norm is that the deep period is thirty percent.

If a sleeper is abruptly awakened during the deep sleep phase, he will feel tired and exhausted during the day. People with hypertension may experience surges in blood pressure.

The peculiarity is that if a person sleeps well, he will wake up on his own in the morning even from a little noise, and getting up in the morning will be easy. During deep sleep, contact with reality is lost, the body completely relaxes, which gives it the opportunity to recover.

During such a rest, some changes occur in the body:

• muscles completely relax, metabolism slows down;
• At night, the parasympathetic part of the central nervous system is most active, so the pulse becomes slower, blood pressure drops, and the brain practically does not react to external stimuli;
• the gastrointestinal tract slows down its activity, so sometimes upon waking up you may feel slight nausea;
• the cells of the body are restored at night, as growth hormone is actively produced;
• the body expends much less energy than during the day;
• immunity is strengthened;
• If you sleep longer than usual, your physical capabilities increase.

REM sleep is the exact opposite of deep sleep. The body consumes a large number of oxygen, glucose, breathing quickens, pulse increases. Women and men sometimes feel aroused and an erection occurs. Doctors advise sleeping at least seven hours a day. For children, pregnant women and sick people various diseases this norm is higher.

How dangerous is lack of adequate sleep? Almost every person has experienced insomnia at least once. When you try to sleep but can’t, it causes irritation and the body loses more strength than during the day. Isolated cases of insomnia do not harm health; if it becomes systematic, problems arise. In this case, natural sleeping pills or sleeping pills are prescribed, depending on the duration of insomnia.

Sleep disorders are a broad concept that includes problems falling asleep, changes in how you rest at night, and feeling unwell after waking up. All of them are temporary, reversible disorders, but they manifest themselves in the same way. A person feels fatigue, lethargy, apathy, decreased mood, and lacks motivation to work.

The main causes of the disorder are problems of a psycho-emotional nature and somatic diseases.

1. Long-term insomnia is provoked by chronic stress, overexertion, and traumatic factors. Sometimes it becomes cause and effect depressive state, as well as other mental disorders.
2. Diseases of the heart, blood vessels, central nervous system, and malignant neoplasms play an important role in deep sleep disorders. Painful sensations intrusive thoughts illnesses, injuries, osteochondrosis, frequent urge to urinate become grounds for insomnia.
3. Heavy physical activity, unfinished business and questions.
4. Poisoning, problems with the gastrointestinal tract.
5. High body temperature.

If sleep is disturbed, there must be some changes in emotional sphere person. It has been proven that people with psychological problems, high levels of anxiety and depression have the most difficulty falling asleep.

Treatment for insomnia is prescribed after the cause of the condition has been found. To prevent such disorders, it is recommended to walk in the fresh air more often and include vegetables and fruits in the diet. Folk remedies, aromatherapy - all this helps in the fight against the disease.

Rapid eye movement (REM) sleep is a unique phase of mammalian sleep characterized by random eye movements, low muscle tone throughout the body, and the sleeper's ability to dream. This phase is also known as paradoxical sleep (PS) and in some cases as desynchronized sleep due to its physiological similarities to the waking state, including fast, low-voltage and desynchronized brain waves. The electrical and chemical activity that regulates this phase originates from the brainstem and is characterized by a more marked excess of the neurotransmitter acetylcholine in combination with virtually complete absence monoamine neurotransmitters histamine, serotonin and norepinephrine. REM sleep is physiologically different from other stages of sleep, which are collectively called deep sleep (NREMS, synchronized sleep). REM and deep sleep alternate during one sleep cycle, which lasts about 90 minutes in adults. As sleep cycles resume, they shift toward a higher proportion of REM sleep. The transition to REM sleep is associated with noticeable physical changes, starting with electrical impulses called pontogeniculooccipital waves that originate from the brain stem. In organisms in REM sleep, central homeostasis is suspended, allowing large fluctuations in respiration, thermoregulation, and circulation that are not observed in all other phases of sleep or awakening. The body suddenly loses muscle tone, entering a state known as REM sleep atonia. Rapid eye movements and their connection to dreams were identified by Nathaniel Kleitman and his student Eugene Azerinsky in 1953 and later described by researchers including William Dement and Michel Jouvet. Many experiments involved waking up subjects when they began to fall into REM sleep, thus experiencing a condition known as REM sleep deprivation. Subjects were allowed to sleep as usual, allowing for minor REM sleep recovery. Neurosurgery techniques, injections chemical substances, electroencephalography, positron emission tomography, and, of course, reports from sleepers upon awakening have been used to study this phase of sleep.

Physiology

Electrical activity of the brain

REM sleep is called "paradoxical" sleep due to its similarity to awakening. Although the body is paralyzed, the brain functions somewhat as it does in the waking state. Electroencephalography during REM sleep typically shows fast, desynchronized, low-amplitude “brain waves” (neural oscillations) that are distinct from the slow δ (delta) waves of deep sleep, but have similarities to patterns observed during wakefulness. An important component of these waves is the θ (feta) rhythm in the hippocampus. The cortex exhibits 40–60 Hz gamma waves, as during awakening. Cortical and thalamic neurons in the brain during wakefulness or in the phase of paradoxical sleep are more depolarized, i.e. can be “excited” more quickly than in the brain during deep sleep. The right and left hemispheres of the brain are more aligned during REM sleep, especially during lucid dreaming. REM sleep is punctuated by PGO (pontogeniculo-occipital) waves, pulses of electrical activity originating from the brain stem. These waves are observed in clusters approximately every 6 seconds for 1–2 minutes during the transition from deep sleep to paradoxical sleep. They show maximum amplitude after displacement in visual cortex and cause rapid eye movements paradoxical phase sleep. The brain energy used during REM sleep, as determined by the exchange of oxygen and glucose, is equal to or greater than the amount of energy used upon awakening. The speed in deep sleep is 11–40% lower.

Brain chemicals

Compared to slow-wave sleep, both wakefulness and paradoxical sleep involve increased use of the neurotransmitter acetylcholine, which can produce faster brain waves. The monoamine neurotransmitters norepinephrine, serotonin and histamine are completely unavailable. Injections of acetylcholinesterase inhibitors, which effectively increase the availability of acetylcholine, induce paradoxical sleep in humans and other animals, even during slow-wave sleep. Carbachol, which mimics the action of acetylcholine on neurons, has a similar effect. In awakening people, the same injections induce paradoxical sleep only if the monoamine neurotransmitters have already been used up. Two other neurotransmitters, orexin and gamma-aminobutanoic acid (GABA), promote wakefulness, attenuate deep sleep, and inhibit paradoxical sleep. Unlike abrupt transitions in electrical patterns, chemical changes in the brain exhibit continuous, periodic fluctuations.

Role of the brain stem

Neural activity during REM sleep is observed in the brainstem, particularly in the pontine tegmentum and locus coeruleus. According to the activation-fusion hypothesis, proposed by Robert McCarley and Allan Hobson in 1975–1977, control during REM sleep involves REM-on and REM-off neuron pathways in the brainstem. REM-switching neurons are predominantly cholinergic (i.e., includes acetylcholine); REM-off neurons activate serotonin and norepinephrine, which, among other functions, suppress REM-on neurons. McCarley and Hobson show that REM-on neurons actually stimulate REM-off neurons, thus providing a mechanism for cycling REM and deep sleep. They used the Lotka-Volterra equations to describe this cyclic inverse relationship. Kayuza Sakai and Michel Jouvet put forward a similar model in 1981. While acetylcholine appears in the cortex equally during wakefulness and REM sleep, it is observed in more high concentrations in the brain stem during REM sleep. The elimination of orexin and GABA may result in the absence of other excitatory neurotransmitters. A study in the 1990s using positron emission tomography confirmed the role of the brain stem. It also suggests that, within the forebrain, the limbic and paralimbic systems, typically associated with emotion, show greater activation than other areas. The areas of the brain activated during REM sleep are almost the opposite of those activated during deep sleep.

Eye movements

Most eye movements during REM sleep are actually less rapid than those typically seen in awake people. They are also shorter in duration and more likely to return to the starting point. About seven such returns are observed during one minute of REM sleep. While the eyes may move apart in slow-wave sleep, the eyes of a sleeper in paradoxical sleep move together. These eye movements follow pontogeniculo-occipital waves originating from the brain stem. Eye movements themselves may be related to the visual sense experienced in sleep, but the direct connection must be clearly established. It has been observed that congenitally blind people, who usually do not have visual images in their dreams, still have eyes that move during REM sleep.

Circulation, respiration and thermoregulation

In general terms, the body suspends homeostasis during the paradoxical sleep phase. Heart rate, heart pressure, minute cardiac output, blood pressure and breathing rate quickly become irregular as the body enters REM sleep. In general, respiratory reflexes, such as the response to hypoxia, are weakened. In general, the brain has less control over breathing; Electrical stimulation of breathing-related regions of the brain does not affect the lungs as it does during deep sleep or while awake. Fluctuations in heart rate and blood pressure tend to coincide with PGO waves and rapid eye movements, twitches, or sudden changes in breathing. Penile erection (nocturnal erection or NPT) typically accompanies REM sleep in rats and humans. If a man suffers from erectile dysfunction (ED) while awake but exhibits episodes of nocturnal erection during REM sleep, this indicates that erectile dysfunction is more likely to occur. psychological reason than physiological. In women, clitoral erection (nocturnal clitoral erection or NCT) causes a concomitant increase in vaginal blood flow and extravasation (i.e., lubrication). During normal nights of sleep, the penis and clitoris can remain erect for one hour to three hours and half the duration of REM sleep. Body temperature is not sufficiently regulated during REM sleep and thus organisms become more sensitive to temperatures outside their thermoneutral zone. Cats and other small furred mammals vibrate and breathe faster to regulate temperature during deep sleep, but not REM sleep. Due to the loss of muscle tone, animals lose the ability to regulate temperature through body movement. (However, even cats with pontine lesions that prevent muscle atonia during REM sleep do not regulate temperature through vibration.) Neurons that normally fire in response to cold temperatures—triggered for neural thermoregulation—are not activated during REM sleep. since they do this during deep sleep and wakefulness. Therefore, hot or cold ambient temperatures may reduce the proportion of REM sleep as well as the total amount of sleep. In other words, if the body is at the end of deep sleep and the temperature readings are outside a certain range, it will not enter REM sleep to avoid deregulation, allowing the temperature to slowly change towards the desired value. This mechanism can be “deceived” by artificially heating the brain.

Muscles

REM sleep atonia, almost complete paralysis of the body, is achieved through inhibition of motor neurons. As the body enters REM sleep, motor neurons throughout the body undergo hyperpolarization: their negative transmembrane potential decreases by an additional 2 to 10 millivolts, thereby increasing the threshold that a stimulus must exceed for them to fire. Muscle inhibition may result from unavailability of monoamine neurotransmitters, excess acetylcholine in the brainstem, and possibly mechanisms used for muscle inhibition during wakefulness. The medulla oblongata, located between the pons and the spinous process, has the ability to exert muscle inhibition across many organisms. Some localized muscle contractions and reflexes may be observed. The absence of REM sleep atonia causes REM sleep behavior disorder, in which sufferers engage in physical activities while dreaming. (An alternative explanation is that the sleeper is "sleep-acting": the muscle impulse precedes the mental representation. This explanation may also apply to normal sleepers, in whom signals to the muscles are suppressed.) (It should be noted that normal sleepwalking occurs during slow-wave sleep .) Narcolepsy, in contrast, involves excessive and unwanted REM sleep atonia—i.e. cataplexy and excessive daytime sleepiness while awake, hypnagogic hallucinations before entering slow wave sleep or sleep paralysis while awake. Other psychiatric disorders include depression, which is associated with disproportionate REM sleep. Patients with potential sleep disorders are usually diagnosed through a polysomnogram. Damage to the pons, which prevents REM sleep atonia, causes “REM sleep behavior disorder” in animals.

Psychology

Dream

REM sleep has been closely associated with dreams since its discovery. Waking sleepers during REM sleep is a common experimental method for obtaining dream reports; 80% of neurotypical people report some type of dreaming in these conditions. Sleepers awakened during REM sleep tend to give longer narrative descriptions of the dreams they experienced and rate the duration of dreams as longer. Lucid dreaming is reported most frequently during REM sleep. (In fact, they should be considered a hybrid state that combines essential elements of REM sleep and waking awareness.) The mental processes that occur during REM sleep most often have features dreams, including narrative structure, lucidity (experiential resemblance to waking life) and the integration of instinctive motives. Hobson and McCarley suggested that PGO waves, characteristic of “phasic” REM sleep, may provide the visual cortex and forebrain with electrical stimulation that enhances the hallucinatory aspects of dreaming. However, people awakened during sleep do not report significantly more bizarre dreams during phasic REM sleep compared to tonic REM sleep. Another possible connection between the two phenomena may be that the higher threshold of sensory cutoff during REM sleep allows the brain to subsequently move along unrealistic and specific thought chains. Some dreams can occur during the deep sleep phase. Light sleepers may experience dreams during stage 2 deep sleep, while heavy sleepers, upon awakening at this stage, are more likely to report “thinking” rather than “dreaming.” Some scientific efforts to determine the unique anomalous nature of dreams made during sleep have been forced to conclude that waking thinking can be no less bizarre, especially in conditions of decreased sensitivity. Because of dreaming during deep sleep, some sleep researchers strongly reject the importance of dreaming being associated with REM sleep. The prospect that the well-known neurological aspects of REM sleep are not themselves the cause of dreams suggests a need to re-evaluate the substantive neurobiology of dreaming. Some old guard paradoxical sleep researchers (Dement, Hobson, Jouvet), however, resist the idea that dreams are not related to REM sleep.

Creative skills

After awakening from REM sleep, consciousness is “hyperassociative”—more receptive to semantic instruction. People who awaken from REM sleep perform better on tasks such as anagrams and creative problem solving. Sleep facilitates the process by which Creative skills transform associative elements into new combinations that are practical and meet certain requirements. This occurs in REM sleep rather than deep sleep. This is unlikely to be related to memory processes, but is attributed to changes during REM sleep in cholinergic and noradrenergic neuromodulation. High levels of acetylcholine in the hippocampus suppress feedback from the hippocampus to the neocortex, while more low levels acetylcholine and norepinephrine in the neocortex stimulate an uncontrolled increase in associative activity in neocortical regions. This is the opposite of waking awareness, where high levels of norepinephrine and acetylcholine inhibit repetitive connections in the neocortex. REM sleep, through this process, enhances creativity by allowing "neocortical structures to reorganize associative hierarchies in which information from the hippocampus is reinterpreted in relation to previous semantic representations or nodes."

Duration

In a sleep cycle of less than 20 hours, the body alternates between deep sleep (slow, large, synchronized brain waves) and paradoxical sleep (fast, desynchronized waves). Sleep is observed in close connection with a large circadian rhythm, which influences sleepiness and physiological factors, based on internal clock body. Sleep can be distributed throughout the day or in clusters over one part of the rhythm: in nocturnal animals during the day and in diurnal animals at night. The body returns to homeostatic regulation almost immediately after the end of REM sleep. During a night's sleep, there are usually about four or five periods of REM sleep; they are quite short at the beginning of sleep and longer towards the end. Many animals and some people tend to wake up or dismantle a period of very light sleep for a short time immediately after a period of REM sleep. The relative amount of REM sleep varies greatly with age. A newborn baby spends more than 80% of his total sleep time in REM sleep. During REM sleep, the activity of brain neurons is quite similar to activity during wakefulness; for this reason, REM sleep is called paradoxical sleep. REM sleep typically accounts for 20–25% of adults' total sleep time: about 90–120 minutes of sleep a night. The first episode of REM sleep occurs approximately 70 minutes after falling asleep. Cycles last approximately 90 minutes, with each cycle including for the most part REM sleep Newborns spend more time in REM sleep than adults. The proportion of REM sleep then declines significantly during childhood. Adults tend to sleep less overall, but REM sleep takes about the same amount of time, and as a result, REM sleep takes up the majority of sleep time. REM sleep can be divided into tonic and phasic modes. Tonic REM sleep is characterized by feta rhythms in the brain; Phasic REM sleep is characterized by PGO waves and actual “rapid” eye movements. External stimulus processing is significantly inhibited during phasic REM sleep, and recent evidence suggests that sleepers have a more difficult time awakening from phasic REM sleep than from slow-wave sleep.

Effects of REM sleep deprivation

REM sleep deprivation significantly increases the number of attempts to enter REM sleep while asleep. On recovery nights, the subject enters stage 3 and REM sleep more quickly and exhibits REM sleep recovery, which tends to significantly increase time spent in REM sleep compared to normal levels. These findings are consistent with the idea that REM sleep is biologically necessary. Once deprivation is complete, mild psychological disturbances may develop, such as anxiety, irritability, hallucinations and inability to concentrate, and a decrease in appetite may occur. There are also positive effects of REM sleep deprivation. Some symptoms of depression are suppressed by REM sleep deprivation; aggression and eating behavior may intensify. High level norepinephrine is a possible cause of these results. The extent to which long-term REM sleep deprivation has psychological effects remains a matter of debate. Some reports suggest that REM sleep deprivation increases aggressive and sexual behavior in laboratory animals. Short-term REM sleep deprivation has been shown to improve certain types of depression, where depression is associated with an imbalance of certain neurotransmitters. Although sleep deprivation in general is a nuisance to most of the population, it has been repeatedly shown to alleviate depression, albeit temporarily. More than half of the subjects who showed such relief reported that it became ineffective after sleep the next night. Thus, methods such as changing sleep patterns for a period of time after a period of REM sleep deprivation and combining sleep pattern changes with pharmacotherapy to prolong the effect have been explored. Presumably, most antidepressants selectively inhibit REM sleep due to their effect on monoamines, an effect that is attenuated after long-term use. Sleep deprivation stimulates hippocampal neurogenesis to a greater extent than these antidepressants, but whether this effect is due to REM sleep is not known. Animal studies of REM sleep deprivation differ significantly from human studies. There is evidence that REM sleep deprivation has more severe consequences in animals than in humans. This may be because the duration of sleep deprivation in animals is significantly longer (up to seventy days), or that the various protocols used are more uncomfortable and unpleasant than protocols for humans. The “flower pot” method involves placing laboratory animals above water on a platform so small that they fall off it as soon as they lose muscle tone. A natural rude awakening, the results of which can cause changes in the body that necessarily exceed the simple absence of a sleep phase. Another method involves computer monitoring of brain waves, followed by automatic mechanical shaking of the cage as the animal enters REM sleep. Evidence suggests that REM sleep deprivation in rats impairs learning of new material but does not affect existing memory. In one study, rats did not learn to avoid a painful stimulus after REM sleep deprivation, which they could have done before the deprivation. No learning impairment was found in people who underwent one night of REM sleep deprivation. REM sleep deprivation in rats causes an increase in the number of attempts to enter the REM phase, and after deprivation, REM sleep is restored. In rats, as well as cats, REM sleep deprivation increases brain excitability (eg, electrical amplification of sensory signals), which lowers the threshold for paroxysms during wakefulness. This increase in brain excitability is similar in humans. One study also found decreased hindbrain sensory excitability. The hindbrain is generally less receptive to afferent pathway information because it is susceptible to increased amplification of these pathways.

REM sleep in animals

REM sleep is observed in all terrestrial mammals, as well as in birds. The amount of REM sleep and the timing of the cycle varies among animals; predators experience greater pleasure from REM sleep than prey. Larger animals also tend to spend more time in REM sleep, perhaps because the greater thermal inertia of their brains and bodies allows them to tolerate a longer thermoregulatory cessation. The period (a complete cycle of REM and deep sleep) lasts about 90 minutes in humans, 22 minutes in cats and 12 minutes in rats. In the womb, mammals spend more than half (50–80%) of the day in REM sleep.

Hypotheses regarding the functions of REM sleep

While the function of REM sleep is not well understood, several theories have been proposed.

Memory

Sleep in general helps memory. REM sleep may promote the retention of certain types of memory: particularly procedural, spatial, and emotional memory. REM sleep enhances subsequent intense learning in rats, particularly after several hours, and in some cases over several nights. Experimental REM sleep deprivation in some cases inhibits memory consolidation, especially for complex processes (eg, how to escape a complex maze). In humans, the best evidence for REM sleep's improvement in memory comes from learning routines—new ways of moving the body (such as jumping over a diving board) and new problem-solving techniques. REM sleep deprivation impairs verbal (i.e., non-procedural) memory only in more complex cases, such as remembering long stories. REM sleep clearly counteracts attempts to suppress certain thoughts. According to the dual sleep-memory hypothesis, the two main stages of sleep are associated with different types of memory. The midnight studies tested this hypothesis using memory tasks that began either before bedtime, in the middle of the night, or began in the middle of the night and were assessed in the morning. Slow wave sleep, part of deep sleep, is important for verbal memory. An artificial increase in deep sleep improves the recovery of memorized word pairs from memory the next day. Tucker et al showed that daytime light sleep, including only deep sleep, enhances verbal memory, but not procedural memory. The following hypothesis suggests that the two types of sleep interact to promote memory consolidation. Monoamine oxidase (MAO) inhibitors and tricyclic antidepressants may suppress REM sleep, but there is no evidence that these drugs cause memory impairment. Some studies show that monoamine oxidase inhibitors improve memory. Moreover, one case study of a subject who had short or absent REM sleep due to shrapnel damage to the brain stem did not find that his memory was impaired. (for a more detailed critique of the relationship between sleep and memory, see the link)) Closely related to reviews regarding the function of REM sleep in memory consolidation, Graham Mitchison and Francis Crick proposed in 1983 that, due to the inherent spontaneous activity, the function of REM sleep "is is to eliminate certain undesirable modes of interaction in a network of cells in the cerebral cortex,” a process they defined as “unlearning.” As a result, those memories that are relevant (the underlying neural substrate is strong enough to resist such spontaneous, chaotic activation) are further strengthened, while at the same time weak, temporary, “background” memories are destroyed. Memory consolidation during paradoxical sleep is specifically related to periods of rapid eye movement, which does not occur continuously. One explanation for this relationship is that electrical PGO waves that precede eye movements also influence memory. REM sleep may provide an opportunity for “unlearning” to occur in core neural networks involved in homeostasis that are protected from this “synaptic downscaling” during deep sleep.

Development of central nervous system stimulation as a primary function

Another theory, known as the Ontogenetic REM Sleep Hypothesis, argues that this stage of sleep (also known as active sleep in newborns) is important in part for brain development, perhaps because it provides the neural stimulation that newborns need to form mature neural connections and proper development of the nervous system. Studies examining the effects of active sleep deprivation have shown that deprivation early in life can lead to behavioral problems, persistent sleep disturbance, decreased brain weight, and abnormal rates of neuronal cell death. This theory was further supported by the fact that the amount of REM sleep in humans decreases with age, which also applies to other types (see below). One important theoretical implication from the Ontogenetic Hypothesis is that REM sleep may not have a vital function in the mature brain, i.e. when the development of the central nervous system is complete. However, because neural plasticity processes are not limited to the brain, REM sleep may be continuously involved in adult neurogenesis as a source of supportive spontaneous stimulation.

Protective immobilization: a precursor to dreams

According to Tsoukalas (2012), REM sleep represents an evolutionary transformation of the well-known defense mechanism, the feigned death reflex. This reflex, also known as animal hypnosis or feigning death, acts as a last resort defense against an attacking predator and involves generally immobilizing the animal so that it appears dead. Tsoukalas argues that the neurophysiology and phenomenology of this response shows striking similarities to REM sleep; for example, both responses are controlled by the brain stem, characterized by paralysis, sympathetic activation, and changes in thermoregulation.

Switching attention

According to the “scanning hypothesis,” the immediate properties of REM sleep are related to the shifting of attention in dream images. Against this hypothesis is that such rapid eye movements are observed in those born blind, as well as in fetuses, despite the lack of vision. Additionally, binocular REM sleep is inconsistent (ie both eyes may not be in the same direction at times) and thus lacks a fixation point. In support of this theory, researchers have found that in goal-directed dreams, eye movements follow the dream action, as determined by the relationship between eye movements and body movements in patients with REM sleep behavior disorder who perform dream actions.

Other theories

Other theories suggest that monoamine switching off is required so that monoamine receptors in the brain can be restored to reach full sensitivity. Moreover, if REM sleep is periodically interrupted, a person compensates for this with longer REM sleep, “restorative sleep,” as soon as possible. Some researchers argue that the preservation of complex brain processes such as REM sleep indicates that they serve an important function for the survival of mammals and birds. It satisfies important physiological needs, vital for survival to such an extent that long-term deprivation of REM sleep leads to death in experimental animals. In both humans and experimental animals, loss of REM sleep leads to severe behavioral and physiological abnormalities. Loss of REM sleep has been reported in a variety of natural and experimental infections. Survival of experimental animals is reduced when REM sleep is completely weakened during infections; This leads to the possibility that the quality and quantity of REM sleep in general is important for normal body physiology. The protective REM sleep hypothesis was proposed by Frederick Snyder in 1966. It is based on observations that REM sleep in several mammals (rat, hedgehog, rabbit, and rhesus monkey) is followed by a short awakening. This is not observed in cats or humans, although humans may be awakened more easily from REM sleep than from deep sleep. Snyder hypothesized that REM sleep periodically activates animals to scan their environment for possible predators. This hypothesis does not explain REM sleep muscle paralysis; however, logical analysis may indicate that muscle paralysis occurs for the purpose of preventing the animal from waking up completely unnecessarily, allowing it to easily fall into deep sleep. Jim Horne, a sleep researcher at Loughborough University, shows that REM sleep modern people compensates for the reduced need to wake up to search for food. Other theories include lubrication of the cornea, warming of the brain, stimulation and stabilization of neural circuits that were not activated during wakefulness, development of internal stimulation to promote CNS development, or a lack of targets as if it were randomly created by brain activation.

Discovery and further research

German scientist Richard Klu in 1937 first discovered a period of rapid electrical activity in the brain of cats. In 1944, Oglemeyer reported 90-minute sleep cycles showing erections in men lasting 25 minutes. At the University of Chicago in 1952, Eugene Azerinsky, Nathaniel Kleitman and William C. Dement discovered the rapid eye movement phases of sleep and linked them to dreams. Their paper was published on September 10, 1953. William Dement conducted the REM sleep deprivation study, experiments in which subjects were awakened whenever an electroencephalogram indicated the onset of REM sleep. He published the paper "Effects of Sleep Deprivation" in June 1960 ("REM sleep deprivation" became a more common concept as a result of subsequent research showing the possibility of deep sleep.) Neurosurgical experiments by Michel Jouvet and others in the next two decades introduced the concept of atonia and evidence of the importance Pontine tire (dorsolateral pons) in the initiation and regulation of paradoxical sleep. Jouvet et al found that disruption of the brainstem reticular formation inhibits this type sleep. Jouvet coined the name “paradoxical sleep” in 1959 and in 1962 published results showing that it can occur in cats when complete removal forebrain.

An article on the topic: “slow-wave sleep and REM sleep. which is better than the different stages of sleep” from professionals.

Sleep is one of the most mysterious processes that occur in human body. And one of the most significant, since we spend almost a third of our lives sleeping. And complete sleep deprivation, even for a relatively short period of time of a few days, can lead to neurotic disorders and imbalance of the entire body. Sleep is very difficult process, in which brain activity and vital body functions change. Scientists were able to identify the phases of slow and fast sleep, which have their own characteristics and purposes.

A little history

They tried to study sleep back in Ancient Greece. True, the explanation of what was happening at that time was more mystical than scientific. It was believed that during sleep, the immortal soul could rise to higher spheres and even descend to the kingdom of the dead. Slightly modified, this interpretation of sleep lasted in scientific circles until the mid-19th century.

But even after scientists established that sleep is caused by the functioning of the human nervous system and brain and has nothing to do with the immortal soul, it was impossible to conduct full-fledged research due to the lack of suitable equipment. It was only in the second half of the 20th century that it became possible to record nerve impulses emanating from muscles and the brain, which made it possible to determine the level of their activity.

A lot of things have been done with the help of electrical devices in the field of sleep. important discoveries. Rapid and slow-wave sleep were discovered, various types of insomnia were studied, and the processes occurring in the body during lethargic sleep were studied.

Scientists were able to reveal that human activity is regulated by circadian rhythms - daily alternations of periods of sleep and wakefulness, which continue to work even if it is impossible to navigate in time due to the lack of clocks and sunlight.

Computed tomography and magnetic resonance imaging have allowed us to study in more detail brain activity, which looks completely different during REM and slow-wave sleep. Interesting processes happen to a person when falling asleep, when the body and brain begin to slowly switch off and plunge into a state of deep relaxation, but at the same time certain parts of the brain continue to work.

But the most ambitious discovery was that the reactions of the brain and body to a vivid dream that a person sees in the REM phase are practically no different from reactions to real events. This means that a person literally “lives” his dream physically and mentally. But first things first.

Falling asleep

A person who wants to sleep is always easy to recognize, even if he tries to somehow hide his condition. Signs of drowsiness include:

A sleepy person begins to stretch, rub his eyes, and turn around in search of a position comfortable for falling asleep. This condition is associated with an increase in the concentration of a special hormone in the blood - melatonin. It gently inhibits the activity of the nervous system, promoting deeper relaxation and speeding up the process of falling asleep.

The hormone has virtually no effect on the quality of sleep itself. Melatonin is only a natural regulator of circadian rhythms.

The process of falling asleep in a healthy adult lasts from 20 to 40 minutes. If the duration of falling asleep remains constant for more than an hour, we can talk about the presence of one of the many forms of insomnia and it is better to take measures to eliminate it before it turns into chronic form. Natural sedatives, taking additional doses of melatonin, or proven folk remedies can help with this.

Slow phase

Having gone through the stage of falling asleep, a person plunges into slow-wave sleep. It gets its name from the slow rotation of the eyeballs that can be observed in a sleeping person. Although it's not just them. During slow-wave sleep, all vital functions of the body are inhibited - the body and brain relax and rest.

As they studied this phase, scientists made more and more new discoveries. As a result, it was discovered that in infants slow sleep has only two stages, and in children over 1-1.5 years old and adults - as many as four, through which the body sequentially passes:

All four stages of the slow phase take approximately one and a half hours, plus or minus 10 minutes. Of this, approximately a fifth of the time is occupied by deep and very deep sleep, and the rest is superficial.

Moreover, a person usually goes through the first stage of slow-wave sleep only after falling asleep, and when slow and fast sleep alternate during the night, it “falls out.”

Fast phase

Scientists have not fully figured out what REM sleep is, how such strange processes can occur in the body, and what significance it has for humans. If everything is more or less clear with slow sleep - this is a period of active recovery of the body and complete relaxation, then the reactions of the brain and the vital functions of the body during REM sleep are completely different.

During REM sleep, a person's eyeballs under closed eyelids begin to move quickly along a chaotic trajectory. From the outside it seems that a person is closely watching something. In fact, this is so, since it is in this phase that dreams appear. But eye movement is not the only and far from the main difference between REM sleep.

What was seen on the encephalogram, and later on the tomogram of the brain during the fast phase, so amazed scientists that it received another name: “paradoxical sleep.” All readings during this period may be practically no different from those taken in a state of active wakefulness, but at the same time the person continues to sleep:

In fact, the entire body is “turned on” in the dream as if it were a real event, and only the person’s consciousness is turned off. But if you wake him up at this moment, he will be able to tell the plot of the dream in great detail and at the same time will experience emotional experiences.

Interestingly, it is during REM sleep that changes occur hormonal levels. Some scientists believe that it is necessary for emotional “reset” and balancing of the endocrine system.

Having experienced exciting events again during sleep, a person then sends these memories to the subconscious, and they stop bothering him.

REM sleep also helps in regulating the level of sex hormones. Nocturnal erections, wet dreams and spontaneous orgasms occur during this phase. Moreover, they are not always accompanied by dreams of an erotic nature.

At the same time, most heart attacks or strokes occur, due to the fact that the relaxed heart and blood vessels are subjected to sudden stress.

At the beginning of the night, the fast phase does not last long - from 5 to 10 minutes, and a person spends most of the time after falling asleep in slow-wave sleep. But in the morning the phase relationship changes. The periods of REM sleep become longer and longer, and the periods of deep sleep become shorter and shorter, and at one point the person wakes up.

Proper awakening

An interesting fact is that a person’s activity and condition, especially in the first half of the day, depends on how he woke up. If he is awakened by external stimuli (alarm clock, bright light, sharp sounds, shock) during the slow phase of sleep, he still needs some time to “come to his senses.” In the first seconds, he may not even understand where he is, some parts of the brain are still so inhibited.

It is a completely different matter if the awakening occurs during REM sleep. The body is already alert and active, you just need to turn on your consciousness. A person who wakes up in this phase feels great, can quickly get out of bed and go about his business. At the same time, he perfectly remembers the last dream and can write it down or retell it.

The modern rhythm of life places high demands on the level of physical activity. Perhaps that's why in Lately So-called “smart alarm clocks” are becoming increasingly popular, which read body readings and send a signal just in the stage of REM sleep.

The advantage of such a device is that it greatly facilitates awakening, but the disadvantage is that it can wake a person up 20-30 minutes before the set time, since it begins to track sleep phases in advance, calculating the appropriate moment.

But even if you woke up easily, doctors do not advise jumping out of bed right away. Give the body 5-10 minutes for all organs and systems to smoothly start working. Stretch, lie down, tune in to the new day, go over your plans in your head again. And when you feel that you are completely ready for active actions, get up and move on to your morning routine.

Prevention of insomnia

Healthy quality sleep is considered to be a state in which a person quickly falls asleep and smoothly moves from one phase to another, waking up at the end of the night at his usual time on his own, without an alarm clock. Unfortunately, few people can boast of this today. Chronic fatigue, stress, poor nutrition, and negative emotions greatly reduce the quality of sleep and are becoming increasingly common causes of chronic insomnia.

To avoid this problem and the multiple troubles associated with it - from neuroses to serious psychosomatic diseases, try to take at least basic measures that can ensure normal quality of sleep:

And most importantly, do not reach for sleeping pills even if you have been unable to fall asleep for several nights in a row. Such drugs quickly become addictive and in most cases deprive a person of the rapid phase of sleep.

Under the influence of a sleeping pill, a “heavy”, very deep sleep without dreams occurs, which is very different from normal - after it the person still feels broken.

If problems with falling asleep or frequent awakenings at night have become protracted, you are often tormented by nightmares, or your loved ones say that you walk at night, go to the doctor. The problem cannot be solved without finding out the cause that provoked it. And this can only be done after examination and consultation with several specialists: a neurologist, an endocrinologist, a somnologist.

But in most cases, temporary insomnia occurs as a result of stress or severe fatigue and can be easily dealt with using folk remedies: warm baths, milk at night, relaxing massage, aromatherapy. No less important is positive attitude. You can significantly improve the quality of your sleep simply by weaning yourself from thinking about problems in the evenings.

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We now know that sleeping at night is difficult physiological process, including up to five cycles REM and NREM sleep. But more recently, in the 19th century, sleep was perceived by scientists as a phenomenon closed to study, in contrast to the waking state, which can be measured and observed.

You can assess the sleeping posture, measure his physical indicators: pulse, blood pressure, breathing rate, body temperature, but how to assess the fundamental processes of sleep itself?

The first experiments were based on awakening the subject, that is, on invading the sleep process.

However, through these studies, the understanding has been gained that sleep occurs in successive stages. Köllschütter, a German physiologist, established in the 19th century that sleep is deepest in the first hours, and later becomes more superficial.

A breakthrough in the history of sleep research was the discovery of electrical waves that originate in the brain and that can be recorded.

Scientists have the opportunity to observe, record and study phenomena that occur in a person’s sleep, without waking him up - using an electroencephalogram.

Numerous studies have found that A person's nighttime sleep consists of several alternating cycles of rapid and slow-wave sleep.

The cycle consists of four stages of slow-wave sleep and two stages of REM sleep.. At the beginning of the night's rest, slow-wave sleep predominates; in the morning the proportion of REM sleep increases.

slow sleep occupies 75 - 85% of all sleep and consists of:

naps,
sleepy spindles,
delta sleep,
deep delta sleep.

Many functions of our body change as we fall into sleep: during the stages of drowsiness and sleep spindles, the pulse becomes slower, blood pressure decreases, and blood flows slower.

As soon as the sleeper reaches delta sleep, the pulse quickens and the blood pressure rises.

REM sleep consists of two stages:

Emotional,
unemotional.

These stages replace each other several times, and the emotional phase is always longer.

If you display the depth of sleep using a curve, you will get several descents into deep sleep, followed by ascents into shallow REM sleep.

These ascents and descents take approximately an hour and a half.

Scientists suggest that the rhythm of one and a half hours is the main biorhythm and persists during wakefulness.

The phases of sleep do not replace each other directly, but through an intermediate state similar to drowsiness. This transitional stage in a healthy person takes up about 5 percent of all sleep.

When recognizing the stages of REM and slow-wave sleep important feature serves as a gradual relaxation of muscles or a decrease in muscle tone.

Adults have the following percentages between all sleep stages:

Napping – 12.1%,
sleep spindles – 38.1%,
delta sleep, – 14.2%,
deep delta sleep – 12.1%,
REM sleep – 23.5%

Differences between REM and NREM sleep.

NREM sleep has four distinct stages, and fast - two,

Eye movements in slow-wave sleep, smooth at first and completely freezing at the end of the stage, in REM sleep - the eyes move continuously,

State of the autonomic nervous system different in both stages.

In slow sleep we are growing faster: growth hormone produced by the pituitary gland is produced more actively in this phase.

Dreams are of a different nature.

In the fast phase, dream pictures are action-packed, brightly and emotionally colored, in the slow phase, the dream plot is calm or absent altogether.

Awakening.

If you wake a person in the middle of REM sleep, he will get up much easier and will feel much better than as a result of waking up in the slow phase.

Even if you've had enough time to sleep and you expect to feel a surge of strength and vigor, this will not happen if you wake up unsuccessfully at the beginning or in the middle of the slow-wave sleep cycle. In such a situation, you can hear: “Did you get up on the wrong foot?”

Apparently the cause of this condition is incomplete neurochemical processes that take place in slow-wave sleep.

Breath when falling asleep it becomes less frequent and louder, but less deep.

It slows down even more and becomes irregular in delta sleep.

Breathing in REM sleep is sometimes slow, sometimes frequent, sometimes with delays - this is how we react to the events of the dream we are watching.

Brain temperature decreases in slow-wave sleep, and in fast sleep, due to increased blood flow and active metabolism, it rises and sometimes exceeds the temperature during wakefulness.

Despite numerous differences, the stages of slow and fast sleep have a chemical, physiological, functional interdependence and belong to a single balanced system.

Regulation occurs in slow-wave sleep internal rhythms every brain structure, every organ, every cell. During REM sleep, harmonious relationships are established between these structures, organs, and cells.

Based on materials from the book “Three Thirds of Life” by A. Wayne.

Elena Valve for the project Sleepy Cantata

Sleep is an essential human need. Its importance cannot be underestimated. Without sleep, a person will not be able to exist normally, and hallucinations will gradually appear. Researches sleep special science– somnology.

Sleep functions

First of all, the main function of sleep will be rest for the body, for the brain. During sleep, the brain will work in a certain way, forming for the body special conditions. Under these conditions, the following should occur:

1. Rest of consciousness from daily activities.
2. Finding solutions to open problems.
3. Relaxation of body muscles.
4. Release of the hormone melatonin.
5. Stimulation of immunity at an adequate level.
6. Consolidation of acquired knowledge in memory.

As already mentioned, without sleep a person cannot exist normally. Sleep also performs the function of regulating biorhythms.

Sleep disorders such as: insomnia, nightmares, sleepwalking, sleep paralysis, Sopor, difficulties falling asleep will indicate that the person has any serious illnesses (most often of a neurological nature).

Stages of sleep. What do they have in common?

To date, scientists have found that there are 5 phases of sleep. Four of which are classified as slow-wave sleep, and one is classified as fast sleep.

When a person falls asleep, he enters the stages of slow-wave sleep, which vary in the degree of relaxation of the body and brain. Afterwards comes the REM sleep phase.

For proper rest, all phases must go through. In order for a person to wake up rested, he needs to get up after the REM phase, but in no case during the slow phase. If this happens, the person will get out of bed tired and irritated.

The most sound sleep, when it is extremely difficult to wake a person, will be observed in the middle of one of the sleep phases. During the period of falling asleep, a person can be very sensitive to surrounding stimuli, so for good sleep and the absence of insomnia, it is important to fall asleep in a quiet room.

The difference between slow-wave sleep and fast sleep

Different stages of sleep will be characterized by different indicators brain activity, consciousness, condition and regulation of muscles.

NREM sleep involves decreased brain activity and consciousness. During this phase, sleep paralysis occurs - the muscles are completely relaxed. This stage of sleep will be characterized by possible appearance solutions to problem situations in real life, but since the brain will have reduced activity at this time, people often retain residual memories of the dream, fragments of it, but do not remember it completely.

By the fourth stage of the slow phase, the time of the lowest brain activity begins. It is very difficult to wake a person at this time, pathological conditions, such as: sleepwalking, nightmares, enuresis occur precisely during this phase of sleep. At this time, dreams occur, but a person most often completely forgets them, unless he suddenly wakes up by chance.

The main function of the slow phase of sleep is to restore the energy resources of a sleeping person.

The fast phase differs from the slow phase, first of all, presence of rapid movements of the eyeballs. Interestingly, during the rapid phase of sleep, brain activity becomes similar to its activity in the waking state. At this time, you can observe muscle spasms of the limbs and twitching in the sleeping person, which is the norm.

During the REM phase of sleep, people always have vivid and memorable dreams, which they can recount in detail after waking up.

Some scientists say that for proper sleep, you need, first of all, the slow phase of sleep, and that the fast phase of sleep is a kind of rudiment. Other scientists say that this is fundamentally wrong - REM sleep has its own meaning.

Firstly, the significance of REM sleep dreams for the human psyche cannot be diminished. Psychologists, interpreting dreams, especially those that are frequently repeated, can give an accurate personal portrait of a person.

In dreams, a person can express himself, and sometimes a person realizes that he is sleeping, sometimes not, but this fact is very important for the human psyche.

In dreams, most often a person sees everyday reality transformed into symbols, so he can look at it, as they say, from the other side, which may lead to the solution of problems that are important to him.

Therefore, although radically different from each other, both phases of sleep are required for a good night’s rest; they complement each other perfectly.

How to get rid of sleep problems

It is very important to approach the process of falling asleep carefully - then problems with falling asleep will not arise. Difficulty falling asleep or insomnia can be avoided by following certain tips:

1. A person should go to bed only when he wants to fall asleep.
2. If a person cannot fall asleep, he should switch to some other activity until the desire to sleep appears.
3. The room intended for rest should be quietly cool for comfortable falling asleep.
4. The room should be dark - this is the main condition for the production of the sleep hormone.

In order to avoid night fears, you will need to avoid watching programs that excite the nervous system, overeating, good action will take herbal sedatives and chamomile tea.

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

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

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

Sleep duration according to age

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

At different ages, people need different amounts of sleep:

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

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

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

The value of sleep by hour

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

Time	The value of sleep
19-20 hours	7 o'clock
20-21h.	6 hours
21-22 hours	5 o'clock
22-23 hours	4 hours
23-00 h.	3 hours
00-01h.	2 hours
01-02 hours	1 hour
02-03 hours	30 minutes
03-04 hours	15 minutes
04-05 hours	7 minutes
05-06 hours	1 minute

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

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

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

Features of awakening in each phase of sleep

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

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

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

However constant shortage REM sleep can be detrimental to mental health. It is this phase that is necessary to restore neural connections between consciousness and subconscious.

Phases of sleep in humans

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

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

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

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

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

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

Slow (deep) sleep

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

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

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

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

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

Stages of slow-wave sleep

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

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

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

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

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

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

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

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

Stages of REM sleep

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

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

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

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

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

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

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

Sequence of sleep stages

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

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

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

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

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

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

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

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

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

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

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

Rules for healthy sleep

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

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

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

NREM and REM sleep

NREM and REM sleep are different in their bioelectrical activity brain

Recording brain biocurrents in the form of an electroencephalogram (EEG) gives a peculiar pattern characteristic of various conditions. During slow-wave sleep, the EEG shows

slow waves of large amplitude, followed by fast rhythms during REM sleep. Differences between sleep stages are not limited to EEG data.

slow sleep

During slow sleep, breathing and pulse become slower, muscles relax, and during this period the so-called physical activity of a person decreases.

REM sleep

During the REM sleep phase, the breathing rate and heart rate increase, motor activity increases, and movements of the eyeball are clearly visible behind closed eyelids. These so-called rapid eye movements - characteristic feature this phase, hence another name for it: REM, after the first letters of the English words Rapid eye movements. At this moment, the sleeper dreams. An interesting fact has been established: waking up a sleeper during REM sleep, despite signs of more superficial sleep, increased breathing and heart rate, and EEG rhythm, is much more difficult than during slow-wave sleep. Therefore, the REM sleep phase is also called paradoxical sleep (respectively, slow-wave sleep is orthodox).

REM sleep never occurs immediately - it is recorded only after a certain duration of the slow-wave sleep phase. REM sleep is very important for a person’s mental state. When sleep patterns were studied in volunteers who were awakened for 3-4 nights in a row before the onset of the REM phase, they began to develop mental disorders, despite the overall sufficient duration of sleep.

Night sleep

Typically, nighttime sleep consists of a strict alternation of 4-6 completed cycles, each of which begins with slow sleep and ends with REM sleep. The normal duration of any cycle is from 60 to 90 minutes, but if at the beginning of the night REM sleep lasts only a few minutes, then by the morning its duration is about half an hour. In this case, it is necessary to combine these cycles, characterized by different ratios of sleep phases, with a certain hormonal level and temperature rhythm, changing from evening to morning. This is why certain hours of the day are so important for sleep. And it is no coincidence that sleeping during the day, as a rule, does not give the same refreshing effect as sleeping at night.

Another interesting point is that every healthy person dreams, but only those who wake up in the first 15 minutes after REM sleep remember them. It turned out that those who have a good memory dream. The brighter and more imaginative the dreams, the more complete the sleep. According to some scientists, one of the reasons for this is that during sleep, information received during the day may be actively processed. Thus, in the slow-wave sleep phase, information received during the day is processed, and in the REM sleep phase, which is characterized by dreams with the inclusion of fantastic unreal components, both protection from external stimuli and mental activity are carried out.

REM sleep plays a significant role in the process of learning and memorizing various information. Thus, among students actively studying foreign language, we can identify a group of young people who memorize new words very quickly and correctly. Unlike students with poor memorization ability, they have a longer duration of REM sleep.

The whole dream is divided into two fundamentally various types- This is slow sleep and rapid sleep. In turn, slow-wave sleep is divided into 4 phases. It turns out that there are only 5 different phases of sleep.

slow sleep

It is also called the dormancy stage. It is characterized by thinking and experiencing problems that arise during the day. The brain, by inertia, tries to find a solution to the problems it was working on while awake. A person can see images that implement a solution to a problem.

There is a further decrease in muscle activity, pulse and breathing slow down. The brain gradually stops working. This stage is characterized by short bursts of auditory sensitivity. Several times a minute a person is in a state where it is very easy to wake him up.

Is transitional. The difference between stages three and four of sleep is the number of delta oscillations. But we will not delve into such details.

Characterized by the deepest sleep. It is considered the most important, since at this time the brain receives the most complete rest and restores its performance. In the fourth stage of sleep, it is difficult to wake a person. Cases of talking in a dream or sleepwalking occur precisely in this phase.
The first two phases are considered shallow slow-wave sleep, and the second two are considered deep sleep. NREM sleep is also called orthodox sleep or non-REM sleep.

On the website http://androidnetc.org/category/neobxodimye you can download applications for android. For example, one of the proposed Sleep Time apps will analyze your body's vibrations and determine what phase of sleep you are currently in. When the time of awakening comes, the most appropriate moment for your awakening will be chosen. Lots of useful apps! Visit the site and see for yourself.

Rapid eye movement sleep (REM sleep)

This stage is also called REM sleep (from the English rapid eye movements, which means “rapid eye movements”). As you may have guessed, REM sleep is characterized by accelerated movements of the eyeballs under closed eyelids - this is the first fundamental difference from slow sleep.

The second difference is that in the REM sleep phase the brain does not rest at all, but on the contrary, it is activated. The heart rate also increases, but the large muscles are completely relaxed.

And the most interesting thing is that in the REM sleep phase it is most difficult to wake a person, although his state is closest to the state of wakefulness. That's why REM sleep is also called paradoxical sleep.
The purpose of REM sleep is not entirely clear. There are several assumptions about this:

1. During the REM sleep stage, the brain sorts out the information received.
2. The brain analyzes the environmental conditions in which the organism is located and develops an adaptation strategy. Indirect confirmation of this judgment is the fact that in newborns REM sleep is 50%, in adults - 20-25%, in older people - 15%.

But there is one fact that does not cause controversy - the most vivid dreams come to us in REM sleep! In other stages, dreams are also present, but they are blurred and we remember them very poorly. Scientists also say that you will only remember a dream well if you wake up in the REM phase.

Sequence of sleep stages

Sleep begins with phase 1, which lasts approximately 10 minutes. Then the 2nd, 3rd, and 4th phases follow sequentially. Then in reverse order- 3rd, 2nd and the REM sleep phase begins. Together they form a cycle that repeats 4-5 times a night.

This changes the duration different phases from cycle to cycle. In the first cycle, REM sleep is very short, longer time occupies deep slow-wave sleep. But in the last cycles there may be no deep sleep at all. Typically one cycle is 90-100 minutes.

Now comes the fun part. Your well-being depends on what phase of sleep you wake up in. The worst place to wake up is deep sleep. When you wake up from a deep sleep, you will feel groggy.

It is best to wake up after the end of the REM sleep phase, that is, at the beginning of the first or second phase. Waking up from REM sleep is not recommended.
Now you probably have a question about how to make sure you wake up in the right phase.

I will express only one thought on this matter. As already mentioned, it is quite difficult to wake a person in the deep sleep stage. So if your sleep is interrupted in a natural way, and not the sound of an alarm clock, then you are most likely to wake up in the right phase.

Now a little about the importance of fast and slow sleep. Some scientists say that REM sleep is a relic of the past, supposedly a person does not need it, just like the appendix.

The following facts are cited in support of this statement:

If you forcibly limit the duration of sleep, then the duration of the deep phase of sleep practically does not change; the brain primarily reduces the duration of REM sleep.

But this only proves that deep sleep is more important than fast sleep - no more!

Experiments have been conducted where people were completely deprived of REM sleep for two weeks. However, their health did not deteriorate in any way.

Two weeks is not that long, considering that some people can live that long without sleep at all.

But other scientists conducted experiments on rats. As a result, after 40 days without REM sleep, the rats died.

The sleep process is a very little studied phenomenon. In the future, sleep scientists will have to find answers to many controversial questions.
Well, we need to take care of our sleep and lead healthy image life!