Every day the human body requires night rest. Human sleep has its own characteristics and is divided into slow-wave sleep and fast-moving sleep. What is best for the human body was determined by scientists who proved that both cycles are necessary for good rest.
Human sleep: its physiology
Daily sleep onset is a necessity. If a person is deprived of rest for three days, he becomes emotionally unstable, attention decreases, memory loss, and mental retardation occur. Psycho-neurotic overexcitation and depression predominate.
During sleep, all organs, along with the human brain, rest. At this time, people’s subconscious is switched off, and performance procedures, on the contrary, are launched.
To answer the question - slow sleep and fast sleep: which is better, you should first understand what is meant by these concepts
IN modern science the concept of sleep is interpreted as a periodic, functional period with specific behavior in the motor and autonomic spheres. At this time, immobility and disconnection from the sensory influence of the surrounding world occurs.
In this case, two phases alternate in a dream, with characteristic opposite characteristics. These stages are called slow and fast sleep.
Slow and fast cycle together restore mental and physical strength, activate the brain’s performance for information processing of the past day. In this case, the processed information is transferred from short-term memory to long-term memory.
This activity allows you to resolve problems accumulated during the day, as well as absorb the information that was received in the evening.
In addition, proper rest helps to improve the health of the body. When a person sleeps, he loses moisture, which is explained by slight weight loss. IN large quantities Collagen is produced, which is necessary to strengthen blood vessels and restore the elasticity of the skin.
That's why, To look good you need at least 8 hours of sleep. While a person sleeps, his body cleanses itself in preparation for the next day.
There is no clear answer to the question of whether slow or fast sleep is better - only ¾ of sleep time is spent on slow sleep, but this is enough for proper rest.
Slow sleep cycle, its features
Features of slow-wave sleep are:
- increase and decrease in pressure;
- preservation of average pulse rhythm;
- decline motor functions organs of vision;
- muscle relaxation.
During the slow phase, the body relaxes, breathing slows down, and the brain loses sensitivity to external stimuli, which is an indicator of a difficult awakening.
In this phase, cell restoration occurs due to the production of a hormone responsible for tissue growth and renewal of the muscular body. During the slow phase, recovery also occurs immune system, which indicates the importance of slow-wave sleep for the physiological state.
The main components of slow-wave sleep
slow sleep is divided into 4 phases with diverse bioelectrical characteristics. When a person falls into slow-wave sleep, the body's activity decreases, and at this time it is difficult to wake him up. In the deep stage of slow-wave sleep, heart rate and breathing increase, and blood pressure decreases.
Slow sleep rehabilitates and heals the body, restores cells and tissue, which improves the condition internal organs, REM sleep does not have such features.
Nap
When a person falls into a state of drowsiness, there is conjecture and revision of those ideas that appeared during daytime wakefulness. The brain is looking for solutions and possible correct ways out of current situations. Often people have dreams in which problems are solved with positive result.
Often during the phase of slow sleep - dozing we find a solution to a problem that exists in reality Sleepy spindles
After dozing, the sleep spindle rhythm begins. The disabled subconscious alternates with a threshold of significant hearing sensitivity.
Delta sleep
Delta sleep has it all character traits the previous stage, to which the delta oscillation of 2 Hz joins. The amplitude increase in the rhythm of oscillations becomes slower, and the transition to the fourth phase occurs.
Delta sleep is called the transitional stage to the deepest rest.
Deep delta sleep
This stage during slow-wave sleep is characterized by dreams, dull energy, and heavy lifting. A sleeping person is practically impossible to awaken.
The deep phase of delta sleep occurs 1.5 hours after going to bed. This is the final stage of slow-wave sleep.
Rapid sleep cycle, its features
Fast night sleep called paradoxical or fast wave. At this time there are changes in human body. REM sleep has its own distinctive features:
- clear memory of visible dream, which cannot be said about the slow-wave sleep phase;
- improved respiratory rate and arrhythmia of the cardiovascular system;
- loss of muscle tone;
- the muscle tissue of the neck and oral diaphragm stops moving;
- pronounced motor character of the apples of the visual organs under closed eyelids.
REM sleep with the onset of a new cycle has a longer duration, but at the same time, less depth, despite the fact that wakefulness approaches with each cycle, it is difficult to wake a person during REM sleep.
REM sleep has only two cycles: emotional; unemotional.
During the period of accelerated sleep, messages received the day before before rest are processed, data is exchanged between the subconscious and the mind. A quick night's rest is necessary for a person and the brain to adapt to changes in the surrounding space. Interruption of the sleep phase in question threatens mental disorders.
People who do not have proper rest are deprived of the possibility of rebirth protective functions mental health, as a result: lethargy, tearfulness, irritability, absent-mindedness.
Sequence of sleep stages
Slow sleep and REM sleep - which is better cannot be answered unequivocally, since both phases perform various functions. Slow cycle comes immediately, then comes deep rest. During REM sleep, it is difficult for a person to wake up. This occurs due to disabled sensory perceptions.
Night rest has a beginning - it is a slow phase. First, the person begins to doze, this lasts a little less than a quarter of an hour. Then stages 2, 3, 4 begin gradually, this takes about another 60 minutes.
With each stage, sleep deepens, and a fast phase begins, which is very short. After it there is a return to phase 2 of slow-wave sleep.
The change between fast and slow rest occurs up to 6 times throughout the night.
After completing the stages under consideration, the person awakens. Waking up occurs individually for everyone; the awakening process takes from 30 seconds to 3 minutes. During this time, clarity of consciousness is restored.
Scientific research has shown that a person who is frequently deprived of REM sleep can end up dying.
The reason why self-destruct occurs is unknown. Other studies show that in some cases, when there is a lack of the fast phase, treatment of depressive conditions is noted.
What is the difference between slow and fast sleep?
The body behaves differently during one or another phase of sleep; the main differences between the cycles are shown in the table.
| Distinctive characteristics | slow sleep | REM sleep |
| Eye movements | Initially, the motor process is smooth, freezing, and lasts until the end of the stage | There is a constant movement eyeballs |
| State of the vegetative system | During slow-wave sleep, there is a rapid, improved production of hormones produced by the pituitary gland | Suppression of spinal reflexes, manifestations of a rapid amplitude rhythm, increased heart rate. REM sleep is characterized by a vegetative storm |
| Dreams | NREM sleep is rarely accompanied by dreams, and if they do occur, they are calm character, no emotional plots | REM sleep is characterized by rich pictures, which is explained by vivid emotions, with a memorable color effect |
| Awakening | If you wake up a person during slow-wave sleep, he will have a depressed state, a feeling of fatigue of a person who has not rested, and waking up will be difficult. This is due to incomplete neurochemical processes of slow-wave sleep | During a quick night's rest, awakening is easy, the body is full of strength and energy, the person feels rested, well-slept, and the general state is cheerful |
| Breath | Infrequent, loud, shallow, with a gradual lack of rhythmicity occurring in delta sleep | Breathing is uneven, changeable (rapid or delayed), this is the body’s reaction to dreams that are seen in this phase |
| Brain temperature | Reduced | It rises due to the accelerated influx of plasma and the activity of metabolic processes. Often the brain temperature during sleep soon higher than during wakefulness |
Slow sleep and REM sleep, which cannot be better defined, because there is a chemical, physiological, functional dependence between them, in addition, they participate in a single balanced process of rest of the body.
During a slow night's rest are adjusted internal rhythms in the brain structure, a quick rest helps to establish harmony in these structures.
When is it better to wake up: in the NREM or REM stage of sleep?
The general state of health and well-being of a person depends on the phase of waking up. The worst time to wake up is deep dream. Having awakened at this moment, a person feels weak and tired.
The best time to wake up is the first or second stage after REM sleep ends. Doctors do not recommend getting up during REM sleep.
Be that as it may, when a person has had enough sleep, he is cheerful and full of energy. Usually this happens immediately after the dream, he reacts to sound, lighting, temperature regime. If he gets up immediately, then his condition will be excellent, and if he still pokes, it will begin new cycle slow sleep
Waking up during slow-wave sleep, which usually occurs when the alarm clock rings, a person will be irritated, lethargic, and sleep-deprived.
That's why The best moment of awakening is considered to be the one when a person did it on his own, no matter what time is on the clock, the body is rested and ready to work.
It is impossible to judge which sleep is better; slow sleep is needed to restart, reboot and rest the body. REM sleep is needed to restore protective functions. Therefore, it is better to have a full sleep, without lack of sleep.
Video in sleep phases, slow and fast sleep
What is sleep, as well as what is meant by the concepts of “slow sleep” and “rapid sleep”, which is better - you will learn about all this from the video below:
See tips on how to ensure yourself a full-fledged healthy sleep:
Before talking about the types of sleep, we should dwell on the electroencephalograms of physiological sleep.
Electroencephalography is a stage of great importance for the study of sleep and wakefulness. The first researcher to record electrical potentials in the brain was the mayor of Liverpool, Lord Richard Cato. In 1875, he discovered a difference in electrical potential between two points on the scalps of rabbits and monkeys. Domestic physiologists V.Ya. also contributed their talent to the development of this method. Danilevsky and V.V. Pravdich-Neminsky. It has already been noted that the first electroencephalographic studies on humans were carried out by the Jena psychiatrist Hans Berger, who discovered sharp differences between the biocurrents of the brain during sleep and wakefulness. It turned out that brain potentials during sleep are heterogeneous and subject to regular transformation.
In 1937-1938, English scientists Loomis, Horway, Habart, and Davis made the first attempt to systematize the obtained curves and described the five electroencephalographic stages of sleep. They did it so well that over the next 15 years only minor additions were made to the classification.
According to their classification, the first stage A characterized by the presence of a dominant resting rhythm - the alpha rhythm, corresponding to the state of “relaxed”, “passive” wakefulness. However, the alpha rhythm becomes uneven, its amplitude decreases, and periodically it disappears. Second stage IN- drowsiness, shallow sleep - characterized by a flattened picture of the electroencephalogram, the disappearance of the alpha rhythm and the appearance of irregular slow waves in the theta and delta ranges against this background. Third stage WITH- sleep of medium depth - characterized by “sleepy” spindles of waves of medium amplitude with a frequency of 12-18 per second. Fourth stage D- deep sleep - regular delta waves (two waves per second) of high amplitude (200-300 volts) appear, combined with “sleepy” spindles. Fifth stage E- greater deepening of sleep - rarer delta activity (one wave per second) and even greater amplitude (up to 600 volts).
Subsequently, attempts were made to improve this classification by increasing the stages and substages. L.P. Latash and A.M. Wayne, studying the stages of falling asleep in some groups of patients with pathological drowsiness, divided stage A into two substages, and stage B into four. Behind every picture of brain biopotentials there are real physiological mechanisms. Based EEG data determined that physiological sleep consists in a gradual transition from superficial to average depth sleep, but from medium to deep, after which everything gradually returns to the superficial stages and awakening. Sleep is going up and down stairs. The speed of this movement is different, and there are individual characteristics of the duration of stay on the steps going from wakefulness to sleep and from sleep to wakefulness.
Two types of sleep
Now let's return to the two types of sleep. It is believed that the first study that gave impetus to the discovery of two types of sleep was done in 1953 by Eugene Azerinsky, Kleitman's graduate student at the University of Chicago. He noticed periodically appearing rapid eye movements in children, accompanied by fast low-voltage rhythms on the electroencephalogram (desynchronization). Other scientists have established the same phenomena in adult subjects. Thus, during physiological sleep, periods of rapid eye movements (REM) are recorded 4-5 times per night. They first appear 60-90 minutes after falling asleep and then follow at the same intervals. The duration of the first REM period is short (6-10 minutes), gradually the periods lengthen, reaching 30 minutes or more by the morning. During these periods, the EEG pattern characteristic of wakefulness occurs after deep stages sleep (E) and by morning (against the background of stages D or C).
Thus, it was found that nighttime sleep consists of regular cycles, each of which includes stages B, C, D, E and the stage of desynchronization with REM. Consequently, we are already talking about repeated ascent and descent of the stairs.
Sleep cycles in people of different ages
What about children; B - young people; B - middle-aged people: 1- wakefulness; 2 - REM sleep; 3-6 - stages of slow-wave sleep
Based on the data obtained, the phase with desynchronization and REM sleep was called rapid, or desynchronized, sleep, since it contains fast rhythms. Thus, the entire dream was divided into slow sleep (stages A, B, C, D, E) and fast sleep. In adults, REM sleep takes up 15 to 25% of total sleep time. In ontogenesis, it appears early and dominates in the first period of life.
The table shows normal duration REM sleep at different ages, its share in sleep duration and in relation to the day as a whole. This indicator is very important because the duration of an individual's sleep can give an incorrect impression of the true duration of REM sleep.
REM sleep in humans
Clearly represented in ontogeny, REM sleep appears late in phylogeny. For the first time it can be found in birds - 0.1% of sleep; in mammals it occupies from 6 to 30% of sleep. Some summary data is presented in the table.
REM sleep in humans and various animal species
It is assumed that the duration of REM sleep is directly dependent on body size and life expectancy and inversely dependent on the intensity of the basal metabolic rate. Significant fluctuations in the ratio between slow and fast sleep in various types Some scientists explain animals by their peculiar relationship to two classes: “hunters”, who have a relatively high percentage of REM sleep, and those who are hunted (rabbits, ruminants), they have a relatively low percentage of this type of sleep. Perhaps the table data confirms the position that REM sleep is deep sleep; hunted animals cannot abuse it. Thus, in phylogeny, slow-wave sleep appears before fast sleep.A study of REM sleep has shown that although it can be defined as superficial based on its electroencephalographic pattern, it is more difficult to awaken a sleeper during this period than during slow-wave sleep. This gave the right to call it “paradoxical” or “deep”, in contrast to the already known “orthodox” or “light” sleep. We consider such a definition to be unsuccessful, since it can hardly be considered paradoxical dream, which is physiological in nature and naturally repeats four to five times every night.
During REM sleep, a person dreams. This was proven by waking up subjects in different stages of sleep. During slow-wave sleep, reports of dreams were rare (7-8%), while in fast sleep they were reported regularly (up to 90%). There is reason to designate REM sleep as sleep with dreams, and even, according to some authors, to believe that such a functional mental state brings this phase of sleep to life.
REM sleep is clearly represented in newborns and lower mammals. In opossums, it reaches 33% of the total sleep duration. In such cases it is hardly possible to talk about formed dreams. Most likely, REM sleep, due to its characteristics, is most favorable for the occurrence of dreams.
A characteristic feature of REM sleep is changes in the skeletal-motor system. Muscle tone decreases during sleep, and this is one of the first symptoms of sleep.
Three states of the nervous system
A - wakefulness; B - slow sleep; B - REM sleep: 1 - eye movement; 2 - electromyography; 3 - EEG of the sensorimotor cortex; 4 - EEG of the auditory cortex; 5 - EEG of the reticular formation; 6 - EEG of the hippocampus
Muscle tone relaxes especially strongly during REM sleep (primarily the facial muscles), muscle biopotentials decrease to the zero line. In humans and primates this shift is less pronounced than in other mammals. Special studies it was shown that changes in muscles are caused not by a decrease in descending facilitatory influences, but by an active strengthening of the reticulospinal descending inhibitory system.
Against the background of relaxed muscle tone, movements of various types occur. In animals - rapid movements of the eyes, whiskers, ears, tail, twitching of the paws, licking and sucking movements. In children - grimaces, convulsive twitching of the limbs. In adults, twitching of the limbs, sudden movements of the body, and finally, expressive movements appear, reflecting the nature of the dream being experienced.
The REM sleep phase is characterized by rapid eye movements. This served as the basis for another definition of REM sleep - REM sleep.
The differences between fast and slow sleep types are clearly revealed when analyzing shifts in the autonomic nervous system. If during periods of slow-wave sleep there is a decrease in breathing, heart rate, and a decrease in blood pressure, then in REM sleep a “vegetative storm” occurs: increased and irregular breathing is recorded, the pulse is irregular and frequent, arterial pressure rises. Such shifts can reach 50% of baseline. There is an assumption that the shifts are associated with the intensity of dreams and their emotional coloring. However, such an explanation is hardly sufficient, since such deviations occur in newborns and lower mammals, in which it is difficult to predict dreams.
During REM sleep, an increase in hormonal activity was also detected. These data indicate that REM sleep is completely special condition compared with slow-wave sleep and that the assessment of sleep as a homogeneous state is currently untenable.
Experimental studies have also shown that different brain formations take part in the implementation of slow and fast sleep. The French physiologist Michel Jouvet made a great contribution to elucidating the nature of REM sleep. He showed that REM sleep disappears with local destruction of the nuclei of the reticular formation located in the pons. This part of the brain is called rhombencephalon and hence another name for this stage of sleep is “rhombencephalic” sleep.
It is still extremely difficult to determine the place of REM sleep in the sleep-wake system. According to a number of indicators, this phase reflects a deeper sleep, in the implementation of which ancient brain apparatuses take part, which served as the basis for designating it as archaeo-sleep. By other measures, REM sleep seemed more shallow than slow-wave sleep. All this has led to the fact that some researchers even suggest identifying REM sleep as a special third state (wakefulness, slow-wave sleep, REM sleep).
The phases of human sleep are divided into two types - slow and fast. Their duration is uneven. After falling asleep, the slow phase lasts longer. Before waking up, REM sleep becomes longer.
In this case, the phases alternate, forming wave-like cycles. They last just over an hour and a half. Calculating the phases by the hour will not only make it easy to wake up in the morning and improve the quality of your night's rest, but will also help normalize the functioning of the entire body.
About sleep phases
Sleep is a state in which all organs, especially the brain, work in an unusual mode. At the same time, a person’s consciousness turns off and the restoration of all cells of the body begins. Thanks to a good, full night's rest, toxins are removed from the body, memory is strengthened and the psyche is unloaded.
In order to feel good during the day, your sleep rate should be about eight hours a day. However, this amount may vary depending on the individual characteristics of the human body.
For some, six hours is enough, for others, nine hours is not enough to fully relax and get enough sleep. This difference depends on the lifestyle and age of the person. Night rest is heterogeneous and is divided into two phases - REM and deep sleep.
Slow phase
NREM sleep is also called deep (orthodox) sleep. Immersion in it begins at the beginning of the night's rest. This phase is divided into several stages:
- Nap. Usually lasts from five to ten minutes. During this period, the brain is still working, so you can dream. Often there are dreams that are confused with reality, and a person may even find answers to problems that were unresolved during the day.
- Falling asleep or sleep spindles. Takes approximately twenty minutes. At this stage, consciousness gradually turns off, but the brain reacts quite sensitively to all stimuli. At such a moment, any noise can wake you up.
- Deep dream. This is the time when the body healthy person almost ceases to function, and the body relaxes. However, weak impulses still pass through the brain, and sleep spindles are still preserved.
Then comes delta sleep - this is the deepest period. The body relaxes completely and the brain does not react to stimuli. Respiration rate and blood circulation decrease. But the closer to morning, the more the duration of the delta sleep phase decreases.
Interesting ! When falling asleep and waking up, a condition such as sleep paralysis. This condition is characterized by full understanding of what is happening, but the inability to move or say anything. Some people try on purpose.
Fast phase (REM phase)
REM sleep after falling asleep lasts about five minutes. However, with each new cycle, the duration of deep sleep becomes shorter, and the duration of fast sleep increases in time. This phase is already about an hour in the morning. It is during this time period that a person is “easy” to get out of bed.
Fast phase divided into emotional and non-emotional periods. In the first period of time, dreams become pronounced and dynamic.
Phase sequence
The sequence of sleep stages is the same for most adults. This statement is valid for healthy people. REM sleep passes quickly after falling asleep. This phase follows four stages deep sleep. Then follows one turn, which is designated as 4+1. At this time, the brain works intensively, the eyes dart around, and the body is “tuned” to wake up. The phases alternate; there can be up to six of them during the night.
However, age or problems associated with sleep disturbances may change the picture. For example, in young children, more than 50% is the REM phase. Only at the age of 5 years the sequence and duration of the stages become the same as in adults.
In old age, the REM sleep phase is reduced, and delta sleep may disappear altogether. This is how age-related insomnia manifests itself. Some people have head injuries or don't sleep at all. Often they are just dozing. Some people wake up many times during the night, and in the morning they think that they haven’t slept at all. The reasons for this manifestation may be different.
In people with narcolepsy or sleep apnea, nighttime rest is atypical. They get it right away fast stage, they fall asleep in any position and place. Apnea is a sudden stop in breathing during sleep, which is restored after a short period of time.
At the same time, due to a decrease in the amount of oxygen, hormones are released into the blood, which causes the sleeping person to wake up. These attacks can be repeated many times, rest becomes short. Because of this, a person also does not get enough sleep; he is haunted by a sleepy state.
The value of a night's rest by the hour
A person can get enough sleep in one hour or throughout the night. The value of rest depends on the time you go to bed. The following table indicates sleep efficiency:
| Time | Value |
| From 19:00 to 20:00 | 7 o'clock |
| From 20:00 to 21:00 | 6 hours |
| From 21:00 to 22:00 | 5 o'clock |
| From 22:00 to 23:00 | 4 hours |
| From 23:00 to 00:00 | 3 hours |
| From 00:00 to 01:00 | 2 hours |
| From 01:00 to 02:00 | 1 hour |
| From 02:00 to 03:00 | 30 minutes |
| From 03:00 to 04:00 | 15 minutes |
| From 04:00 to 05:00 | 7 minutes |
| From 05:00 to 06:00 | 1 minute |
Previously, people went to bed and got up only according to the sun. At the same time, we got a full night's sleep. IN modern world Few people get ready for bed before midnight, which is why fatigue, neuroses and hypertension appear. Lack of sleep is a frequent companion in our lives.
Required duration of rest by age
To rest, a person needs different time, and it depends on age. This data is summarized in the table:
Elderly people often experience certain ailments. Because of them and physical inactivity, they often sleep only five hours. At the same time, in the womb of the mother, the unborn child remains in a state of rest for 17 hours.
How to determine the optimal time to wake up and why calculate sleep phases
Exist special devices that record brain activity. However, in their absence, you can calculate the phase times yourself. NREM sleep takes much longer than REM sleep. If you know how long all the stages are, you can calculate at what stage the brain will work in the morning when a person wakes up.
It is very important to get up during the REM stage of sleep, when we are light sleepers. Then the day will pass joyfully and cheerfully. This explanation is the answer to the question in which phase of sleep a person should wake up.
You can determine this stage yourself only by experiment. You need to approximately calculate the time of REM sleep. Wake up at this time and understand whether it was easy to open your eyes and get up. If yes, then in the future try to wake up at this time. This way you can determine how long a particular person should rest at night.
Important! When conducting the experiment, you should not forget about the time of going to bed. It is of no small importance.
There is a special calculator that determines the online phases of a person’s sleep by time. It is capable of calculating all stages using algorithms. This calculator is quite easy to use. You just need to indicate the hour when the person goes to bed. The program will perform a calculation and show the result at what time people will wake up well rested, that is, how many hours are needed for rest.
Rules for a healthy night's rest
There are several effective rules that will ensure a strong healthy holiday at night and will allow you to achieve high performance and wellness. They are also the answer to a frequently asked question about how to improve sleep quality:
- It is advisable to stick to a routine, always fall asleep and get up at the same time.
- Sleep should always take place between 00:00 and 05:00. It is during this period that the most melatonin, the sleep hormone, is produced.
- You cannot have dinner later than three hours before your night's rest. If you want to eat during the specified interval, it is better to drink a little milk.
- Evening walk on fresh air It will not only help you fall asleep faster, but also make your rest complete.
- Before going to bed, you can take a bath with herbs (chamomile, lemon balm or motherwort). It will help you calm down and fall asleep faster.
- It is necessary to ventilate the room before going to bed.
- The recommended sleeping position is on your back or right side; it is not advisable to sleep on your stomach.
By following these recommendations, your sleep quality improves. You also need to do exercises every morning. Run - the best remedy for a cheerful day. However, there is no need to engage in charging “through I can’t.” This leads to overvoltage. It is better then to go in for sports in the afternoon or evening.
Many people have heard that sleep consists of sequentially replacing each other. phases and stages. Some people know that in some phases it is easier to wake up, in others it is harder, so ideally, awakening should be adjusted to certain stages of sleep. Someone will say that dreams occur only in one phase (small spoiler - in fact this is not so, see below). In this article we propose to delve deeper into these and other issues related to different periods sleep, and consider what phases stand out, what is their characteristic And duration, how many phases are needed in order to get enough sleep, and how to independently calculate sleep phases. In addition, in the last part of the text we will look at how some so-called rational sleep patterns are assessed in terms of phases and stages.
Phases of human sleep: preface
Dreams seem like such an ordinary thing, and yet it is one of those areas that still holds many mysteries. In particular, so far there is no consensus among scientists even regarding whether we see But stages and phases of human sleep can be considered fully studied, including because they are easier to study using various instruments. The main sources are colored dreams or black and white. data for scientists - the activity of the brain in general and its lobes in particular (shown on the electroencephalogram - EEG), movements of the eyeballs and muscles of the back of the head. These and a number of other indicators make it possible to draw a more or less clear picture of sleep phase cycles.
In general, we propose not to delve into the terms and methods of somnology (the science of sleep), but to consider the phases of sleep on a more practical level: understand how many phases are distinguished, analyze their main features and what distinguishes the phases from each other. This knowledge will help answer questions about which phase is easier to wake up in, how long a healthy sleep should last, etc. But first let's do a few remarks:
- phases and stages are discussed with examples adults(with age, the ratio and duration of the phases changes);
- For simplicity and consistency, sleep periods will be shown using examples from those who goes to bed in the evening or at the beginning of the night, and not in the morning and does not work at night;
- we only consider physiological sleep– medicinal, hypnotic, etc. are not taken into account in this material;
- we will focus on those who are lucky enough to sleep a sufficient number of hours for your body and is not forced, for example, to run to the first class after writing a coursework all night.
So what should it be normal sleep in the average healthy person under similar conditions?
In general, experts divide sleep into two phases:
- slow sleep, aka orthodox, or NREM sleep. The name NREM comes from the English Not Rapid Eye Movement and reflects the fact that this phase is not characterized by rapid eye movements.
- REM sleep, aka paradoxical, or REM sleep(i.e. rapid eye movements are present). The name “paradoxical” comes from the fact that during this phase of sleep, complete muscle relaxation and high brain activity are combined. It turns out that during this period the brain works almost the same as when awake, but it does not process information received from the senses and does not give orders to the body how to react to this information.
The NREM + REM sleep cycle lasts approximately 1.5-2 hours(more details below), and during the night these phases successively replace each other. Average 3/4 cycle falls on slow-wave sleep and, accordingly, about a quarter– to fast.
At the same time, slow-wave sleep has a number of stages:
- nap– transition from wakefulness to sleep;
- light sleep ;
- moderately deep sleep;
- deep dream- It is at this stage that sleep is the deepest.
Stages 3 and 4 are collectively called - delta sleep, which is associated with the presence of specific delta waves on the EEG.
Diagram of the night cycle by phases and stages of sleep
In terms of sleep cycles, our night goes like this:
- First comes stage 1 slow-wave sleep, that is, we move from wakefulness to sleep through drowsiness.
- Next we sequentially go through stages 2, 3 and 4. Then we move to reverse order– from delta sleep to light sleep (4 – 3 – 2).
- After stage 2 comes phase REM sleep. Due to the fact that it is the last to be activated in the cycle - after all other stages have passed - it is sometimes called phase 5 or stage 5, which, strictly speaking, is not entirely accurate, because REM sleep is completely different compared to slow wave sleep .
- Then we go back to stage 2, and then we again plunge into delta sleep, then light, then fast, then light again... And so the change of phases and stages goes in a circle. Another option is that after REM sleep, awakening occurs.
Duration of sleep phases and stages
As we said above, the entire sleep cycle (slow and fast sleep) takes on average about 1.5 hours to 2 hours. At the same time, the duration of phases and stages and their ratio within one cycle changes over the course of the night. Let's look at how the phases are distributed on average and how long each of them lasts.
Thus, in the first cycle, full-fledged deep sleep (stage 4) occurs approximately 40-50 minutes after sleep, and fast – In 1.5 hours. Based on the average need for sleep, we find that in a normal state a person needs to sleep 3-6 cycles per night - depending on their duration and his need for sleep. In turn, this need varies greatly: some need 4 hours, for some the norm may exceed 10 hours.
In what phase is it better to wake up and how to calculate it
As is known, It's easiest to wake up during REM sleep, in second place is the lung stage. Knowing the sequence different periods, you can guess optimal time awakening. On the other hand, it must be taken into account that the duration of the phases is not the same different people In addition, the need for one or another “type” of sleep varies depending on the condition. For example, if you are tired, sick, or recovering from an illness, slow-wave sleep may take longer.
Of course, to make it easier for you to wake up, you can buy various gadgets that read characteristics phases (more details below) and wake up 
you exactly at the right time. But you can find out how to wake up during REM sleep on your own - First of all, you need to experiment. For example, take 2 hours as a sleep phase, calculate what time you need to go to bed/wake up in order to withstand a whole number of cycles. For example, if you have to get up at 8 am, the multiples of the phases would be 6 am, 4 am, 2 am, midnight, etc. When calculating the time, take into account the fact that you will need a little more time to fall asleep. As we said, Stage 1 usually takes 5-15 minutes. That is, to get up at 8, you need to go to bed at 1:45 or 23:45.
Try following this schedule for a while and see if you are able to wake up during REM sleep. If not, “play” with the boundaries - make a calculation based on 1 hour 50 minutes or 1 hour 40 minutes. This way you can find exactly your duration of the night cycle and then build on it. It is best to conduct experiments when you are in normal physical and emotional state and slept more or less normally on the eve of the experiments.
We also hint that by “go to bed” we mean exactly go to bed, and not “lie in bed with a smartphone in your arms and chat in instant messengers for another hour.” Let us also note that calculating sleep phases will not give you vigor if you have been sleeping only one cycle per night for a week. Adjusting to the phases is a tool for waking up easier, but it will not free you from the need to fully sleep.
Phases of sleep and dreams
What happens to us in different stages of sleep
One of the main differences between the phases is different brain activity, which can be visually traced in the waves on the EEG, but the physiology of the sleep phases is characterized not only by this. Another difference between fast and slow is reflected in English names REM and NREM – the presence and absence of rapid eye movements. In general, determining the sleep phase by eye, without taking into account instruments and measuring various indicators, is quite problematic. We can only say that if a person moves his eyes, limbs, etc., most likely we are talking about REM sleep. What can be registered on various devices? Here are some interesting facts.
Traits of slow-wave sleep
To plunge into the first stage of slow-wave sleep (drowsiness), the brain produces special substances that block its activity, cause lethargy, and also affect other body systems, including slow down metabolism. In stages 2-4, especially during delta sleep, metabolism also slows down.
To say that during slow-wave sleep, in principle, no eye movements, not entirely true - they are in stages 1 (drowsiness) and 
2 (light sleep), but specifically slow; in English terminology they are called slow rolling eye movement (SREM). In turn, during delta sleep there are not even such movements, but it is in this phase that people walk or talk in their sleep, and also perform other uncontrolled actions, if this is typical for them.
Traits of REM sleep
One of the main features of REM sleep is the most vivid dreams. By the words “the most vivid” we mean that almost all the dreams that we remember after waking up are from this phase. It is believed that REM sleep, in turn, is responsible for processing information received during the day, internal work on emotions, etc. But so far scientists cannot say exactly how exactly what happens during REM sleep and what mechanisms are involved.
As we have already noted, visual REM sleep can be recognized by the movements of the eyeballs, sometimes ragged breathing, hand movements, etc. This phase is also characterized by changes in body temperature and heart rate: they can increase or decrease within the same stage.
I wonder what brain activity during REM sleep is so high that scientists for a long time could not notice the difference on the EEG between this phase of sleep and wakefulness. True, to date several important differences have been found.
Interesting features associated with sleep phases
It is typical for any phase distorted view of time. Probably everyone is familiar with situations when you close your eyes for a minute and 5 hours are gone. The opposite is also true: it seemed like the whole night had passed and I had a lot of dreams, but in fact only 20 minutes had passed.
Some people believe that during sleep a person is completely disconnects from reality, however, in reality this is not the case. Many signals are indeed not processed properly by the brain, especially during 
delta sleep, but during REM and lung main sounds become a source of information. For example, we are not always awakened by noise, but a person can wake up from the fact that someone even quietly calls his name. Also, during REM sleep, sounds can be integrated into the dream and become part of it. This suggests that the brain processes sounds during sleep and decides what to pay attention to and how exactly to do it.
In children, the proportion of REM sleep is greater than in adults, and in older people it is even less. That is the older we get, the shorter the paradoxical phase sleep and longer orthodox. Interestingly, REM sleep is observed even in children in the womb. Scientists say that in the early stages of life (including before birth), REM sleep is very important for the formation of the central nervous system.
Research shows that the brain may not be immersed entirely in the same phase, which is especially characteristic of delta sleep. Although most of the brain is usually at the same stage.
The importance of sleep phases for the body: a small warning
It is impossible to say which sleep is better or more useful - fast or slow. Both phases are needed for proper rest and recovery. the body both at the physiological and mental levels. In this regard, questions arise about sleep patterns in which there is no full cycle. Surely many have heard about schemes that suggest that a person sleeps not once a day for 6-8 hours, but several times during the day. 
Some of these schemes seem quite harmless, but the benefits of others are seriously questionable.
In particular, there is information on the Internet about a supposedly very effective schedule when you need to sleep 6 times for 20 minutes or 4 times for 30 minutes. Based on a typical sleep cycle, these time periods are very short, and in 20-30 minutes a person will not have time to move beyond stages 2-3, that is, we are not talking about deep and REM sleep in principle. Meanwhile, the most important processes for our body occur precisely at these stages. It is possible that people who are described as having success with such regimens have very compressed sleep cycles, but there is a good chance that the reality is simply embellished for the sake of an impressive story.
Of course, for some time the average person’s body will function on 20 minutes 6 times a day. It may even seem to him that he has begun to spend time more efficiently, but the benefits of these schemes for the body are in this case raises questions. Systemic lack of sleep affects both the mental and physical condition and leads to various unpleasant consequences. Without denying the benefits and effectiveness of other rational sleep patterns, we urge you to consult your doctor and be very wary of options that do not include at least several full cycles per day.
Adequate rest is one of the main components of human health. For the formation, development, normal functioning The body creates ideal conditions during sleep. Only during this period are beneficial hormones produced and amino acids are synthesized. There is also improvement, systematization of brain activity, and unloading of the nervous system.
To understand the processes taking place, you should study what slow and fast sleep is, what are the differences between these structural units and determine their importance for people. It is good to compare these parameters using indications from comparative tables.
Psychophysical processes occurring during sleep divide it into phases. At this time, different activity of the brain is observed, regeneration of certain organs and systems occurs.
REM sleep and slow-wave sleep have a certain relationship with each other. It changes with the transition from one cycle to the next. Constant interruption of one of the components has negative consequences.
Phase components of sleep and their order
Sleep is a definite structure; it includes several cycles that appear 4-5 times during the night. Each one is approximately 1.5 hours long. This form contains phases of slow and fast sleep.
An adult's rest begins with napping, which is the initial structural unit slow period. Next, three more components pass in turn. Then there comes a short period. The duration changes every cycle.
Features of slow sleep
The slow period lasts three-quarters of the entire rest period. After falling asleep, it is at its greatest length, gradually shortening in the morning.
During a long rest, 4-5 periods are included in the cycles; this is the optimal value. It begins the process of putting a person to sleep. At the third phase stage, attacks of sleepwalking may occur.
Structure
This phase is structured by periods. They all play great importance for a person. Each has its own characteristics, features, and functions change in the process.
- nap;
- sleep spindles;
- delta sleep;
- deep delta sleep.
The first period is characterized by slow eye movement, a decrease in temperature occurs, the pulse becomes less frequent, and nervous activity stabilizes. It is at this moment that a solution to a problem that appeared during the day can come, the missing link in the semantic chain can be filled. Waking up is very easy.
In the second period, consciousness begins to switch off, the person sinks deeper into slumber. The pulse is rare, muscle relaxation occurs.
During the third stage, the heart begins to contract more frequently and more shallow respiratory oscillations occur. The flow of blood to the tissues is activated, eye movement occurs very slowly.
The last period is characterized by the greatest immersion. At such a moment, it is very difficult for people to wake up, they get up unrested, have difficulty integrating into the environment, dreams are not stored in memory. All body functions are significantly slowed down.
Signs
You can understand that a person is in the slow-wave sleep phase by comparing characteristic indicators: breathing, which becomes rare, shallow, often arrhythmic, the movement of the eyeballs first slows down, then completely disappears.
The heart rate slows down and the body temperature becomes lower. By this period, the muscles relax, the limbs do not move, physical activity absent.
Meaning
While in slow-wave sleep, internal organs are restored. During this time, growth hormone is released, this is especially important for children. They develop and improve all their systems over such a period.
It is important to know! During this period, substances necessary for the normal functioning of the body accumulate and amino acids are synthesized. This type of sleep is responsible for physiological rest.
Contradictions of paradoxical sleep
REM sleep is also called paradoxical because of its inconsistencies various manifestations internal processes. During this period of rest brain activity very active, it can be even higher than when awake, but at this time the person is in the process of dozing.
Muscle tone is significantly reduced, but the stage is characterized by movement of the eyeballs and twitching of the limbs. If such a rest for some reason takes a long time, upon awakening there is a feeling of exhaustion, snippets of dreams are spinning in the head.
Manifestations
The fact that a person is in the REM sleep phase can be noticed without the help of devices. There are a number of specific manifestations. These include:
Body temperature rises and heart rate increases. The brain begins to be active. During this period of rest, unification, comparison occurs genetic information with the purchased one.
The value of the fast phase
In between quick rest the nervous system is activated. All acquired knowledge, information, relationships, and actions are processed and analyzed. Serotonin, the hormone of happiness, is produced.
During this period, the formation of the most important mental functions in children. Insufficient duration of such rest may mean the rapid appearance of problems with consciousness. Programs for future human behavior are created, answers to questions that cannot be found while awake are formulated.
Dreams
The dreams that come to a person during this phase are the most vivid and memorable. They are emotionally colored and dynamic. External stimuli can be intricately woven into the plot of a vision.
Visions are transformed into different symbols, images, and everyday reality. In the paradoxical phase, a person usually realizes that events are not happening in reality.
Awakening in different phases: differences
The structure of sleep is heterogeneous. All phases are distinguished by different brain activity, psychophysical activity, and regeneration of certain human systems.
It is important to know! The incompleteness of the processes causes a difficult transition to wakefulness in slow-wave sleep. When climbing quickly, the climb is easy, and the start of vigorous activity occurs without problems. But constant interruption of rest in this phase has a negative effect on the psyche.
Table: comparative characteristics of sleep phases
Parameters characterizing rapid and slow-wave sleep are shown comparison table. This is the basic data that helps to recognize the rest period. From one cycle to the next, the duration of the first becomes shorter, while the paradoxical one lengthens.
| Indicators | Slow phase | Fast phase |
|---|---|---|
| Number of stages | 4 | 1 |
| Sleep depth | deep | surface |
| Having dreams | calm, poorly remembered | vivid, emotional, retained in memory |
| Eye movement | no or very slow | fast |
| Muscle tone | slightly reduced | sharply weakened |
| Breath | rare, stable | arrhythmic |
| Heartbeat | slowed down | accelerated |
| Body temperature | reduced | increased |
| Duration | 75-80% rest | 20-25% of sleep duration |
Sleep Research: Interesting Facts
The paradox of time perception is often encountered in relation to sleep. There are times when it seems like you just closed your eyes, and several hours have already passed. The opposite also happens: it seems that you slept all night, but 30 minutes have passed.
It has been proven that the brain analyzes sounds, sorts them, and can weave them into a dream. Moreover, in some phases people can awaken if they are called by name in a whisper. The greater the biological age of a person, the shorter the duration of the paradoxical stage. In infants it exceeds the slow one.
A person spends a third of his life sleeping. If you sleep less than a quarter of a day for two weeks, the state of the body will correspond to being in drunkenness. Memory will deteriorate, concentration and reaction will suffer, and problems with coordination will arise. But many geniuses practiced polyphasic rest over a long period of time, the total duration of which was no more than half the norm. At the same time, they felt cheerful, their performance improved, and discoveries were made.
Absolutely all people see dreams, but almost all of them are forgotten. Animals also dream. Not so long ago most of humanity saw black and white dreams, and now 85% of men and women view vivid stories. The explanation for this is the creation of color television broadcasting.
Blind people are also not deprived of dreams. If the blindness is acquired, then the pictures represent what was previously seen. In congenital blindness, vision consists of sounds, smells, and sensations. They do not experience the phenomenon of rapidly moving eyes under their eyelids. These people are much more likely to have nightmares.
The longest period of wakefulness of a healthy person was the period of 11 days during which an American schoolboy did not sleep. After a head injury and brain damage, a Hungarian soldier did not take a nap for 40 years. At the same time, he felt cheerful, did not experience fatigue or discomfort.
It is important to know! Few girls dream of slim figure, know the following fact. Systematic lack of sleep leads to weight gain excess weight. One of important conditions Losing weight is getting enough sleep.
Women's deep rest is often 20 minutes longer than men's, but the latter sleep more restlessly and wake up more often. The weaker sex complains more about sleep disturbances and gets less sleep. Ladies are more susceptible to emotionally strong visions and nightmares.
Conclusion
You can’t make a choice about whether fast or slow sleep is better. Both of these components must be present in a person’s rest without fail and in the correct percentage.
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