The whole dream is divided into two fundamentally different types - this slow sleep and REM sleep. In turn, slow-wave sleep is divided into 4 phases. It turns out that there are only 5 different phases of sleep.
slow sleep
It is also called the dormancy stage. It is characterized by thinking and experiencing problems that arise during the day. The brain, by inertia, tries to find a solution to the problems it was working on while awake. A person can see images that implement a solution to a problem.
There is a further decrease in muscle activity, pulse and breathing slow down. The brain gradually stops working. This stage is characterized by short bursts of auditory sensitivity. Several times a minute a person is in a state where it is very easy to wake him up.
Is transitional. The difference between stages three and four of sleep is the number of delta oscillations. But we will not delve into such details.
Characterized by the deepest sleep. It is considered the most important, since at this time the brain receives the most complete rest and restores its performance. In the fourth stage of sleep, it is difficult to wake a person. Cases of talking in a dream or sleepwalking occur precisely in this phase.
The first two phases are considered shallow slow-wave sleep, and the second two are considered deep sleep. NREM sleep is also called orthodox sleep or non-REM sleep.
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REM sleep(REM sleep)
This stage is also called REM sleep (from the English rapid eye movements, which means “rapid eye movements”). As you may have guessed, REM sleep is characterized by rapid movements. eyeballs under closed eyelids - this is the first fundamental difference from slow-wave sleep.
The second difference is that in the REM sleep phase the brain does not rest at all, but on the contrary, it is activated. The heart rate also increases, but the large muscles are completely relaxed.
And the most interesting thing is that in the REM sleep phase it is most difficult to wake a person, although his state is closest to the state of wakefulness. That's why REM sleep is also called paradoxical sleep.
The purpose of REM sleep is not entirely clear. There are several assumptions about this:
1. During the REM sleep stage, the brain sorts out the information received.
2. The brain analyzes the environmental conditions in which the organism is located and develops an adaptation strategy. Indirect confirmation of this judgment is the fact that in newborns REM sleep is 50%, in adults - 20-25%, in older people - 15%.
But there is one fact that does not cause controversy - the most vivid dreams come to us in REM sleep! In other stages, dreams are also present, but they are blurred and we remember them very poorly. Scientists also say that you will only remember a dream well if you wake up in the REM phase.
Sequence of sleep stages
Sleep begins with phase 1, which lasts approximately 10 minutes. Then the 2nd, 3rd, and 4th phases follow sequentially. Then in reverse order- 3rd, 2nd and the REM sleep phase begins. Together they form a cycle that repeats 4-5 times a night.
This changes the duration different phases from cycle to cycle. In the first cycle, REM sleep is very short, longer time occupies deep slow-wave sleep. But in the last cycles there may be no deep sleep at all. Typically one cycle is 90-100 minutes.
Now comes the fun part. Your well-being depends on what phase of sleep you wake up in. The worst thing to wake up is deep dream. When you wake up from a deep sleep, you will feel groggy.
It is best to wake up after the end of the REM sleep phase, that is, at the beginning of the first or second phase. Waking up from REM sleep is not recommended.
Now you probably have a question about how to make sure you wake up in the right phase.
I will express only one thought on this matter. As already mentioned, it is quite difficult to wake a person in the deep sleep stage. Therefore, if your sleep is interrupted naturally, and not by an alarm, then you are more likely to wake up in the right phase.
Now a little about the importance of fast and slow sleep. Some scientists say that REM sleep is a relic of the past, supposedly a person does not need it, just like the appendix.
The following facts are cited in support of this statement:
If you forcibly limit the duration of sleep, then the duration of the deep phase of sleep practically does not change; the brain primarily reduces the duration of REM sleep.
But this only proves that deep sleep is more important than fast sleep - no more!
Experiments have been conducted where people were completely deprived of REM sleep for two weeks. However, their health did not deteriorate in any way.
Two weeks is not that long, considering that some people can live that long without sleep at all.
But other scientists conducted experiments on rats. As a result, after 40 days without REM sleep, the rats died.
The sleep process is a very little studied phenomenon. In the future, sleep scientists will have to find answers to many controversial questions.
Well, we need to take care of our sleep and lead a healthy lifestyle!
Duration and quality of sleep– criteria that influence many factors: mood, well-being, feeling of cheerfulness. In preparation for a new day, we try to go to bed early, but in the morning we wake up exhausted and lethargic. On another day, on the contrary, after a short sleep, we wake up on our own, feeling cheerful and strong. Why does this happen and how to learn to get enough sleep? To answer these questions, we will analyze the phases of human REM and NREM sleep in time and their characteristics.
Discoveries of scientists
Today, sleep is an understandable physiological state. But it was not always so. For a long time scientists could not track what changes occur in a person during rest. The topic was closed and difficult to study. In the 19th century, they assessed a person’s posture, measured blood pressure and temperature, and took other indicators. For detailed study, sleepers were awakened and changes were recorded.
Hand turns off alarm clock early in the morning
Early attempts at sleep intervention have yielded results. Scientists have found that sleep goes through stages of varying duration rapid and deep sleep of a person, and their importance is great, since it affects all indicators of the body. The German physiologist Köllschutter found that deep sleep occurs in the first hours of rest, and then it turns into superficial sleep.
After the discovery of electric waves, scientists took a complete picture of what was happening to the sleeper. An electroencephalogram helped to understand what was happening to a person during rest. In this case, the subject did not have to be woken up. Thanks to new technologies, it has become known that sleep goes through 2 phases: slow and fast sleep.
Stages of slow-wave sleep
Orthodox sleep is divided into stages. The stages differ in the duration and depth of rest. Let's look at the stages of slow-wave sleep:
First. Occurs after a person closes his eyes. The first stage is called napping. A person is not yet falling asleep; the brain is in an active stage. Within 10–15 minutes. the vacationer processes information that happened during the day. During this period, solutions are found to the questions that tormented a person.
Second. At this stage, “sleep spindles” appear. They occur at intervals of 3–5 minutes. During their passage, consciousness is completely switched off. In between sleep spindles, a person is sensitive to what is happening around him. He hears voices or sounds. This feature allows the mother to hear the baby’s cry at night. If you call a sleeping person by name, he will immediately wake up. Physiological changes boil down to a decrease in muscle activity and a slower heart rate.
During the second slow phase of sleep, a person hears sounds
Third. Stage of delta sleep or transitional. “Sleep spindles” are preserved and become longer lasting. Delta oscillations are added to them. The third stage is called preparatory stage before deep sleep.
Fourth. At this stage, the pulse quickens and blood pressure rises. The person falls into deep sleep. Dreams during this period are unclear and blurry. If the vacationer wakes up during the fourth stage, he will not remember what he dreamed.
People who sleepwalk or talk in their sleep do not remember anything the next morning. This is due to the fact that all events occur in the deep stage of sleep. Even if you interrupt the sleepwalker, he will not understand why he is not in bed and how he ended up in another room. It is at this stage that people have nightmares.
Duration of deep sleep directly depends on the age of the person and the physical condition of his body. For example, the duration of a child's deep sleep phase is 20 minutes, but the quality of sleep is completely different than that of most adults: it is much stronger, children may not respond to external stimuli (sound, light, touch). Thus, even the smallest ones restore energy, “reboot” the body’s systems, and charge the immune system.
How long does the deep sleep phase last? The deep sleep phase, the duration of which varies depending on the specific stage, generally lasts one and a half to two hours. Of these, 5-10 minutes are “allocated” for napping, 20 minutes for the second stage (slowing breathing and heart rate), and 30-45 minutes for the third and fourth phases.
The girl sleeps sweetly, hugging a pillow
Features of REM sleep
After deep sleep ends, REM sleep begins. The fifth stage was discovered by Kleitman in 1955. The recorded indicators made it clear that the indicators of the body during REM sleep in humans are similar to the state of wakefulness. The REM sleep phase is accompanied by:
constant movement of the eyeballs;
significant decrease in muscle tone;
emotionally charged and action-packed dreams;
complete immobility of a person.
How long does REM sleep last? In total, shallow sleep makes up 20-25% of the average night's rest time, i.e. one and a half to two hours. One such phase lasts only 10-20 minutes. The most vivid and memorable dreams come during the REM sleep stage. If a person is awakened during this period, he will fully tell what he dreamed.
Baby is sleeping
Why are sleep phases needed?
A person’s well-being is inextricably linked with rest and sleep. No wonder. In the first months of life, a little person has a strong connection with nature and obeys its laws. As adults, we make decisions about how much sleep we need. Often untrue, so the mental is disturbed, emotional condition person - that is why it is important to know the frequency of fast and deep stages in night sleep and be able to calculate the stages of sleep for the time of awakening.
Scientists calculated sleep phases and after a series of studies came to the conclusion that 4–5 cycles pass per night. During this period, the person is restored. During slow-wave sleep, energy expended during the day is replenished. REM sleep is short in the first cycles, then lengthens. During the fifth phase, a person processes information and builds psychological protection, adapts to environment. Knowing how to calculate the sleep cycle, it is possible to learn how to regulate the body’s energy capacity and its vital functions as a whole.
Studies done on rats have shown that Lack of REM sleep leads to death. The rodents were deliberately awakened, preventing the rats from entering the fifth stage. Over time, the animals lost the ability to fall asleep, after which they died. If the sleeping person is deprived fast phase, then the person will become emotionally unstable, prone to irritation, mood swings, and tearfulness.
Girl sleeping with hand on alarm clock
How to calculate sleep phases to know when is the best time to wake up?
Let's take as a basis that one cycle lasts for 90 minutes. For good rest Long REM sleep is required. Therefore, at least 4 cycles should pass overnight. Waking up during slow-wave sleep makes a person groggy and lethargic. So, we need to calculate how to wake up during REM sleep: The fifth phase is characterized by active brain function, so awakening occurs gently and painlessly.
Let's summarize. To feel cheerful in the morning, the duration of sleep and awakening after the completion of the fifth phase are important. For an adult, the ideal sleep time is 7.5–8 hours. The best option- This self-awakening, no alarm or phone signal.
If during the day you feel weak and want to take a nap, then allow this luxury. To avoid harm, record your rest time. If you have slept enough time at night, close your eyes for 15–20 minutes. This is how long the first stage of slow-wave sleep lasts. You will not have time to fall asleep, but you will feel that fatigue has been relieved. If the night's sleep was short, then go through one cycle during the day. Sleep for 1–1.5 hours.
Conclusion
The data given is approximate, but the essence is clear. For normal life human body phase sleep is necessary. It is important to wake up after completing 4–5 cycles. It’s ideal when you wake up on your own. Daytime sleep will not harm you if you do not allow the second phase to enter or if you go through one full cycle.
January 20, 2014, 11:36An article on the topic: “slow-wave sleep and REM sleep. which is better than the different stages of sleep” from professionals.
Sleep is one of the most mysterious processes that occur in the human body. And one of the most significant, since we spend almost a third of our lives sleeping. And complete sleep deprivation, even for a relatively short period of time of a few days, can lead to neurotic disorders and imbalance of the entire body. Sleep is very difficult process, in which brain activity and vital body functions change. Scientists were able to identify the phases of slow and fast sleep, which have their own characteristics and purposes.
A little history
But even after scientists established that sleep is caused by the functioning of the human nervous system and brain and has nothing to do with the immortal soul, it was impossible to conduct full-fledged research due to the lack of suitable equipment. It was only in the second half of the 20th century that it became possible to record nerve impulses emanating from muscles and the brain, which made it possible to determine the level of their activity.
A lot of things have been done with the help of electrical appliances in the field of sleep. important discoveries. Rapid and slow-wave sleep were discovered, various types of insomnia were studied, and the processes occurring in the body during lethargic sleep were studied.
Scientists were able to reveal that human activity is regulated by circadian rhythms - daily alternations of periods of sleep and wakefulness, which continue to work even if it is impossible to navigate in time due to the lack of clocks and sunlight.
Computed tomography and magnetic resonance imaging have allowed us to study in more detail brain activity, which looks completely different during REM and slow-wave sleep. Interesting processes happen to a person when falling asleep, when the body and brain begin to slowly switch off and plunge into a state of deep relaxation, but at the same time certain parts of the brain continue to work.
But the most ambitious discovery was that the reactions of the brain and body to a vivid dream that a person sees in the REM phase are practically no different from reactions to real events. This means that a person literally “lives” his dream physically and mentally. But first things first.
Falling asleep
A person who wants to sleep is always easy to recognize, even if he tries to somehow hide his condition. Signs of drowsiness include:
A sleepy person begins to stretch, rub his eyes, and turn around in search of a position comfortable for falling asleep. This condition is associated with an increase in the concentration of a special hormone in the blood - melatonin. It gently inhibits the activity of the nervous system, promoting deeper relaxation and speeding up the process of falling asleep.
The hormone has virtually no effect on the quality of sleep itself. Melatonin is only a natural regulator of circadian rhythms.
The process of falling asleep in a healthy adult lasts from 20 to 40 minutes. If the duration of falling asleep remains constant for more than an hour, we can talk about the presence of one of the many forms of insomnia and it is better to take measures to eliminate it before it turns into chronic form. Natural products can help with this sedatives, taking additional doses of melatonin or proven folk remedies.
Slow phase
Having gone through the stage of falling asleep, a person plunges into slow-wave sleep. It gets its name from the slow rotation of the eyeballs that can be observed in a sleeping person. Although it's not just them. During slow-wave sleep, all vital functions of the body are inhibited - the body and brain relax and rest.As they studied this phase, scientists made more and more new discoveries. As a result, it was discovered that in infants slow sleep has only two stages, and in children over 1-1.5 years old and adults - as many as four, through which the body sequentially passes:
All four stages of the slow phase take approximately one and a half hours, plus or minus 10 minutes. Of this, approximately a fifth of the time is occupied by deep and very deep sleep, and the rest is superficial.
Moreover, a person usually goes through the first stage of slow-wave sleep only after falling asleep, and when slow and fast sleep alternate during the night, it “falls out.”
Fast phase
Scientists have not fully figured out what REM sleep is, how such strange processes can occur in the body, and what significance it has for humans. If everything is more or less clear with slow sleep - this is a period of active recovery of the body and complete relaxation, then the reactions of the brain and the vital functions of the body during REM sleep are completely different.
During REM sleep, a person's eyeballs under closed eyelids begin to move quickly along a chaotic trajectory. From the outside it seems that a person is closely watching something. In fact, this is so, since it is in this phase that dreams appear. But eye movement is not the only and far from the main difference between REM sleep.
What was seen on the encephalogram, and later on the tomogram of the brain during the fast phase, so amazed scientists that it received another name: “paradoxical sleep.” All readings during this period may be practically no different from those taken in a state of active wakefulness, but at the same time the person continues to sleep:
In fact, the entire body is “turned on” in the dream as if it were a real event, and only the person’s consciousness is turned off. But if you wake him up at this moment, he will be able to tell the plot of the dream in great detail and at the same time will experience emotional experiences.
Interestingly, it is during REM sleep that changes occur hormonal levels. Some scientists believe it is necessary for emotional "reset" and balancing endocrine system.
Having experienced exciting events again during sleep, a person then sends these memories to the subconscious, and they stop bothering him.
REM sleep also helps in regulating the level of sex hormones. Nocturnal erections, wet dreams and spontaneous orgasms occur during this phase. Moreover, they are not always accompanied by dreams of an erotic nature.
At the same time, most heart attacks or strokes occur, due to the fact that the relaxed heart and blood vessels are subjected to sudden stress.
At the beginning of the night, the fast phase does not last long - from 5 to 10 minutes, and a person spends most of the time after falling asleep in slow-wave sleep. But in the morning the phase relationship changes. The periods of REM sleep become longer and longer, and the periods of deep sleep become shorter and shorter, and at one point the person wakes up.
Proper awakening
An interesting fact is that a person’s activity and condition, especially in the first half of the day, depends on how he woke up. If he is awakened by external stimuli (alarm clock, bright light, sharp sounds, shock) during the slow phase of sleep, he still needs some time to “come to his senses.” In the first seconds, he may not even understand where he is, some parts of the brain are still so inhibited.
It is a completely different matter if the awakening occurs during REM sleep. The body is already alert and active, you just need to turn on your consciousness. A person who wakes up in this phase feels great, can quickly get out of bed and go about his business. At the same time, he perfectly remembers the last dream and can write it down or retell it.The modern rhythm of life places high demands on the level of physical activity. Perhaps that is why recently the so-called “ smart alarm clocks", which read the body's readings and send a signal just in the stage of REM sleep.
The advantage of such a device is that it greatly facilitates awakening, but the disadvantage is that it can wake a person up 20-30 minutes before the set time, since it begins to track sleep phases in advance, calculating the appropriate moment.
But even if you woke up easily, doctors do not advise jumping out of bed right away. Give the body 5-10 minutes for all organs and systems to smoothly start working. Stretch, lie down, tune in to the new day, go over your plans in your head again. And when you feel that you are completely ready for active actions, get up and move on to your morning routine.
Prevention of insomnia
Healthy quality sleep is considered to be a state in which a person quickly falls asleep and smoothly moves from one phase to another, waking up at the end of the night at his usual time on his own, without an alarm clock. Unfortunately, few people can boast of this today. Chronic fatigue, stress, poor nutrition, and negative emotions greatly reduce the quality of sleep and are becoming increasingly common causes of chronic insomnia.To avoid this problem and the multiple troubles associated with it - from neuroses to serious psychosomatic diseases, try to take at least basic measures that can ensure normal quality of sleep:
And most importantly, do not reach for sleeping pills even if you have been unable to fall asleep for several nights in a row. Such drugs quickly become addictive and in most cases deprive a person of the rapid phase of sleep.
Under the influence of a sleeping pill, a “heavy”, very deep sleep without dreams occurs, which is very different from normal - after it the person still feels broken.
If problems with falling asleep or frequent awakenings at night have become protracted, you are often tormented by nightmares, or your loved ones say that you walk at night, go to the doctor. The problem cannot be solved without finding out the cause that provoked it. And this can only be done after examination and consultation with several specialists: a neurologist, an endocrinologist, a somnologist.
But in most cases, temporary insomnia occurs as a result of stress or severe fatigue and can be easily dealt with using folk remedies: warm baths, milk at night, relaxing massage, aromatherapy. No less important is positive attitude. You can significantly improve the quality of your sleep simply by weaning yourself from thinking about problems in the evenings.
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We now know that nighttime sleep is a complex physiological process that includes up to five cycles. REM and NREM sleep. But more recently, in the 19th century, sleep was perceived by scientists as a phenomenon closed to study, in contrast to the waking state, which can be measured and observed.
You can assess the sleeping posture, measure his physical indicators: pulse, blood pressure, breathing rate, body temperature, but how to assess the fundamental processes of sleep itself?
The first experiments were based on awakening the subject, that is, on invading the sleep process.
However, through these studies, the understanding has been gained that sleep occurs in successive stages. Köllschütter, a German physiologist, established in the 19th century that sleep is deepest in the first hours, and later becomes more superficial.
A breakthrough in the history of sleep research was the discovery of electrical waves that originate in the brain and that can be recorded.
Scientists have the opportunity to observe, record and study phenomena that occur in a person’s sleep, without waking him up - using an electroencephalogram.
Numerous studies have found that A person's nighttime sleep consists of several alternating cycles of rapid and slow-wave sleep.
The cycle consists of four stages of slow-wave sleep and two stages of REM sleep.. At the beginning of the night's rest, slow-wave sleep predominates; in the morning the proportion of REM sleep increases.
slow sleep occupies 75 - 85% of all sleep and consists of:
naps,
sleepy spindles,
delta sleep,
deep delta sleep.
Many functions of our body change as we fall into sleep: during the stages of drowsiness and sleep spindles, the pulse becomes slower, blood pressure decreases, and blood flows slower.
As soon as the sleeper reaches delta sleep, the pulse quickens and the blood pressure rises.
REM sleep consists of two stages:
Emotional,
unemotional.
These stages replace each other several times, and the emotional phase is always longer.
If you display the depth of sleep using a curve, you will get several descents into deep sleep, followed by ascents into shallow REM sleep.
These ascents and descents take approximately an hour and a half.
Scientists suggest that the rhythm of one and a half hours is the main biorhythm and persists during wakefulness.
The phases of sleep do not replace each other directly, but through an intermediate state similar to drowsiness. This transitional stage in a healthy person takes up about 5 percent of all sleep.
When recognizing the stages of REM and slow-wave sleep, an important sign is the gradual relaxation of muscles or a decrease in muscle tone.
Adults have the following percentages between all sleep stages:
Napping – 12.1%,
sleep spindles – 38.1%,
delta sleep, – 14.2%,
deep delta sleep – 12.1%,
REM sleep – 23.5%
Differences between REM and NREM sleep.
NREM sleep has four distinct stages, and fast - two,
Eye movements in slow-wave sleep, smooth at first and completely freezing at the end of the stage, in REM sleep - the eyes move continuously,
State of the autonomic nervous system different in both stages.
In slow sleep we are growing faster: growth hormone produced by the pituitary gland is produced more actively in this phase.
Dreams are of a different nature.
In the fast phase, dream pictures are action-packed, brightly and emotionally colored, in the slow phase, the dream plot is calm or absent altogether.
Awakening.
If you wake a person in the middle of REM sleep, he will get up much easier and will feel much better than as a result of waking up in the slow phase.
Even if you've had enough time to sleep and you expect to feel a surge of strength and vigor, this will not happen if you wake up unsuccessfully at the beginning or in the middle of the slow-wave sleep cycle. In such a situation, you can hear: “Did you get up on the wrong foot?”
Apparently the cause of this condition is incomplete neurochemical processes that take place in slow-wave sleep.
Breath when falling asleep it becomes less frequent and louder, but less deep.
It slows down even more and becomes irregular in delta sleep.
Breathing in REM sleep is sometimes slow, sometimes frequent, sometimes with delays - this is how we react to the events of the dream we are watching.
Brain temperature decreases in slow-wave sleep, and in fast sleep, due to increased blood flow and active metabolism, it rises and sometimes exceeds the temperature during wakefulness.
Despite numerous differences, the stages of slow and fast sleep have a chemical, physiological, functional interdependence and belong to a single balanced system.
In slow sleep, the internal rhythms of every brain structure, every organ, every cell are regulated. During REM sleep, harmonious relationships are established between these structures, organs, and cells.
Based on materials from the book “Three Thirds of Life” by A. Wayne.
Elena Valve for the project Sleepy Cantata
Sleep is an essential human need. Its importance cannot be underestimated. Without sleep, a person will not be able to exist normally, and hallucinations will gradually appear. Researches sleep special science– somnology.
Sleep functions
First of all, the main function of sleep will be rest for the body, for the brain. During sleep, the brain will work in a certain way, creating special conditions for the body. Under these conditions, the following should occur:
- Rest of consciousness from daily activities.
- Finding solutions to open problems.
- Relaxation of body muscles.
- Release of the hormone melatonin.
- Stimulation of immunity at an adequate level.
- Consolidation of acquired knowledge in memory.
As already mentioned, without sleep a person cannot exist normally. Sleep also performs the function of regulating biorhythms.
Sleep disorders such as: insomnia, nightmares, sleepwalking, sleep paralysis, lethargic sleep, difficulty falling asleep will indicate that a person has any serious illnesses(most often of a neurological nature).
Stages of sleep. What do they have in common?
To date, scientists have found that there are 5 phases of sleep. Four of which are classified as slow-wave sleep, and one is classified as fast sleep.
When a person falls asleep, he enters the stages of slow-wave sleep, which vary in the degree of relaxation of the body and brain. Afterwards comes the REM sleep phase.
For proper rest, all phases must go through. In order for a person to wake up rested, he needs to get up after the REM phase, but in no case during the slow phase. If this happens, the person will get out of bed tired and irritated.
The most sound sleep, when it is extremely difficult to wake a person, will be observed in the middle of one of the sleep phases. During the period of falling asleep, a person can be very sensitive to surrounding stimuli, so for good sleep and the absence of insomnia, it is important to fall asleep in a quiet room.
The difference between slow-wave sleep and fast sleep
Different stages of sleep will be characterized by different indicators of brain activity, consciousness, state and muscle regulation.
NREM sleep suggests decreased brain activity and consciousness. During this phase, sleep paralysis occurs - the muscles are completely relaxed. This sleep phase will be characterized by the possible emergence of solutions to problem situations in real life, but since the brain will have reduced activity at this time, people often retain residual memories of the dream, fragments of it, but do not remember it completely.
By the fourth stage of the slow phase, the time of the lowest brain activity begins. It is very difficult to wake a person at this time, pathological conditions, such as: sleepwalking, nightmares, enuresis occur precisely during this phase of sleep. At this time, dreams occur, but a person most often completely forgets them, unless he suddenly wakes up by chance.
The main function of the slow phase of sleep is to restore the energy resources of a sleeping person.
The fast phase differs from the slow phase, first of all, presence of rapid movements of the eyeballs. Interestingly, during the rapid phase of sleep, brain activity becomes similar to its activity in the waking state. At this time, you can observe muscle spasms of the limbs and twitching in the sleeping person, which is the norm.
During the REM phase of sleep, people always have vivid and memorable dreams, which they can recount in detail after waking up.
Some scientists say that for proper sleep, you need, first of all, slow phase sleep, that REM sleep is a kind of rudiment. Other scientists say that this is fundamentally wrong - REM sleep has its own meaning.
Firstly, the significance of REM sleep dreams for the human psyche cannot be diminished. Psychologists, interpreting dreams, especially those that are frequently repeated, can give an accurate personal portrait of a person.
In dreams, a person can express himself, and sometimes a person realizes that he is sleeping, sometimes not, but this fact is very important for the human psyche.
In dreams, most often a person sees everyday reality transformed into symbols, so he can look at it, as they say, from the other side, which may lead to the solution of problems that are important to him.
Therefore, although radically different from each other, both phases of sleep are required for a good night’s rest; they complement each other perfectly.
How to get rid of sleep problems
It is very important to approach the process of falling asleep carefully - then problems with falling asleep will not arise. Difficulty falling asleep or insomnia can be avoided by following certain tips:
- A person should go to bed only when he wants to fall asleep.
- If a person cannot fall asleep, he should switch to some other activity until the desire to sleep appears.
- The room intended for rest should be quietly cool for comfortable falling asleep.
- The room should be dark - this is the main condition for the production of the sleep hormone.
In order to avoid night terrors, you will need to avoid watching programs that excite the nervous system and overeating; taking herbal sedatives and chamomile tea will have a good effect.
Sleep is one of the most amazing states, during which organs - and especially the brain - work in a special mode.
From a physiological point of view, sleep is one of the manifestations of the body’s self-regulation, subordinate to life rhythms, a deep disconnection of a person’s consciousness from external environment, necessary for restoring the activity of nerve cells.
Thanks to good sleep, memory is strengthened, concentration is maintained, cells are renewed, toxins are removed and fat cells, stress levels are reduced, the psyche is unloaded, melatonin is produced - the sleep hormone, regulator of circadian rhythms, antioxidant and immune protector.
Sleep duration according to age
Sleep serves as protection 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 will not only slow down, but hallucinations may also begin. Lack of sleep for 8-10 days drives a person crazy.
IN at different ages people need different quantities hours for sleep:
Unborn children sleep the most in the womb: up to 17 hours a day.
- Newborn babies sleep about the same amount: 14-16 hours.
- Babies between 3 and 11 months of age require 12 to 15 hours of sleep.
- At the age of 1-2 years – 11-14 hours.
- Preschoolers (3-5 years old) sleep 10-13 hours.
- Primary schoolchildren (6-13 years old) – 9-11 hours.
- Teenagers need 8-10 hours of rest at night.
- Adults (from 18 to 65 years old) – 7-9 hours.
- Elderly people over 65 years old – 7-8 hours.
Old people often suffer from insomnia due to ailments and physical inactivity during the day, so they sleep 5-7 hours, which in turn does not have the best impact on their health.
The value of sleep by hour
The value of sleep also depends on the time you go to bed: you can get enough sleep in an hour like a night or not get enough sleep at all. The table shows the phases of a person’s sleep by time of sleep efficiency:
| Time | The value of sleep |
| 19-20 hours | 7 o'clock |
| 20-21h. | 6 hours |
| 21-22 hours | 5 o'clock |
| 22-23 hours | 4 hours |
| 23-00 h. | 3 hours |
| 00-01h. | 2 hours |
| 01-02 hours | 1 hour |
| 02-03 hours | 30 minutes |
| 03-04 hours | 15 minutes |
| 04-05 hours | 7 minutes |
| 05-06 hours | 1 minute |
Our ancestors went to bed and got up according to the sun. Modern man goes to bed no earlier than one in the morning, the result is chronic fatigue, hypertension, oncology, neuroses.
With the actual value of sleep at least 8 hours, the body regained strength for the next day.
Some southern cultures have a tradition nap(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 that have their own psychophysiological characteristics. Each phase is distinguished by specific manifestations of brain activity aimed at restoring different parts of the brain and organs of the body.
When it is better for a person to wake up according to the phases of sleep, how easy the awakening will be depends on the phase in which his sleep was interrupted.
During deep delta sleep, awakening is the most difficult due to incomplete neurochemical processes that occur during this stage. And here It is quite easy to wake up during REM sleep, despite the fact that during this period the most vivid, memorable and emotional dreams occur.
However constant shortage REM sleep can be detrimental to mental health. It is this phase that is necessary to restore neural connections between consciousness and subconscious.
Phases of sleep in humans
The peculiarities of the functioning of the brain and the changes in its electromagnetic waves were studied after the invention of the electroencephalograph. An encephalogram clearly shows how changes in brain rhythms reflect the behavior and state of a sleeping person.
The main stages of sleep - slow and fast. They are uneven in duration. During sleep, the phases alternate, forming 4-5 wave-like cycles from 1.5 to less than 2 hours.
Each cycle consists of 4 phases of slow-wave sleep, associated with a gradual decrease in a person’s activity and immersion in sleep, and one of rapid sleep.
NREM sleep predominates in the initial sleep cycles and gradually decreases, while the duration of REM sleep increases in each cycle. The threshold for a person’s awakening changes from cycle to cycle.
The duration of the cycle from the beginning of slow-wave sleep to the end of fast sleep in healthy people is about 100 minutes.
- Stage 1 is about 10% of sleep,
- 2nd – about 50%,
- 3rd 20-25% and REM sleep - the remaining 15-20%.
Slow (deep) sleep
It is difficult to answer unambiguously how long deep sleep should last, because its duration depends on what sleep cycle a person is in, so in cycles 1-3, the duration of the deep sleep phase can be more than an hour, and with each subsequent cycle the duration of deep sleep is greatly reduced.
The phase of slow, or orthodox, sleep is divided into 4 stages: drowsiness, sleep spindles, delta sleep, deep delta sleep.
Signs of slow-wave sleep are loud and rare breathing, less deep than during wakefulness, a general decrease in temperature, a decrease in muscle activity, smooth eye movements that freeze towards the end of the phase.
In this case, dreams are unemotional or absent; long and slow waves occupy an increasing place on the encephalogram.
It was previously believed that the brain rests at this time, but studies of its activity during sleep have refuted this theory.
Stages of slow-wave sleep
In the formation of slow-wave sleep, the leading role is played by such areas of the brain as the hypothalamus, raphe nuclei, nonspecific nuclei of the thalamus and the Moruzzi inhibitory center.
The main characteristic of slow-wave sleep (aka deep sleep) is anabolism: creation of new cells and cellular structures, tissue restoration; it occurs at rest, under the influence of anabolic hormones (steroids, growth hormone, insulin), proteins and amino acids. Anabolism leads to the accumulation of energy in the body as opposed to catabolism, which consumes it.
The anabolic processes of slow sleep begin at stage 2, when the body completely relaxes and recovery processes become possible.
It was noticed, by the way, that active physical labor During the day, it prolongs the deep sleep phase.
The onset of falling asleep is regulated by circadian rhythms, and they, in turn, depend on natural light. The approach of darkness serves as a biological signal to reduce daytime activity, and the time for rest begins.
Sleepiness itself precedes falling asleep: a decrease motor activity and level of consciousness, dry mucous membranes, sticking eyelids, yawning, absent-mindedness, decreased sensitivity of the senses, slow heart rate, an irresistible desire to lie down, momentary lapses into sleep. This is how the active production of melatonin manifests itself in the pineal gland.
At this stage, the rhythms of the brain change insignificantly and you can return to wakefulness in a matter of seconds. Subsequent stages of deep sleep demonstrate an increasing loss of consciousness.
- Napping, or Non-REM(REM - from English rapid eye movement) - the 1st stage of falling asleep with half-asleep dreams and dream-like visions. Slow eye movements begin, body temperature decreases, and heartbeat, on the brain encephalogram, alpha rhythms that accompany wakefulness are replaced by theta rhythms (4-7 Hz), which indicate mental relaxation. In this state, a person often comes to a solution to a problem that he could not find during the day. A person can be brought out of slumber quite easily.
- Sleepy spindles – medium depth when consciousness begins to turn off, but the reaction to calling your child’s name or crying remains. The sleeper's body temperature and pulse rate decrease, muscle activity decreases; against the background of theta rhythms, the encephalogram reflects the appearance of sigma rhythms (these are altered alpha rhythms with a frequency of 12-18 Hz). Graphically, they resemble spindles; with each phase they appear less frequently, become wider in amplitude, and fade away.
- Delta– without dreams, in which the brain encephalogram shows deep and slow delta waves with a frequency of 1-3 Hz and a gradually decreasing number of spindles. The pulse quickens slightly, the breathing rate increases with a shallow depth, blood pressure decreases, and eye movements slow down even more. There is a blood flow to the muscles and active production of growth hormone, which indicates the restoration of energy costs.
- Deep delta sleep- complete immersion of a person into sleep. The phase is characterized by a complete shutdown of consciousness and a slowdown in the rhythm of delta wave oscillations on the encephalogram (less than 1 Hz). There is even no sensitivity to smells. The sleeping person's breathing is rare, irregular and shallow, and there is almost no movement of the eyeballs. This is a phase during which it is very difficult to wake a person. At the same time, he wakes up broken, poorly oriented in the environment and does not remember dreams. It is extremely rare in this phase that a person experiences nightmares, but they do not leave an emotional trace. The last two phases are often combined into one, and together they take 30-40 minutes. The usefulness of this stage of sleep affects the ability to remember information.
Stages of REM sleep
From the 4th stage of sleep, the sleeper briefly returns to the 2nd stage, and then the state of rapid eye movement sleep (REM sleep, or REM sleep) begins. In each subsequent cycle, the duration of REM sleep increases from 15 minutes to an hour, while sleep becomes less and less deep and the person approaches the threshold of awakening.
This phase is also called paradoxical, and here's why. The encephalogram again registers fast alpha waves with low amplitude, as during wakefulness, but at the same time the neurons of the spinal cord are completely turned off to prevent any movement: the human body becomes as relaxed as possible, muscle tone drops to zero, this is especially noticeable in the mouth and neck area .
Motor activity manifests itself only in the appearance of rapid eye movements(REM), during the period of REM sleep in a person, the movement of the pupils under the eyelids is clearly noticeable, in addition, body temperature rises, the activity of the cardiovascular system and the adrenal cortex increases. Brain temperature also rises and may even slightly exceed its waking level. Breathing becomes either fast or slow, depending on the plot of the dream that the sleeper sees.
Dreams are usually vivid, with meaning and elements of fantasy. If a person is awakened in this phase of sleep, he will be able to remember and tell in detail what he dreamed.
People who are blind from birth do not have REM sleep, and their dreams consist not of visual, but of auditory and tactile sensations.
In this phase, the information received during the day is adjusted between the conscious and subconscious, and the process of distributing the energy accumulated in the slow, anabolic phase takes place.
Experiments on mice confirm that REM sleep is much more important than non-REM sleep. That is why awakening in this phase artificially is unfavorable.
Sequence of sleep stages
The sequence of sleep stages is the same in healthy adults. However, age and various sleep disorders can fundamentally change the picture.
Newborn sleep, for example, consists of more than 50% REM sleep., only by the age of 5 the duration and sequence of stages becomes the same as in adults, and remains in this form until old age.
In older years, the duration of the rapid phase decreases to 17-18%, and the phases of delta sleep may disappear: this is how age-related insomnia manifests itself.
There are people who, as a result of a head or spinal cord injury, cannot sleep fully (their sleep is similar to light and brief oblivion or half-asleep without dreams) or go without sleep at all.
Some people experience numerous and prolonged awakenings, due to which a person is completely sure that he did not sleep a wink during the night. Moreover, each of them can wake up not only during the REM sleep phase.
Narcolepsy and apnia are diseases that demonstrate atypical progression of sleep stages.
In the case of narcolepsy, the patient suddenly enters the REM phase and can fall asleep anywhere and at any time, which can be fatal for him and those around him.
Apnia is characterized by sudden stop breathing in sleep. Among the reasons are a delay in the respiratory impulse coming from the brain to the diaphragm, or excessive relaxation of the muscles of the larynx. A decrease in the level of oxygen in the blood provokes a sharp release of hormones into the blood, and this forces the sleeper to wake up.
There can be up to 100 such attacks per night, and they are not always recognized by the person, but in general the patient does not receive proper rest due to the absence or insufficiency of certain phases of sleep.
If you have apnea, it is very dangerous to use sleeping pills; they can cause death from sleep apnea.
Also, the duration and sequence of sleep stages can be influenced by emotional predisposition. People with “thin skin” and those who are temporarily experiencing difficulties in life have an extended REM phase. And in manic states, the REM stage is reduced to 15-20 minutes throughout the night.
Rules for healthy sleep
Adequate sleep is health strong nerves, good immunity and an optimistic outlook on life. You should not think that time passes in a dream uselessly. Lack of sleep can not only have a detrimental effect on your health, but also cause tragedy..
There are several rules for healthy sleep that ensure sound sleep at night and, as a result, excellent health and high performance during the day:
- Stick to a bedtime and wake-up schedule. It is best to go to bed no later than 11 pm, and all sleep should take at least 8, ideally 9 hours.
- Sleep must necessarily cover the period from midnight to five in the morning, during these hours it produces maximum amount melatonin – the hormone of longevity.
- You should not eat food 2 hours before bedtime, V as a last resort, drink a glass of warm milk. It is best to avoid alcohol and caffeine in the evening.
- An evening walk will help you fall asleep faster.
- If you have difficulty falling asleep, it is advisable to take a warm bath before bed with an infusion of soothing herbs (motherwort, oregano, chamomile, lemon balm) and sea salt.
- Be sure to ventilate the room before going to bed. You can sleep with the window slightly open and the door closed, or open the window in the next room (or in the kitchen) and the door. To avoid catching a cold, it is better to sleep in socks. The temperature in the bedroom should not fall below +18 C.
- It is healthier to sleep on a flat and hard surface, and use a bolster instead of a pillow.
- Stomach position is the worst position for sleeping, the position on your back is most beneficial.
- After waking up, a small exercise stress: exercise or jogging, and, if possible, swimming.
Daily healthy sleep is a vital need of the human body. At this time, the activity of the heart muscle decreases, brain activity slows down, and all muscle groups relax. When a person sleeps, accelerated cell division occurs, which are responsible for fighting bacteria and viruses. Sleep normalizes hormonal levels and helps the body readjust and prepare for changing weather and changes in the length of daylight hours.
Physiologists were able to study such a complex phenomenon in detail relatively recently, when electrical waves arising in the brain were discovered and devices capable of recording them were designed. The result of the research was the identification of slow and fast cycles, the alternation of which constitutes the sleep of any person.
Main phases of the slow cycle
After a person falls asleep, a period of slow-wave sleep begins. It is so called because the movement of the eyeballs is slowed down to a complete stop. But not only the eyes, but all body systems relax as much as possible, reactions are inhibited. The entire period of slow-wave sleep for an adult is usually divided into four phases:
- Alpha sleep or nap. The encephalogram shows a predominance of alpha rhythms, which characterize the state of the brain during the daytime active life. Gradually they fade and are replaced by theta rhythms, which characterize the state of deep sleep. During this transition interval, the process of relaxation of the body muscles occurs. A person experiences the familiar sensation of flying and falling. While fragmentary thoughts remain in the brain, the information received during the day is processed and conjectured.
- Sleep spindles or light sleep. Sensitivity to external stimuli still remains; a person can easily wake up from a sharp sound or touch. If there are no interferences, then the process of falling asleep develops, the level of blood pressure decreases, the work of the heart muscle slows down, and breathing becomes deep and intermittent. The eyeballs rotate more and more slowly.
- Delta sleep. This phase is characterized by the predominance of delta rhythms on the brain encephalogram, characteristic of very deep sleep.
- Very deep. Characterized by complete relaxation of all body systems, a sleeping person is practically impossible to awaken. The main feature of this period is the launch of recovery processes. In this phase, information that is stored in the subconscious becomes available. This can cause nightmares or conversations in a sleeping person.
The duration of all four phases is about one and a half hours. At the same time, very deep sleep takes 18-20 minutes.
Characteristics of a fast cycle
REM sleep is fundamentally different from slow sleep. All readings taken while the body is in the REM sleep cycle correspond to similar readings that were recorded during active wakefulness. The body’s transition to a fast cycle is characterized by the following processes:
- Blood pressure rises sharply;
- Muscles tense, tone increases;
- Are becoming more active various areas brain;
- Heart rate accelerates;
- Breathing becomes frequent and shallow;
- The eyeballs roll restlessly.
During REM sleep, dreams occur. It is interesting that the consciousness of the sleeping person is turned off, however, a suddenly awakened person can tell in detail what he dreamed. At its first onset, the rapid cycle takes a very short period of time, but then the situation changes. The slow stage gradually decreases, and the fast stage increases. Of the total duration of night rest, slow sleep accounts for 75-80%.
Which sleep is more beneficial for a person?
There is no clear answer to the question of which of the two cycles is better - slow or fast. These are two phases of a natural physiological process that are interconnected and complement each other. Slow promotes the complete restoration of all functions of the human body. When the REM sleep phase begins, scientists observe changes in the state of a person’s hormonal levels. Physiologists believe that this cycle is necessary to regulate the endocrine system. However, at this stage, due to a sharp increase in pressure and acceleration of heart contractions, heart attacks and strokes occur more often.
Which sleep is best for waking up?
Well-being and mood depend on the phase in which awakening occurred. Physiological scientists do not recommend waking up during REM sleep. The best time to wake up is during the transition from REM to NREM sleep. To wake up on its own, the body of a healthy person chooses this convenient time. Waking up immediately after a dream, a person is cheerful and cheerful, remembers everything he saw perfectly and can retell it. All systems are already operating in active daytime mode. A person who wakes up to the sound of an alarm clock in the deep sleep stage will look lethargic and sleep-deprived all day. In the first moments, he may not understand where he is and what is happening. All body systems are relaxed, basic functions are inhibited, and recovery will take time. Nowadays, so-called “smart” alarm clocks have appeared and are becoming popular. They read the brain of a sleeping person and wake him up at the most appropriate moment, at the end of the fast cycle.
How to get rid of insomnia
Healthy sleep is the state of a person when, having gone to bed at a certain time, he quickly falls asleep, goes through about six changes of slow and fast phases during the night and wakes up on his own at the end of the fast phase. However, many factors modern life– poor nutrition, lack of physical activity, chronic fatigue, stress prevent proper sleep and cause insomnia. It can cause various Negative consequences: from neuroses to serious somatic diseases.
The main methods of combating insomnia at the initial stage are:
- Elimination of external irritants;
- Ventilate the room before going to bed;
- Allocate at least 7 – 8 hours for night rest;
- Falling asleep no later than 24 hours;
- Organization of a comfortable sleeping place;
- Waking up on your own if possible;
- Quitting alcohol and smoking at night, they disrupt the correct alternation of phases;
- Yoga, meditation.
The developed habit of not thinking about problems at night, as well as regular evening walks, can significantly improve the quality of sleep. If there is no improvement, you should consult a doctor. Under no circumstances should you take sleeping pills on your own. Under their influence, a heavy, abnormally deep sleep occurs, after which the person wakes up broken.
People spend a third of their lives sleeping. But until now this complex and to some extent magical phenomenon has not been fully studied. What happens to the human body and brain when he closes his eyes at night and falls asleep remains a mystery in many respects.
The main findings from years of numerous and varied sleep studies are as follows. Sleep is not a break in brain activity, it is simply a different state. During sleep, the brain goes through several different phases, or stages, of activity that repeat in approximately one-and-a-half-hour cycles. Sleep consists of two qualitatively different states called NREM and REM sleep. They differ in total electrical activity of the brain (EEG), eye motor activity (EOG), muscle tone and numerous autonomic indicators (heart rate and respiration, electrical activity of the skin, etc.; see Chapter 2).
slow sleep is divided into several stages, identified on the basis of EEG changes (Fig. 13.2) and differing in depth. In the first stage, the main bioelectrical rhythm of wakefulness, the alpha rhythm, disappears. It is replaced by low-amplitude oscillations different frequencies. This is the stage of drowsiness, falling asleep. In this case, a person may experience dream-like hallucinations. The second stage (shallow sleep) is characterized by the regular appearance of a spindle-shaped rhythm of 14-18 vibrations per second (“sleepy” spindles). With the appearance of the first spindles, consciousness switches off; During pauses between spindles, a person can easily be awakened. The third and fourth stages are combined under the name delta sleep, because during these stages high-amplitude slow waves - delta waves - appear on the EEG. In the third stage, they occupy from 30% to 50% of the entire EEG. In the fourth stage, delta waves occupy more than 50% of the entire EEG. This is the most deep stage sleep, here is the highest threshold of awakening, the most powerful disconnection from the outside world. When waking up at this stage, a person has difficulty finding his bearings and compresses time to the greatest extent (underestimates the duration of the previous sleep). Delta sleep predominates in the first half of the night. At the same time, muscle tone decreases, breathing and pulse become regular and slow, body temperature decreases (by an average of 0.5°), eye movements are absent, and a spontaneous galvanic skin reaction can be recorded.
REM sleep- The very last stage in the sleep cycle. It is characterized by fast, low-amplitude EEG rhythms, making it similar to the waking EEG. Cerebral blood flow increases, and against the background of deep muscle relaxation, powerful activation of autonomics is observed. In addition to the tonic components of the REM sleep stage, phasic components are identified - rapid movements of the eyeballs with closed eyelids (REM, or REM-rapid eye movements), muscle twitching in separate groups muscles, sudden changes heart rate (from tachycardia to bradycardia) and breathing (a series of frequent inhalations and exhalations, then a pause), episodic rises and falls in blood pressure, erection of the penis in men and clitoris in women. The awakening threshold ranges from high to low. It is at this stage that most memorable dreams occur. Synonyms for REM sleep are paradoxical (the activated nature of the EEG with complete muscle atonia), REM, or REM sleep, rhombencephalic (due to the localization of regulatory mechanisms).
The entire night's sleep consists of 4-5 cycles, each of which begins with the first stages of slow sleep and ends with REM sleep. Each cycle lasts about 90-100 minutes. In the first two cycles, delta sleep predominates; episodes of REM sleep are relatively short. In the last cycles, REM sleep predominates, and delta sleep is sharply reduced and may be absent (Fig. 13.2). Unlike many animals, humans do not wake up after each sleep cycle. The structure of sleep in healthy people is more or less similar - stage 1 takes up 5-10% of sleep, stage 2 - 40-50%, delta sleep - 20-25%, REM sleep - 17-25%.
Rice. 13.2. Sleep phases:
EEG during different stages of sleep (top). Changes in sleep depth throughout the night, lengthening periods of REM sleep (bottom) [after Bloom et al., 1988]
Thus, every night we dream 4-5 times, and “looking at” dreams takes a total of 1 to 2 hours. People who claim that they dream very rarely simply do not wake up in the dreaming phase. The intensity of the dreams themselves, the degree of their unusualness and emotional richness may vary, but the fact of their regular occurrence during sleep is beyond doubt.
The idea, widespread in the past, that sleep is necessary for the “rest” of brain neurons and is characterized by a decrease in their activity, has not been confirmed by studies of non-ironal activity. During sleep, in general, there is no decrease in the average frequency of neuronal activity compared to the state of quiet wakefulness. In REM sleep, spontaneous neuronal activity can be higher than in intense wakefulness. In slow-wave sleep and rapid eye movement sleep, the activity of different neurons is organized differently (see Chapter 8).
In addition to electrophysiological ones, certain stages of sleep are characterized by certain hormonal changes. Thus, during delta sleep, the secretion of growth hormone, which stimulates tissue metabolism, is increased. During REM sleep, the secretion of hormones from the adrenal cortex is increased, which increases during wakefulness under stress. The intensity of energy metabolism in the brain tissue during slow-wave sleep is almost the same as in a state of quiet wakefulness, and during REM sleep it is much higher.
Thus, it can be argued that the brain is active during sleep, although this activity is qualitatively different than during wakefulness, and in different stages sleep has its own specifics.
Sleep in onto- and phytogenesis
During ontogenesis, the sleep-wake ratio changes. Thus, in newborns, the state of wakefulness constitutes only a small part of the day, and a significant part of sleep is occupied by REM sleep. As you grow older, the total amount of sleep decreases, the ratio of phases within the sleep cycle changes - REM sleep decreases and slow-wave sleep relatively increases; by the age of 14, the sleep cycle reaches 90 minutes. In an adult, as already mentioned, REM sleep takes up about 1/4 of the total sleep time. In old age, there is a decrease in the total amount of sleep, and both slow and fast sleep are reduced. After 75 years, neurotic insomnia is often observed - slow-wave sleep is reduced, sleep becomes intermittent, and sleep cycles are disrupted.
Alternating periods of activity and rest occur in all living beings; Perhaps periods of rest are analogues of slow-wave sleep. In one form or another, sleep is observed in all vertebrates. But sleep, consisting of several cycles, within which the stages of slow and fast sleep unfold, is characteristic only of warm-blooded animals. In its organization, the sleep of mammals and birds does not differ from human sleep, although slow-wave sleep in animals is less differentiated, the percentage of slow and fast sleep varies in different animals, and sleep cycles are usually shorter. “A short, intense life goes hand in hand with long sleep and a short sleep cycle” [Borbeli, 1989, p. 97]. In a rat, the sleep cycle lasts 12 minutes, in a dog - 30 minutes, in an elephant - about 2 hours. Peculiarities of sleep organization are related to the ecology of animals.
In birds, periods of REM sleep are very short - at the same time, due to complete muscle atonia, the head drops and the wings fall. If a bird sits on a branch, then as the tone of the leg muscles decreases, the toes contract, and the bird can sleep without falling from the branch.
The sleep of ungulates is also associated with their way of life - gregariousness, fear of predators - and has the character of “ragged” sleep (after each sleep cycle the animal raises its head and looks around, so at any given moment some individuals are necessarily awake). The nature of plant foods requires prolonged chewing, and the superficial stages of sleep occur in ruminants during chewing.
Burrowing mammals have a well-defined cyclicity, they sleep a lot, and REM sleep takes up to 1/3 of the total sleep time. Many of them are characterized by seasonal hibernation. It is characterized by loss of the ability to thermoregulate, a sharp decrease in the amount breathing movements and heart rate, a drop in the overall level of metabolism. Some large mammals(bears, raccoons, partly badgers) seasonal sleep, or facultative hibernation, is observed. In this case, body temperature, the number of respiratory movements and the general level of metabolic phenomena decrease slightly. If external conditions change, such sleep can easily be interrupted.
The sleep patterns of marine mammals are also related to their ecology. For each act of breathing, both during sleep and during wakefulness, they must float to the surface to point their nostrils into the air. Depending on the lifestyle arose different shapes adaptation. Thus, during electrophysiological recording of sleep in dolphins, L. Mukhametov discovered the phenomenon of “unihemispheric” sleep - delta waves arose only in one hemisphere (alternately in the right or left). At the same time, in the other hemisphere the EEG pattern corresponded to the superficial stages of slow-wave sleep or wakefulness. EEG corresponding to the superficial stages of slow-wave sleep could be observed in both hemispheres simultaneously; No signs of REM sleep could be detected. The same “one-hemisphere” slow-wave sleep appears in the so-called eared seals (seals and sea lions) when they are in the pool and cannot go to land. When they sleep on land, in both hemispheres they have an EEG characteristic of normal slow-wave sleep; Many episodes of REM sleep are recorded.
In seals and sea lions, which spend only part of their lives in water, their entire sleep cycle develops during the respiratory pause. They “breathe out” well by doing several deep breaths, and dive. In 15-20 minutes, the stages of slow sleep and rapid sleep change, and they emerge for the next “breathing”.
Thus, sleep is vital for highly organized animals. At the same time, the sleep characteristics of various animals reflect its adaptive nature to living conditions and environmental factors.
Need for sleep
Many people would like to sleep less, since sleep, in their opinion, is time lost from life. Others, on the contrary, would like to sleep more because they do not feel well enough.
“We are chronically sleep deprived”; "Should we sleep more?" are the titles of two articles recently published in the journal Sleep, reflecting polarized attitudes to the issue of sleep duration. One of the usual maxims in sleep medicine is that our modern society is severely sleep deprived, and this affects the human condition and society, being a significant cause of accidents and disasters. This point of view is supported by numerous studies showing the negative effects of sleep deprivation on the mood of subjects and their performance of psychomotor tasks. Using various psychological tests, it has been shown that if the duration of night sleep is reduced by 1.3-1.5 hours, this affects the state of vigilance during the day. Recent studies on the required duration of sleep have shown that the average sleep requirement among young people is 8.5 hours per night. A night's sleep duration of 7.2-7.4 hours is insufficient, and sleeping less than 6.5 hours for a long time can undermine health. Another point of view is that most people do not have chronic sleep deprivation, but they may sleep more, just as we eat and drink beyond our physiological needs. This is based on significant individual variations in sleep needs, as well as the fact that after long periods of sleep, improvements in daytime alertness are minimal, and fatigue is successfully eliminated by short breaks from work.
The effect of “accumulation of sleep deprivation” completely disappears after the first 10-hour period of “restorative” sleep. That's why chronic lack of sleep on weekdays and oversleeping on weekend mornings are interconnected phenomena. Nevertheless, the statement of the committee “Disasters, Sleep and Public Policy” created in the USA emphasizes that even a slight chronic lack of sleep for 1-2 hours is fraught with serious disruptions in work if it constantly requires a high level of concentration and attention [Kovalzon, 1989].
Sleep deprivation
Experiments with deprivation (artificial sleep deprivation) suggest that the body has a special need for delta sleep and REM sleep. After prolonged sleep deprivation, the main effect is an increase in delta sleep. Thus, after 200 hours of continuous wakefulness, the percentage of delta sleep in the first 9 hours of recording recovery sleep increased 2 times compared to the norm, and the duration of REM sleep increased by 57%. Deprivation of less than 100 hours did not cause an increase in the duration of REM sleep on the first recovery night. As the total amount of sleep decreases, the duration of delta sleep does not change or even increases, and the duration of REM sleep decreases.
In order to study the role of individual sleep phases, methods have been developed to selectively prevent their occurrence. To suppress delta sleep, the “stimulation” method is used - when delta waves appear on the EEG, sound signals of such intensity are given to ensure a transition to more superficial stages of sleep. At the same time, the subjects develop a feeling of weakness, fatigue, memory deteriorates and attention decreases. Research by V. Rotenberg shows that the feeling of being overwhelmed and increased fatigue, especially increasing in the afternoon, in patients with neurosis is due to a chronic deficit of delta sleep [Rotenberg, 1984].
To exclude REM sleep, a person or animal is woken up at the first signs of this sleep phase - the appearance of rapid eye movements and a drop in muscle tone. REM sleep deprivation in animals is usually carried out according to the method proposed by M. Jouvet. The animal (most often rats are used in these experiments) is placed on a small area surrounded by water and adapts to sleep on it. But at the very beginning of each episode of REM sleep, as soon as the animal’s muscle tone drops, it collapses into cold water and immediately wakes up. As a result, the animal can be deprived of the REM sleep phase for many days without significantly disrupting slow-wave sleep. After such deprivation, the animals showed increased excitability, aggressiveness, and motor restlessness, i.e., symptoms of severe stress. In order to separate the effect of deprivation of REM sleep from the effect of stress (the hopeless situation of being in a limited area with inevitable falls into the water), V. Kovalzon developed a method of REM sleep deprivation without stress - irritation of the activating reticular formation of the brain stem with weak pulses of electric current that awakens the animal upon the onset of REM sleep.
At the same time, the rats were in a spacious experimental cage, during periods of wakefulness they drank, ate, played normally, and they had no symptoms of stress - their fur was shiny, their weight did not decrease. The duration of REM sleep was reduced by 3 times while slow-wave sleep was maintained. Despite the absence of any behavioral symptoms of REM sleep deprivation, the number of attempts to transition to REM sleep increased day by day, and the awakening threshold increased.
With selective deprivation of REM sleep, a person's need for it increases, although no mental disorders can be detected. However, in the first experiments with REM sleep deprivation in humans (conducted by V. Dement on three subjects continuously for several days), significant changes in the psyche were discovered - increased irritability, absent-mindedness, the appearance of hallucinations and crazy ideas. It later turned out that these subjects were not completely healthy. When studies were carried out on healthy subjects, it turned out that REM sleep deprivation “not only does not lead to mental disorders, but does not have any effect on mental state- does not change mood, does not impair task performance, does not affect memory or performance. The more comfortable the conditions were during the period of deprivation, the more carefully the experimenters ensured that all the needs of the subjects were met, the more exciting and varied the pastime was during the study period, the less the effect of deprivation affected” [Rotenberg, Arshavsky, 1984, p. 86].
When the results of REM sleep deprivation began to be analyzed individually, due to personal characteristics subjects, certain differences were found. Thus, R. Cartwright and colleagues found that REM sleep deprivation causes various changes in the psyche and behavior depending on the initial mental status. Anxious subjects responded to deprivation with a significant increase in anxiety; they tried to immediately compensate for the interrupted REM sleep. Subjects of the other type did not have significant behavioral disturbances, and a compensatory increase in REM sleep was detected on the recovery night. Finally, the third type did not show behavioral disturbances, did not attempt to immediately compensate for REM sleep or increase REM sleep on the recovery night, but when awakening before the first manifestations of REM sleep, they gave detailed reports of dreams. Obviously, their dreams took place in slow-wave sleep, and this replaced their need for REM sleep.
The importance of REM sleep for health was shown by E. Hartmann, identifying two extreme groups among healthy subjects - “long sleepers” (who wellness you need at least 9 hours of sleep), and “short sleepers” (6 hours of sleep is enough). In terms of sleep structure, these people differed mainly in the duration of REM sleep - for long sleepers it took almost twice as long. When analyzing their mental characteristics, it turned out that, compared to short sleepers, they were emotionally less stable - they took all problems to heart, were characterized by restlessness, anxiety and mood swings. One got the impression that in their dreams they were escaping the difficulties of life, i.e. “they went to bed as neurotics and woke up as healthy people.” Hartmann suggested that this recovery of mental health from evening to morning is determined by the high presence of REM sleep in their nightly sleep. By interviewing healthy people whose sleep duration was not constant throughout their lives, Hartmann found that a reduction in sleep usually occurs during periods when a person feels good, works with interest and is free from anxiety. The need for sleep increases when insoluble problems arise, mood and performance decrease.
Dreams
Dreams have long amazed and worried people. In ancient times, dreams were seen as “the gateway to another world”; It was believed that through dreams contact with other worlds could occur. For a long time people have tried to induce dreams using certain ritual formulations; similar formulations are found even in texts dating back to around the 3rd millennium BC. e. Already the first civilizations of the Middle East, Egypt, India and China left some records about dreams and methods of inducing them. For example, a special prayer of the ancient Assyrians is known for inducing good dreams and getting rid of unpleasant ones [Garfield, 1994]. The ancient world was full of beliefs in dreams, and in Ancient Greece dreams played a leading role even in the development of laws. “Prophetic dreams” that predicted the development of future events acquired great importance. However, Aristotle already taught that dreams are not the “language of the gods” or the “journey of the soul,” but phenomena arising from the very essence of the human spirit, which are the result of the special activity of the human brain, especially his senses. In his treatise “On Dreams and Their Interpretation,” Aristotle tried to understand the very nature of dreams (see [Anokhin, 1945]). The attention of ancient thinkers was focused mainly on questions about the origin of dreams and the ability to predict events. These same questions concern people today.
The results of numerous studies suggest that one of the main functions of dreams is emotional stabilization [Rotenberg, 1984]. This is well stated by Roberts [cit. from: Borbeli, p. 53]: “A person deprived of the ability to dream will, after a while, fall into madness, for a mass of unformed, fragmentary thoughts and superficial impressions will accumulate in his brain and suppress those thoughts that should be completely preserved in memory.” For the first time, systematic research into the role of dreams was undertaken by the founder of psychoanalysis, Z. Freud. Considering dreams as a special and very important language of the brain, he noted that dreams are the product of our own mental activity and at the same time the completed dream strikes us as something external to us. In his work “The Interpretation of Dreams” 3. Freud showed that dreams contain not only a clear, obvious meaning that can be stated in a retelling, but also a hidden, implicit one that cannot be immediately realized or understood. To understand this second meaning, it is necessary Additional Information about the identity of the one who saw this dream. Based on this, using the method of “free associations,” the psychoanalyst leads the patient to the awareness of repressed desires hidden in the dream, which relieves emotional tension.
Modern psychotherapists and psychoanalysts came to the conclusion that dreams can be controlled. An example is the attitude towards dreams in the Sinoan tribe in Malaysia, where each member of the tribe knows how to destroy nightmares [Garfield, 1994]. The Shinoi teach their children to perceive dreams as an important part of personality formation and have managed to organize their lives in such a way that they do not have mental illness.
A powerful impetus for the experimental study of dreams was the discovery of REM sleep and its connection with dreams. It became possible to receive reports on dreams immediately after their completion. It was discovered, to the surprise of those who thought that they did not dream or dreamed very rarely, that every person dreams several times a night. The question of the duration of dreams was also resolved experimentally. It turned out that the subjective duration of dreams corresponds to the objective duration of the REM sleep period. A subject awakened at the beginning of a period of REM sleep reports a short dream, and one awakened at the end reports a long one. After very long episodes of REM sleep (30-50 minutes), subjects reported unusually long dreams. Interestingly, reports of the content of these dreams were no longer than when subjects were awakened as early as 15 minutes after the onset of REM sleep. Apparently, dreams begin to be forgotten despite the continuation of a long episode of REM sleep. Numerous experiments indicate that the content of dreams correlates with the characteristics of the phasic components of REM sleep. It has been shown that the degree of emotional coloring of dreams is associated with heart rate and breathing, the degree of vasoconstriction and the severity of electrical activity of the skin in the last minutes of REM sleep before awakening.
Apparently, animals also have dreams during REM sleep - this is evidenced by M. Jouvet’s experiments with the destruction of the nuclei of the blue spot (locus coeruleus) in cats, which ensures the suppression of muscle tone in the REM sleep phase. A sleeping animal with a destroyed blue spot rose to its paws with the onset of REM sleep. eyes closed, sniffed, scratched the floor of the cell, made sudden jumps, as if chasing an enemy or escaping from danger. These data, as well as the results of numerous laboratory studies of sleep in humans, suggest that REM sleep is the physiological basis of dreams.
However, it is a simplification to consider REM sleep as the only phase of sleep with dreams, since subjects also report dreaming when awakening from slow-wave sleep. But reports of dreams in REM sleep are more vivid, more complex, fantastical, and more emotionally charged compared to dreams in slow-wave sleep, where rational and realistic elements, similar to waking thinking, predominate. The main difference lies in their duration - dreams in REM sleep are longer. Apparently, this explains the fact that when waking up from REM sleep, dreams are better remembered.
A phenomenon, in a certain sense opposite to dreams, is somnambulism (sleepwalking, or sleepwalking). Laboratory research showed that somnambulism occurs against the background of delta sleep; The severity and duration of the attack varies significantly. In the mildest case, a person can sit up in bed, mutter something and fall asleep again - in such cases, the EEG shows a picture of deep delta sleep. In other cases, the somnambulist gets up, walks, can get dressed and leave the house (in this case, the eyes are usually open, the face is mask-like); a somnambulist can give monosyllabic answers to simple questions - in such cases, signs of drowsiness or even wakefulness appear on the EEG. In the morning, the somnambulist does not remember anything about what happened to him at night. In contrast to dreams, with their world saturated with bright colors and events with complete muscle atonia, somnambulism is characterized by a twilight state of consciousness (which is not recorded in memory at all) while maintaining the ability to move as if awake. The existence of two extreme phenomena (dreams and somnambulism) indicates that sleep is a whole set of different states, among which there are deep dive into the inner world, and demonstration of external activity.
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