What is slow and REM sleep: comparison and differences. How sleep phases affect human health and what is the secret of good sleep Fast and slow sleep biological significance

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

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

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

Sleep duration according to age

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

At different ages, people need different number of hours to sleep:

Most of all, unborn children sleep 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 old 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.
Junior pupils (6-13 years old) - 9-11 hours.
Teenagers need 8-10 hours of night rest.
Adults (18 to 65 years old) - 7-9 hours.
Elderly people, from 65 years old - 7-8 hours.

Old people are often tormented by insomnia due to ailments and physical inactivity during the day, so they sleep for 5-7 hours, which in turn affects their health in a bad way.

The value of sleep by the hour

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

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

Our ancestors went to bed and got up in the sun... A modern person goes to bed not earlier than one in the morning, the result is chronic fatigue, hypertension, oncology, neuroses.

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

In some southern cultures there is a tradition of daytime sleep (siesta), and it is noted that the number of cases of stroke and heart attack there is significantly lower.

Features of awakening in each phase of sleep

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

When it is better for a person to wake up in terms of sleep phases, how easily awakening will pass, depends on in which phase his sleep was interrupted.

During deep delta sleep, awakening is the most difficult due to incomplete neurochemical processes taking place in this stage. And here it is easy enough to wake up in REM sleep, despite the fact that during this period the most vivid, memorable and emotional dreams are dreamed.

However, a persistent lack of REM sleep can be detrimental to mental health. It is this phase that is necessary for the restoration of neural connections between consciousness and subconsciousness.

Sleep phases in humans

The features of the brain and the change in its electromagnetic waves were studied after the invention of the electroencephalograph. An encephalogram clearly shows how a change in brain rhythms reflects the behavior and state of a sleeping person.

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

Each cycle consists of 4 phases of slow sleep, associated with a gradual decrease in human activity and immersion in sleep, and one - fast.

REM sleep predominates in the initial sleep cycles and gradually decreases, and the duration of REM sleep increases in each cycle. From cycle to cycle, the threshold of a person's awakening changes.

The duration of the cycle from the onset of NREM sleep to the end of REM sleep in healthy people is about 100 minutes.

Stage 1 accounts for 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 unequivocally how long deep sleep should last, because its duration depends on which sleep cycle the 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 slow, or orthodox, sleep phase is divided into 4 stages: naps, sleep spindles, delta sleep, deep delta sleep.

Signs of slow 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 by the end of the phase.

At the same time, dreams are little-emotional or absent, on the encephalogram an increasing place is occupied by long and slow waves.

Previously, it was believed that during this time the brain is resting, but the study of its activity during sleep has disproved this theory.

Stage of slow sleep

In the formation of slow wave sleep, the leading role is played by such parts of the brain as the hypothalamus, suture nuclei, nonspecific thalamic nuclei and the inhibitory center of Moruzzi.

The main characteristic of slow 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 an accumulation of energy in the body as opposed to catabolism, which consumes it.

The anabolic processes of slow wave sleep begin at the 2nd stage, 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 phase of deep sleep.

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

Actually falling asleep is preceded by drowsiness: a decrease in motor activity and level of consciousness, dry mucous membranes, sticking eyelids, yawning, distraction of attention, decreased sensitivity of the sensory organs, slowing of heart contractions, an irresistible desire to lie down, second lapses in sleep. This is how the active production of melatonin in the pineal gland manifests itself.

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 show an increasing loss of consciousness.

Slumber, or Non-REM(REM - from English rapid eye movement) - the 1st stage of falling asleep with half-asleep dreams and visions similar to sleep. Slow eye movements begin, the body temperature decreases, the heart rate slows down, on the brain encephalogram, the alpha rhythms accompanying wakefulness are replaced by theta rhythms (4-7 Hz), which indicate mental relaxation. In such a state, a person often comes to a solution to a problem that he could not find during the day. It is quite easy to get a person out of slumber.
Sleepy spindles- of medium depth, when consciousness begins to turn off, but the reaction to being called by name or crying of your child persists. The sleeping person'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 often and become wider in amplitude, and subside.
Delta- without dreams, in which deep and slow delta waves with a frequency of 1-3 Hz and a gradually decreasing number of spindles are visible on the brain encephalogram. The pulse quickens a little, the respiratory rate increases with its shallow depth, the blood pressure decreases, and the eye movements slow down even more. There is a blood flow to the muscles and an active production of growth hormone, which indicates the restoration of energy costs.
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). Even odor sensitivity is absent. The sleeping person's breathing is rare, irregular and shallow, the movements of the eyeballs are almost absent. This is the phase during which it is very difficult to wake a person up. 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 sees 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 completeness of this stage of sleep affects the ability to memorize information.

REM sleep stages

From the 4th stage of sleep, the sleeper briefly returns to the 2nd, and then the state of REM sleep (REM-sleep, or REM-phase) sets in. 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 a low amplitude, as during wakefulness, but the neurons of the spinal cord are completely disabled to prevent any movement: the human body becomes as relaxed as possible, muscle tone drops to zero, especially in the area of the mouth and neck ...

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

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

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

In this phase, the information received during the day is corrected between consciousness and subconsciousness, the process of distributing the energy accumulated in the slow, anabolic phase is underway.

Experiments on mice confirm that REM sleep is much more important than slow sleep... That is why awakening in this phase by artificial means is unfavorable.

The sequence of stages of sleep

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

Sleep in newborns, for example, is more than 50% REM, only by 5 years, 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 fast phase decreases to 17-18%, and the delta sleep phases can come to naught: 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 a slight and brief oblivion or half asleep without dreams) or go without sleep at all.

Some have numerous and prolonged awakenings, due to which a person is in complete confidence that he has not closed his eyes during the night. At the same time, each of them can wake up not only during the phase of REM sleep.

Narcolepsy and apnea are diseases that exhibit atypical sleep stages.

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

Apnia is characterized by sudden cessation of breathing during sleep. Among the reasons - a delay in the respiratory impulse coming from the brain to the diaphragm, or too strong 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 makes the sleeping person wake up.

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

With apnea, it is very dangerous to use sleeping pills, it can provoke death from respiratory arrest during sleep.

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 case of manic conditions, the REM stage is reduced to 15-20 minutes overnight.

Healthy sleep rules

Adequate sleep means health, strong nerves, good immunity and an optimistic outlook on life. You should not assume that time is useless in a dream. Lack of sleep can not only be detrimental to 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:

Stick to a bedtime and wake up schedule... It is best to go to bed no later than 23 hours, and the entire sleep should take at least 8, ideally 9 hours.
Sleep must necessarily capture the period from midnight to five in the morning, during these hours the maximum amount of melatonin, the hormone of longevity, is produced.
Do not eat 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.
Walking in the evening will help you fall asleep faster.
If you have difficulty falling asleep, it is advisable to take a warm bath before going to bed with an infusion of soothing herbs (motherwort, oregano, chamomile, lemon balm) and sea salt.
Before going to bed, be sure to ventilate the room.... You can sleep with the window ajar and with the door closed, or open the window in the next room (or in the kitchen) and the door. In order not to catch a cold, it is better to sleep in socks. The temperature in the bedroom should not drop below +18 C.
It is more useful to sleep on a flat and hard surface, and use a roller instead of a pillow.
The position on the stomach is the most unsuccessful for sleeping, the position on the back is most useful.
After waking up, a little physical activity is desirable: charging or jogging, and if possible, swimming.

A sleepless person often faces problems of poor health, lack of strength. He loses efficiency, and the functionality of all body systems deteriorates. Night rest is a physiologically complex process. It consists of 5 slow and fast phases constantly changing each other. At this time, a person has time not only to relax, but also to rethink the information accumulated during the day. It is important for everyone to know what slow sleep is, since it is it that allows you to fully recuperate.

The first experiments to study night rest as a physiological process consisted of interrupting it at a certain time. After that, the subject's feelings were recorded. They made it possible to establish that night rest consists of phases that change sequentially. The first scientist to study sleep was A.A. Manasein. She determined that sleep at night is more important for a person than food.

In the 19th century, the scientist Kellschütter found that a stronger and deeper sleep is in the first hours after falling asleep. Towards morning it becomes superficial. The most informative studies became after they began to use an electroencephalogram, which records electrical waves emitted by the brain.

Distinctive features of slow sleep

The slow phase takes up about 85% of the total sleep volume. It differs from the quick rest phase in the following features:

Consists of 4 stages.
At the moment of falling asleep, the movements of the eyeballs are smooth. At the end of the stage, they freeze.
Dreams at this stage do not have a vivid plot. For some people, they may be absent altogether.
Disruption of the slow-wave sleep phase is accompanied by a person's irritability, he gets up tired, cannot sleep. His working capacity falls, his state of health worsens. This happens due to the fact that not all neurochemical processes are completed.
Breathing and pulse becomes slow, there is a decrease in blood pressure, body temperature.
At this stage, the muscles are completely relaxed.

Advice! As for REM sleep, a person wakes up at this stage without consequences for the body. There is an activation of all life processes: an increase in heart rate, respiration. This resting phase is shorter.

The value of deep sleep

In order for a person to get enough sleep, he must rest properly. During slow wave sleep, growth hormone is synthesized, intensive cell regeneration. The body is able to relax well, renew its energy supply. At this stage, the rhythms of all brain structures are regulated.

An adult has the ability to rebuild his immune system. If you sleep properly, a sufficient amount of time, then the metabolism improves and the elimination of toxins from the tissues of the body. In the phase of slow sleep, the information received during the day is actively processed, and the material studied is consolidated.

Elements that make up the orthodox phase

The stage of slow sleep consists of several elements, which can be read about in the table:

Item name	Characteristic
Nap	In this time interval, there is a revision and conjecture of ideas that have emerged during the day. The brain tries to find a solution to the accumulated problems. There is a decrease in heart rate, breathing
Sleepy spindles	Here consciousness turns off, but these periods alternate with an increase in visual and auditory sensitivity. At this time, a person can be easily awakened. At this stage, there is a decrease in body temperature
Delta sleep	This phase is considered to be transitional to the deepest sleep.
Deep delta sleep	During this period, a person may have dreams, his energy decreases. When awakening is needed, this process is a severe stress for the body. Deep sleep occurs within an hour and a half after the start of the first phase

These stages have a certain percentage:

Doze: 12.1%.
Sleepy spindles: 38.1%.
Delta Sleep: 14.2%
Deep delta sleep: 23.5%

REM sleep takes 23.5% of the total time.

Duration of the slow stage per night

Many users want to know how long slow-wave sleep should last per night in order to eliminate sleep deprivation. This cycle begins immediately after the transition of the sleeping person into unconsciousness. Further, a deep phase begins. There is a disconnection of sensory perception, dulling of cognitive processes. Normally, the nap period can last 15 minutes. The last three stages take about an hour. The total duration of the slow phase (excluding the alternation with REM sleep) is 5 hours.

The length of this period is influenced by age. In a child, this phase lasts 20 minutes, in adults up to 30 years old - 2 hours. Further, it decreases: from 55-60 years - 85 minutes, after 60 years - 80. Healthy rest should take at least 6-8 hours a day.

It should be noted that the sleep rate per night for each person is different. Someone can sleep quickly and 4-5 hours will be enough for him, and 8-9 hours will not be enough for someone. Here you need to pay attention to your feelings.

It's important to know! Determining the exact time required for a night's rest is done by trial. This will take 1-2 weeks. But the slow phase must not be constantly disturbed.

Human condition during deep sleep

At night, the deep stage will be accompanied by complete relaxation of the muscular system and the brain. The conduction of nerve impulses changes, sensory perception is dulled. There is a slowdown in metabolic processes, the work of the stomach and intestines.

During this period, the brain requires less oxygen, the blood flow becomes less active. A proper night's rest will be characterized by a slowdown in tissue aging.

Reduction of the slow phase: what is the danger

Depending on how long the slow sleep phase lasts, the person will have good health and performance. Its reduction is fraught with the emergence of serious health problems: the clarity of consciousness is lost, constant drowsiness appears. Regular disruption of the normal duration and structure of sleep leads to chronic insomnia. A person has the following problems:

increased fatigue;
immunity falls;
irritability increases, mood often changes;
metabolic processes are disrupted, mental functions, attention are dulled;
the work of the endocrine system becomes problematic;
the risk of developing diseases of the heart and blood vessels increases;
efficiency, endurance falls;
insulin synthesis fails.

Attention! A decrease in the amount of sleep leads to the development of atherosclerosis, diabetes mellitus, and oncological pathologies. Comparative analysis has shown that the slow and fast phases of night rest are equally important, although their characteristics will differ.

Regardless of whether a man or a woman has a disturbed sleep structure, how much a person sleeps, if he does it wrong, then rest will not give the desired result. To improve its quality, you need to follow the following recommendations of specialists:

Stick to a bedtime schedule. Better to go to bed no later than 11 pm. At the same time, it is advisable to wake up no earlier than 7 am (this indicator is individual).
Before going to bed, you need to ventilate the room. The temperature in the bedroom should not exceed 22 degrees. To improve the quality of your sleep, you can take an evening walk in the fresh air.
A few hours before rest, you should not eat food that requires a long digestion time. As a last resort, you can drink a glass of warm milk.
Night rest should include a period from midnight to 5am.
Drinking coffee, strong tea or alcohol in the evening is strictly prohibited.
If it is difficult for a person to fall asleep, then he can drink tea with the use of soothing herbs (motherwort, valerian), take a relaxing bath with sea salt. Aromatherapy often helps sleep.
It is important to choose a comfortable resting position.
Orthopedic resting devices should be preferred. The mattress should be flat and firm. Do not use a high headboard.
The room should be quiet and dark at night.
After waking up, it is better to take a contrast shower or do light gymnastics.

A proper night's rest, respecting its structure, is the key to good health and well-being. A person wakes up rested, efficient, in a good mood. Systematic lack of sleep will lead to serious disruptions in the functionality of the body, from which it is not easy to get rid of.

Hello dear blog readers! I don't know about you, but I have always been interested in the topic of sleep. I've heard a lot of all sorts of theories and guesses about him: about slow sleep, and about fast sleep, and about all kinds of its phases. But I have never "tested it" myself. I heard, and that's it. And to dig deeper all the mind did not have enough hands did not reach 🙂 (although, I already wrote an article about healthy sleep before - it means I dug a little).

So today I decided to improve and fill this gap in knowledge. Well, as usual, I openly share all the interesting information that I find on the Internet with you.

Stage classification

So, the first thing I came across is the simplest classification that we have known since school. According to her, the stages of sleep are divided into:

fast;
and slow.

Moreover, each stage has its own "substages". So, quick sleep is divided into:

emotional;
unemotional.

A slow on:

drowsiness;
sleepy spindles;
delta sleep;
deep delta sleep.

I do not see the point of delving into each of these points - there is little interesting there (mainly the difference in the activity of brain waves and all that). Better take a look at this table of differences between stages that I put together for you:

Well, now let's define what happens to us when falling asleep and how all these stages alternate with each other. Now that's a little more interesting, isn't it?

Sequence of stages

1) After we went to bed and began to fall asleep, it is activated first phase of sleep(or the stage of drowsiness).

It lasts about 5-10 minutes, no more. As a rule, in this short period of time, our brain does not have time to “calm down” and is still quite active: it solves the last tasks, problems - in general, it works by inertia 🙂

2) Then follows second phase of slow wave sleep.

Here, there is a decrease in muscle activity, a slowdown in breathing and heart rate. At the same time, the eyes remain motionless. At this stage, there are a number of short moments in which the person is easiest to wake up. This stage of sleep lasts about 20 minutes.

3) The third and fourth phases of sleep are very similar to each other and last about 30-45 minutes (the difference is only in the number of delta oscillations - that's why they are called "delta" and "deep delta" dreams).

4) After that, the person returns again into the 2nd stage of slow wave sleep(described above), and after that it goes into the first part of the fast * (very short - only about five minutes).

* Note that REM sleep occurs only after passing all 4 (or rather five: 4 forward, and one back :)) - phases of slow.

This whole sequence of four points described above is called cycle... The time of the first such cycle is about 90-100 minutes.

What are we doing the other 5-6 hours?

It's simple: the rest of the time, these phases are repeated under only one condition: the share of REM sleep increases due to a decrease in the share of slow sleep (in the morning, the stage of REM sleep can last an hour, as it is written in Wikipedia). With full healthy rest, there are about five such cycles.

Wow, well, it seems that I explained everything clearly 🙂 Now that we know what is going on and for what, let's try to answer the question: “ when is the best time to wake up? ».

So when is the best time to wake up?

So I have found several ways to determine the best rise time.

1) Here is this resource. Based on algorithms known only to them, the calculator calculates the optimal time to wake up. All you need is to drive in the time to fall asleep and press "calculate".

For example, if I fall asleep at 23:00 (as usually happens), it is best for me to wake up at 6:00. Who knows, maybe this is true (because I woke up today at 6:25 and the awakening was not the easiest - fortunately, a contrast shower helped out) 🙂 Tomorrow I'll try to get up at 6:00.

2) You can also use this table here. I do not know who its author is, but everything is presented very clearly and intelligibly - many thanks to him for that.

REM sleep phases are highlighted in green here, slow sleep phases are highlighted in red. And if you believe this scheme, then it is best to wake up at the very end of the first phase - moreover, it is REM sleep. This time is even marked with an alarm clock.

According to the timeline (x-axis), it is best to wake up seven hours after falling asleep. In principle, everything is the same: if you look at the screenshot above (point 1), then, falling asleep at 23:00, it is best to get up at 6:00 - here the picture is the same. Well, everything, tomorrow I will get up at exactly 6:00! If I don’t forget, I’ll write you about my successes 🙂

Did you know?

Well, we have analyzed the stages of sleep, we have determined the best time for awakening. What are we going to do now? Oh, I have an idea! Let's find out how animals sleep!

Did you know, what:

cats sleep 16 hours a day;
giraffes, before falling asleep, kneel and bend their heads around their legs;
dolphins and cetaceans have the ability to one-sided sleep (this is when one hemisphere of the brain is asleep and the other is awake). In marine inhabitants, this is explained by the need to surface in order to take in air during sleep.
birds can sleep not only while standing, but even on the fly! (migratory birds have developed an interesting mechanism: every 15 minutes one individual flies into the very center of the flock and falls asleep, only slightly working with its wings. It hovers in the air mainly due to the air flow of the flock. After a kind of rest, it returns, giving way to others) ...

Agree that in our case, everything is not so bad - when there is a soft bed, a blanket and a pillow under your head 🙂

Let's summarize

Well, like he told everything about what he wanted. I hope this article is not too confusing, although sleep phases are a tricky thing.

That's all. I wish you success, dear readers, and all the best. Keep track of your health, both physical and mental, and do not forget to visit the pages of my blog.

To be honest, I still don't understand the intentions of the author of this video. Well, why, why wake the sleeping tit, and even in this way? 🙂

It is a physiological process in which a person (as well as mammals, fish, birds and some insects) is in a state that is fundamentally different from the state of wakefulness. This state is characterized by an altered consciousness, a decrease in the level of brain activity and reactions to external stimuli. Natural sleep differs significantly from similar conditions such as coma, suspended animation, fainting, hypnosis-induced sleep, and lethargic sleep. Along with sleep in the usual sense of the word (i.e. sleep at night), certain cultures allow the existence of the so-called daytime rest or siesta. Naps are part of the tradition of many peoples. In accordance with the results of ongoing studies, regular afternoon nap can significantly reduce (by almost 40%) the percentage of the risk of a heart attack. In a word, sleep is the most important element of human life and, at the suggestion of researchers, since 2008, the Day of Sleep is celebrated every 3rd Friday of the first month of spring.

Basic sleep functions

Sleep helps the body get the rest it needs. During sleep, the brain processes the information accumulated during the day. The so-called slow-wave sleep allows you to better assimilate the studied material and fix it in your memory. REM sleep provides the ability to model upcoming events at the subconscious level. An important function of sleep is also to restore the human immune system by activating the activity of T-lymphocytes, which resist viral infections and fight colds.

Physiology of the sleep process

Healthy sleep can last from 4 to 8 hours. However, these indicators are quite subjective, since the duration of sleep depends on the person's physical fatigue. A significant amount of work done during the day may require a longer night's rest. Normal sleep is cyclical and is required by the human body at least once a day. Sleep cycles are called circadian rhythms. The circadian rhythms are redefined every 24 hours. The most important factor in sleep is light. It is on its natural cycle that the concentration of photo-dependent proteins in the body depends. Typically, the circadian cycle is related to the length of daylight hours. Immediately before sleep occurs, a person feels drowsy, his brain activity decreases, and a change in consciousness is also noted. In addition, a person who is in a sleepy state has a decrease in sensory sensitivity, a reduction in heart rate, yawning, and, in addition, a decrease in the secretory function of the lacrimal and salivary glands. Another physiological feature of sleep is a process called "vegetative storm", i.e. when various forms of arrhythmias are observed, an increase or decrease in blood pressure, increased blood supply to the brain and secretion of the adrenal glands, erection of the clitoris and penis.

The structure of the sleep process

Any dream is divided into several stages, which are repeated with a certain pattern throughout the night (of course, provided that the daily schedule is absolutely normal). Each stage of sleep directly depends on the activity of a particular brain structure. The first stage of sleep is slow-wave sleep (Non-REM). The duration of Non-REM sleep is 5 to 10 minutes. This is followed by a second stage, which lasts about 20 minutes. Over the next 30-45 minutes, 3 and 4 more stages of sleep are noted. Then the person again falls into the second stage of slow wave sleep, after which REM sleep occurs (1st episode). This is about 5 minutes. All of the above stages are the first sleep cycle, which lasts from 90 to 100 minutes. After that, the cycle repeats again, but in this case, the stages of slow sleep are reduced, and REM, on the contrary, increases. Typically, the last sleep cycle ends with a REM sleep episode lasting about 1 hour in some cases. Adequate sleep includes 5 complete cycles. The sequence according to which one stage of the sleep cycle replaces another, as well as the duration of each cycle, is usually presented in the form of a hypnogram. The sleep cycle is regulated by specific areas of the cerebral cortex, as well as by the blue spot located in the brain stem.

What is slow wave sleep?

Slow sleep (also called orthodox sleep) has a duration of 80 to 90 minutes and occurs immediately after a person falls asleep. The formation and development of slow sleep is provided by the anterior sections of the hypothalamus, the nuclei of the suture, the nonspecific nuclei of the thalamus and the middle part of the pons (the so-called inhibitory center of Moruzzi). At the first stage of slow wave sleep, the alpha rhythm decreases, transforming into slow low-amplitude theta rhythms, equal in amplitude to the alpha rhythm or exceeding it. A person is in a state of drowsiness (half-sleep), dreamlike hallucinations are observed. Muscle activity decreases, the heart rate and respiration rate decreases, metabolic processes slow down, and the eyeballs move in slow motion. At this stage of sleep, solutions to tasks that seem to be insoluble during wakefulness are intuitively formed. At the very least, the illusion of their existence may arise. The first stage of slow wave sleep can also include hypnagogic twitching.

In the second stage of Non-REM sleep (this is usually light and shallow sleep), there is a further reduction in muscle activity, the heart rate slows down, body temperature drops, and the eyes become motionless. The second stage is about 55% of the total sleep time. The first episode of the second stage lasts approximately 20 minutes. The electroencephalogram at this point shows the predominant theta rhythms and the emerging sigma rhythms (the so-called “sleep spindles”), which are essentially accelerated alpha rhythms. At the moment the sigma rhythms appear, consciousness turns off. However, in the pauses between sigma rhythms, which occur with a frequency of 2 to 5 times in 1 minute, a person can be easily awakened.

At the third stage of slow wave sleep, the total number of delta rhythms is no more than 50%. At the fourth stage, this figure exceeds 50%. It is the fourth stage that is slow and deep sleep. Quite often, stages III and IV are combined, called delta sleep. It is extremely difficult to wake up a person during delta sleep. Dreams usually appear at this stage (up to 80%). A person can start talking, walking in a dream is not excluded, nightmares and enuresis may develop. At the same time, a person usually does not remember any of the above. The third stage lasts from 5 to 8% of the total sleep time, and the fourth takes from 10 to 15% of the total sleep period. The first four stages of slow wave sleep in a normal person last from 75 to 80% of the total duration of this physiological process. According to the researchers, Non-REM sleep provides a complete recovery of the energy expended during the day. In addition, the phase of slow wave sleep allows you to fix in the memory conscious memories of a declarative nature.

What is REM sleep?

REM sleep is also called REM sleep, REM sleep, or REM sleep. In addition, the generally accepted name is the REM stage (rapid eye movement). The REM stage lasts 10 to 15 minutes and follows slow sleep. REM sleep was discovered in 1953. The centers responsible for REM sleep are: the superior colliculus and the reticular formation of the midbrain, the blue spot, and the nuclei (vestibular) of the medulla oblongata. If you look at the electroencephalogram at this moment, you can see quite active fluctuations in electroactivity, the values of which are as close as possible to beta waves. During REM sleep, the electrical activity of the brain is almost identical to the state of wakefulness. However, at this stage, a person is completely motionless, since his muscle tone is at zero. At the same time, the eyeballs actively move under the closed eyelids, moving rapidly at regular intervals. If you wake up a person at the REM stage, then with a 90% probability he will talk about an exciting and vivid dream.

As noted above, the REM sleep electroencephalogram reflects the activation of brain activity and is more reminiscent of the EEG of the first stage of sleep. The 1st episode of the REM stage lasts from 5 to 10 minutes and occurs 70-90 minutes later from the moment the person fell asleep. During the entire period of sleep, the duration of the following episodes of REM sleep becomes more and more. The final episode of REM sleep can last up to 1 hour. The duration of REM sleep in a healthy adult is approximately 20-25% of the total sleep time. From one cycle to the next, the REM sleep phase becomes longer, and the depth of sleep, on the contrary, decreases. NREM sleep disturbances are not as difficult for the psyche as interruption of the REM phase. If some part of REM sleep is interrupted, then it must be replenished in one of the subsequent cycles. Experiments on mice have shown the deleterious effect of the absent REM phase on these mammals. After 40 days, the mouse deprived of REM sleep died, while the rodents deprived of REM sleep continued to live.

There is a hypothesis that during the REM phase, the human brain works to organize the information received during the day. Another theory is that REM sleep is especially important for newborns, providing nerve stimulation that promotes the formation and development of the nervous system.

Sleep duration

The duration of normal sleep can range from 6 to 8 hours a day. However, this does not exclude large deviations in one direction or another (4-10 hours). If sleep disorders are observed, then its duration can be equal to both several minutes and several days. When the duration of sleep is less than 5 hours, then this is considered a violation of its structure, which can lead to the development of insomnia. If you deprive a person of sleep, then after a few days his consciousness will lose the clarity of perception, there will be an irresistible urge to sleep, there will be “gaps” in the so-called borderline state between sleep and wakefulness.

Dreaming

Along with the corresponding physiological process, the word "sleep" also means a sequence of images that arise in the phase of REM sleep and, in some cases, are remembered by a person. A dream is formed in the mind of a sleeping person, being composed of a variety of subjectively perceived tactile, visual, auditory and other images. Usually a person who is dreaming is not aware that he is in a dream state. As a result, the dream is perceived by him as an objective reality. Lucid dreams are considered an interesting type of dreams, in which a person realizes that he is sleeping, and therefore can control the development of the plot in a dream. It is believed that dreams are inherent in the phase of REM sleep, which occurs with a frequency of once every 90-120 minutes. This phase is characterized by rapid movement of the eyeballs, rapid pulse and breathing, stimulation of the pons, as well as a short relaxation of skeletal muscles. In accordance with the results of the latest research carried out, dreams may also be inherent in the phase of slow wave sleep. At the same time, they are less emotional and not as long-lasting as REM-phase dreams.

Sleep pathologies

Sleep disorders of all kinds are quite common. For example, insomnia (insomnia) can be caused by psychosis, depression, neurosis, epilepsy, encephalitis, and other diseases. Apnea is a breathing disorder of a sleeping person, the causes of which can be mechanical or psychogenic. Parasomnias such as sleepwalking, nightmares, epilepsy and gnashing of teeth form and develop on the basis of neurosis. Pathologies such as lethargic sleep, narcolepsy and sleep paralysis are among the most severe sleep disorders. In case of any alarming factors associated with pronounced abnormalities in the structure of sleep, it is necessary to seek help from a specialist.

Hypnotic pharmacological agents

Sleep regulation using pharmacological agents should be carried out under the supervision of a physician. Along with this, it should be remembered that prolonged use of sleeping pills reduces the effectiveness of the latter. More recently, even drugs - morphine and opium - were included in the group of sedatives. For a long time, barbiturates were also used as sleeping pills. Melatonin is considered one of the most progressive drugs at the moment. An equally effective treatment for insomnia is the intake of magnesium preparations, which improve sleep and promote the production of the same melatonin.

Sleep study

According to prominent researchers of the past and present, sleep plays a more important role for the human body than food. In the second half of the 20th century, technologies for recording the activity of muscles (EMG), brain (EEG) and eyes (EOG) were developed, after which it was possible to form those ideas about the structure of sleep and its nature, which no one has yet refuted. ...

Deep sleep is a good night's rest. Human performance, emotional and physical condition depends on its quality. The rate of deep sleep for an adult is between ninety and one hundred and twenty minutes, taking into account several night cycles. The duration of a person's healthy sleep is eight to nine hours a day. It consists of four full periods: nap, shallow, slow and deep sleep. Drowsiness is characterized as a superficial condition lasting five minutes. At this stage, the body temperature becomes lower, the pulse and metabolism slow down, and breathing becomes quiet. During falling asleep, consciousness is switched off, but the reaction to external stimuli persists.

Deep sleep helps the body deal with stress and ailments. It helps to strengthen the immune system. Falling into deep sleep lasts for an hour, after which the fast phase begins.

A full night cycle in a healthy person consists of a slow and fast phase, and takes only about one hundred and twenty minutes. During the night, about four cycles are replaced, the duration of which depends on individual characteristics. The first cycle begins with deep sleep. In time, it lasts a long time, but gradually its duration decreases.

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

What are the stages of the slow phase? What is their feature?

Doze. 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 dormancy that the answers to seemingly insoluble problems are found.
Falling asleep. The slow phase continues. Consciousness gradually turns off, but the brain continues to respond. At this stage, it is easy to wake the person up even with a little noise.
Deep. Changes begin in the body, all processes and functions slow down, and the body relaxes completely.
Delta. It is difficult to wake up a person, since the body is completely relaxed, its temperature decreases, the respiration rate and blood circulation slow down.

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

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

REM sleep consists of four phases: nap, falling asleep, 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 are dreamed, including nightmares. The normal state is when the four stages of one cycle take up eighty percent of all sleep.

Deep sleep and slow sleep have their own characteristics:

in the slow phase, the body is physically healed, strength is restored, tissue and cell regeneration occurs;
people who sleep seven to eight hours a day recover their intellectual resources faster, their daily activities are much more efficient;
an increase in the duration of sleep helps to strengthen the immune system, and its decrease - to a decrease in the protective functions of the body;
if the slow phase lasts a small number of hours, the aging of the body is noticeably accelerated;
if the deep phase lasted a little, there are signs such as memory impairment, inability to concentrate on the subject of a conversation or a problem, decreased performance;
the slow phase, in contrast to the fast one, does not have compensatory properties, it is impossible to "sleep" it the next night.

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

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

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

The normal state of the body guarantees a well-built regimen of falling asleep and waking up. If you independently adjust the length of the rest at night, it will be much easier to wake up in the morning.
Sleep doctors advise against eating heavy food before going to bed. Smoking, energy drinks, caffeine all have a negative effect on sleep. A good snack would be a glass of kefir or milk, as well as an apple or any other fruit.
The deep phase will last longer if the body is given adequate physical activity about four hours before rest.
Walking in the fresh air, an active lifestyle, and intense physical exercise during the day contribute to rapid falling asleep and sound restful sleep. Light music, aromatherapy will improve your rest. Experts say that the quality of deep sleep is positively influenced by cricket singing.
It is important to ventilate the area well before bed. 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 establish the work of mental processes. Healthy, well-functioning sleep improves immunity, normalizes blood pressure, and reduces the risk of heart and vascular diseases, as well as mental disorders.

Deep sleep characteristics

During the night's rest, slow-wave and fast-wave periods alternate with each other. The cycle is formed by one period of slow and fast sleep. In total, from four to six cycles are replaced during the night, which last an hour and a half. For a child and an adult, it is normal if the deep period is thirty percent.

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

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 the morning rise will be easy. During deep sleep, connection with reality is lost, the body completely relaxes, which gives it the opportunity to recover.

During such a rest, some changes occur with 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 less frequent, blood pressure drops, the brain practically does not respond to external stimuli;
the gastrointestinal tract slows down its activity, therefore, sometimes upon awakening, you can feel mild nausea;
the cells of the body are restored at night, as growth hormone is actively produced;
the body spends 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 amount of oxygen, glucose, breathing quickens, the pulse rises. Women and men sometimes feel aroused, an erection occurs. Doctors advise sleeping at least seven hours a day. For children, pregnant women and patients with various diseases, this rate is higher.

How dangerous is the lack of adequate sleep? Almost everyone has experienced insomnia at least once. When you try to fall asleep, but fail, it causes irritation, the body loses more energy than during the day. Isolated cases of insomnia do not harm health, if it becomes systematic, problems arise. In this case, sleepy natural pills or sleeping pills are prescribed, depending on the duration of insomnia.

Sleep disturbance is a broad term that includes falling asleep problems, altered sleep patterns, and feeling unwell upon waking. They are all temporary, reversible disorders, but they manifest in the same way. A person feels fatigue, lethargy, apathy, mood decreases, there is no motivation to work.

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

Prolonged insomnia is provoked by chronic stress, overstrain, traumatic factors. Sometimes it becomes the cause and effect of a depressive state, as well as other mental disorders.
Diseases of the heart, blood vessels, central nervous system, malignant neoplasms play an important role in deep sleep disorders. Painful sensations, obsessive thoughts about illness, injury, osteochondrosis, frequent urge to urinate become grounds for insomnia.
Heavy physical activity, unfinished business and questions.
Poisoning, problems with the gastrointestinal tract.
High body temperature.

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

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