Deep sleep state. Characteristic features of the slow phase of human sleep. When is the best time to wake up: in the stage of non-REM or REM sleep

Scientists have paid attention to sleep relatively recently, which is strange, given how much of our lives we spend in a dream. After the scientific interest in sleep processes arose, so-called sleep centers appeared at Harvard and the University of Pennsylvania, numerous studies were carried out and conclusions were drawn. In this article, you'll learn what the science of sleep is, why many people can't fall asleep, and some practical exercises for healthy sleep and more energy.

First steps in the science of sleep

The pioneer of chronobiology was the French scientist Michel Siffre, who studied biological rhythms in a harsh experiment on himself. He lived in an underground cave with a bed, a table, a chair, and a phone to call his research team.

Michel Siffre during the experiment

His underground home was lit with just one light bulb with a soft glow. From food - frozen foods, a few liters of water. There were no clocks, no calendars, and no way of knowing what time it was on the surface, day or night. And so he lived alone for several months.

A few days after descending into the cave, Siffre's biological clock began to work. He later recalled how he felt during the experiment:

My sleep was wonderful. My body itself chose when to sleep and when to eat. It is very important. My cycle of sleep and wake up did not last 24 hours, like people on the surface of the earth, but a little longer - about 24 hours and 30 minutes.

Thus, despite the absence of sunlight and any knowledge of whether it was day or night, his circadian rhythms continued to work.

After this experiment, many scientists became interested in the study of sleep. New research has helped to figure out how much sleep you need, why you need to do it and how you can make up for the lack of sleep.

How much sleep do you need

How much sleep do you really need? To answer this question, let's turn to the experiment of scientists from the University of Pennsylvania and the University of Washington.

The researchers collected 48 healthy men and women who were accustomed to sleeping 7-8 hours a night. The participants were then divided into four groups.

People from the first group had to go without sleep for three days, from the second - to sleep 4 hours a day. Participants from the third group were allowed to sleep for 6 hours a day, and from the fourth - for 8 hours.

The three groups, who slept 4, 6, and 8 hours a day, had to do this for two weeks. During the experiment, scientists observed the physical health and behavior of the participants.

As a result, the group of participants who slept for 8 hours a day did not experience any impairment during the entire experiment - cognitive decline, deterioration in reaction, or memory lapses. At the same time, in people who slept 6 and 4 hours a day, all indicators gradually worsened.

The 4-hour sleep group performed worse, although not by much, than the 6-hour group. In general, two significant conclusions were drawn from the experiment.

First, lack of sleep tends to accumulate. In other words, sleep deprivation has a neurobiological cost that only increases over time.

After one week of the experiment, 25% of the participants who slept 6 hours a day fell asleep intermittently at various times during the day. After two weeks, people in this group had the same performance as if they had spent two days without sleep at all.

The lack of sleep gradually accumulates.

The second conclusion is no less important: the participants did not notice a decrease in their performance. The participants themselves believed that their performance deteriorated over several days, and then remained at the same level. In fact, their performance continued to decline throughout the experiment.

We don't notice cognitive decline with lack of sleep.

It turns out that we assess our condition very poorly and cannot accurately determine how well our cognitive functions are working. Especially in today's environment of constant social activity, caffeine and many other factors that help to feel fresh and alert, even if in fact it is far from being the case.

The cost of lack of sleep

The irony is that many of us suffer from lack of sleep in an effort to earn more. But no matter how many extra hours you spend working instead of getting enough sleep, it will not increase your productivity much. Your attention, memory and other functions deteriorate, and you do all tasks more slowly and worse.

Studies have found that reduced work efficiency due to lack of sleep costs US businesses a huge amount. An average of $100 billion is lost per year.

Here's what George Belenki, director of the Center for Sleep and Performance Studies at the University of Washington, had to say about it:

If your job is mental, you pay productivity for lack of sleep.

After that, a completely logical question arises: how much time do you need to sleep in order not to accumulate fatigue and reduce productivity?

Based on research data, we can say that this time is from 7 to 7.5 hours. In general, experts agreed that 95% of adults need 7 to 9 hours of sleep per night to be productive.

For most adults, it is better to sleep 8 hours a day, and for children, teenagers and the elderly - even more.

How sleep works: sleep and wake cycles

The quality of your sleep is determined by a process called the sleep-wake cycle.

There are two important points in this cycle:

• Non-REM sleep (also known as deep sleep).
• REM sleep (REM phase, rapid eye movement phase).

During slow-wave sleep, the body relaxes, breathing becomes calmer, blood pressure drops, and the brain becomes less sensitive to external stimuli, making it harder to wake up.

This phase is of great importance for the renewal and restoration of the body. During slow-wave sleep, growth hormones are produced in the pineal gland, which provide tissue growth and muscle repair.

Researchers also suggest that the immune system is restored during non-REM sleep. So the slow phase of sleep is especially important if you play sports. Some professional athletes, like Roger Federer or LeBron James, slept 11-12 hours a night.

Another example of the impact of sleep on physical performance is a study conducted on basketball players at Stanford University. During the study, the players slept at least 10 hours per night (as opposed to the 8 hours of sleep they were used to).

The experiment lasted five weeks, during which the researchers assessed the speed and accuracy of the players in comparison with their usual results.

It turned out that just two extra hours of sleep increased the number of successful throws by 9% and reduced the time to sprint 80 meters by 0.6 seconds. So, if you have heavy physical activity, the slow phase of sleep will help you recover.

REM sleep is just as important for the mind as slow sleep is for the body. Most of the time when you sleep, the brain is calm, but when the REM phase comes, it becomes active. This is the phase during which you dream and your brain redistributes information.

During the REM phase, the brain erases unnecessary information and improves memory by linking the experiences of the last 24 hours with previous experiences, facilitating learning and provoking the growth of neural connections.

At this time, the body temperature rises, blood pressure rises, and the heart beats faster. In addition to this, the body is moving. In general, REM sleep occurs three to five times a night for a short period of time.

A person cannot function normally without both phases of sleep. Sleep deprivation affects health: immunity goes down, consciousness becomes “foggy”, the risk of infectious diseases increases, blood pressure and the risk of heart disease increase. In addition, sleep deprivation threatens mental illness and reduces life expectancy.

The slow phase of sleep helps restore physical health, the fast phase - mental capabilities.

However, despite the great importance of sleep for the body, the quality and duration of sleep during life change.

Age-related changes in sleep

Based on research from Harvard Medical School, it can be said that as people age, it becomes increasingly difficult to fall asleep. This phenomenon is called sleep delay. And sleep efficiency - the percentage of time you spend in bed while sleeping - is also decreasing.

On average, 80-year-olds have 62% less long sleep than 20-year-olds. There are many factors that affect the aging of tissues, and if this phase of non-REM sleep is shortened, the aging process is even faster.

Healthy sleep is your best weapon against rapid aging.

How to recover from lack of sleep

Most adults need 8 hours of sleep to keep their performance at their best. Since older people have trouble sleeping, they can make up for the lack of nighttime sleep by taking a nap during the day.

In any case, if you understand that you need to take a nap, it is better to do it once in the middle of the day than to periodically fall asleep during the day and evening.

In general, the body recovers well after short-term sleep deprivation. For example, if you had a rough night where you managed to get 2-4 hours of sleep, the next night 9-10 hours of sleep will completely restore your body.

It's just that your body will spend more time in REM and NREM sleep to make up for the lack of sleep last night.

There is no need to plan how much time your body will spend in REM and non-REM sleep. It knows better how much sleep and how much sleep is needed for recovery, so you will not be able to control this process.

And remember that there is no substitute for sleep. If you are bound to stay awake longer today, make sure you sleep longer than usual the next night.

circadian rhythms

How are your sleep and wake cycles organized?

With the help of circadian rhythms. These are biological cycles of different processes that occur within 24 hours.

Here are a few key points of the 24-hour cycle:

6:00 a.m. - Cortisol levels rise to wake up your body

7:00 am - melatonin production stops;

9:00 - peak production of the sex hormone;

10:00 - peak of mental activity;

14:30 - the best level of coordination of movements;

15:30 - best reaction time;

17:00 - the best work of the cardiovascular system and muscle elasticity;

19:00 - the highest level of blood pressure and the highest body temperature;

21:00 - melatonin begins to be produced to prepare the body for sleep;

22:00 - The work of the digestive system calms down, as the body prepares for sleep;

2:00 - deepest sleep;

Of course, these are only approximate rhythms, since they are individual for each person and depend not only on daylight, but also on habits and other factors.

In general, circadian rhythms are influenced by three main factors: light, time, and melatonin.

Light

Light is one of the most significant factors that sets the circadian rhythm. Staying in bright light for about 30 minutes can reset your rhythms, no matter what time it is.

In general, when the sun rises and light enters your closed eyes, it signals the start of a new cycle.

Time

The time of day, your daily schedule, and the order in which you are used to performing different tasks all affect your sleep and wake cycles.

Melatonin

It is a hormone that causes drowsiness and controls body temperature. Melatonin production depends on a daily, predictable rhythm. Its amount increases at night and decreases when it becomes light.

How to sleep better

Here are a few rules for falling asleep quickly and sound sleep.

Avoid caffeine

If you have trouble sleeping, it's best to eliminate caffeine from your diet altogether. But if you can't turn on in the morning without a cup of coffee, at least don't drink it after dinner.

Quit smoking

In the experience of many people who quit or have already quit smoking, cigarettes have a bad effect on sleep. After you quit smoking, it will be easier to fall asleep, and the number of awakenings at night will decrease.

Use the bedroom only for sleep and sex

Remove the TV from the bedroom, do not bring a laptop and tablet. The ideal sleeping environment is a dark, cool, and quiet bedroom, so try to make it that way.

Exercises

Physical activity helps the body and brain shut down at night. This is especially true for older people. It has been proven that mobile, active older people sleep much better. However, at least three hours should pass between classes and sleep, so that the brain and body have time to calm down and prepare for sleep.

Temperature

Most people sleep better in a cool room. The ideal temperature in the bedroom is 18–21°C.

Sounds

A quiet room is ideal for a great night's sleep. But if you find it difficult to fall asleep in complete silence, you can turn on white noise.

No alcohol

Small (or very large) amounts of alcohol can help you fall asleep, but the quality of such sleep leaves much to be desired. During such sleep, the REM phase is reduced, so you do not have a good rest, even if you slept all night.

How to get ready for bed

Here's what to do to avoid insomnia.

Set a daily schedule

Our body loves systems. In essence, the circadian rhythm is your daily routine on a biological level. Go to sleep and wake up at the same time every day.

Get in the habit of turning off all electronics an hour or two before bed. Light from a computer, TV or smartphone delays the production of melatonin, which helps the body prepare for sleep.

In addition, working before bed increases brain activity and can increase stress levels, which is bad for sleep. Instead of checking your work email, read a paper book. This is a great way to get away from the screen and learn something interesting and useful.

Use relaxation techniques

Researchers claim that 50% of cases of insomnia are due to strong emotional experiences and stress. Find a way to reduce stress and you'll find it much easier to fall asleep.

Proven methods include journaling, breathing exercises, meditation, and exercise.

Don't miss the opportunity to take a nap

Afternoon naps help replenish sleep cycles. This is especially useful for those who cannot sleep well at night.

How to be more energetic in the morning

Drink a glass of water in the morning

Your body has gone 6 to 8 hours without water. Feeling sleepy in the morning (of course, if you slept enough) can be caused by a lack of moisture. So a glass of cool water may well refresh you.

Start your day in sunshine

Sunlight in the morning is especially important for the circadian rhythm. Light wakes up your brain and body so you don't even need your morning coffee during the sunny summer months. The main thing is to stay in the morning in the light.

Conclusion

So, the main idea of ​​this article is that nothing can replace sleep. If you quite consciously subject yourself to deprivation, you do not allow the brain to work to its fullest, and the body - to recover.

Lack of sleep is an obstacle between you, health and productivity. So sleep more.

All sleep is divided into two fundamentally different types - this is slow sleep and REM sleep. In turn, non-REM sleep is divided into 4 phases. It turns out that there are 5 phases of sleep in total.

slow sleep

It is also called the doze stage. It is characterized by thinking about and experiencing the problems that have arisen during the day. The brain, by inertia, tries to find a solution to the problems on which it worked while in the waking state. A person can see images that implement the solution to the 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 the third and fourth phases of sleep lies in the number of delta oscillations. But we will not go into such details.

It is 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 working capacity. In the fourth phase of sleep, a person is difficult to wake up. Cases of sleep talking or sleepwalking occur during this phase.
The first two phases are considered superficial non-REM sleep, and the second two are considered deep. Non-REM sleep is also called orthodox sleep or non-REM sleep.

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

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 accelerated movements of the eyeballs under closed eyelids - this is the first fundamental difference from non-REM sleep.

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

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

1. In the stage of REM sleep, the brain sorts out the received information.
2. The brain analyzes the environmental conditions in which the body is located and develops an adaptation strategy. An indirect confirmation of this judgment is the fact that in newborns, REM sleep is 50%, in adults - 20-25%, in the elderly - 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 remember a dream well only if you wake up in REM sleep.

Sequence of sleep stages

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

This changes the duration of different phases from cycle to cycle. In the first cycle, REM sleep is very short, more time is taken by deep slow sleep. But in the last cycles of deep sleep, there may not be at all. Usually one cycle is 90-100 minutes.

And now the most interesting. In what phase of sleep you wake up, your well-being depends. The most unsuitable for waking up is deep sleep. Waking up from a deep sleep, you will feel overwhelmed.

It is best to wake up after the end of the REM 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 that you wake up in the right phase.

I will give only one thought on this matter. As already mentioned, in the stage of deep sleep, a person is quite difficult to wake up. Therefore, if your sleep is interrupted in a natural way, and not by an alarm clock, then you will most likely 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 an appendix.

The following facts are cited in support of this assertion:

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

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

Experiments were conducted when people were completely deprived of REM sleep for two weeks. At the same time, their health status did not worsen in any way.

Two weeks is not that long, considering that some people can go so 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 process of sleep is a very little studied phenomenon. Somnologists in the future will have to find answers to many controversial questions.
Well, we need to take care of our sleep and lead a healthy lifestyle!

During sleep, a person periodically alternates two main phases: slow and fast sleep, and at the beginning of sleep, the duration of the slow phase prevails, and before waking up, the duration of REM sleep increases. Sleep begins with the first stage of non-REM sleep, which lasts 5-10 minutes. Then comes the 2nd stage, which lasts about 20 minutes. Another 30-45 minutes falls on the period of 3-4 stages. After that, the sleeper again returns to the 2nd stage of non-REM sleep, after which the first episode of REM sleep occurs, which has a short duration - about 5 minutes. This whole sequence is called a cycle. The first cycle has a duration of 90-100 minutes. Then the cycles are repeated, while the proportion of non-REM sleep decreases and the proportion of REM sleep (REM sleep) gradually increases, the last episode of which in some cases can reach 1 hour. On average, with a full healthy sleep, there are five complete cycles.

First: Restore the conditions that automatically trigger sleep in a patient suffering from cocaine.

• To do this, we need: to obtain adequate physiological conditions.
• Get an adequate sleeping environment.
• Achieve physical and cognitive deactivation.

Therefore, our detox team usually prescribes. Alcohol metabolism consumes a lot of water, so you need to avoid excess alcohol to avoid waking up thirsty in the middle of sleep. Control the indoor environment by ensuring that the room temperature is cool and pleasant, that there is no strong light, and that there is sufficient humidity. Make sure the bed is big enough so that the mattress and mattress are firm and comfortable enough so that clothing isn't skimpy, excessive, or annoying. Noise is an important factor that distorts sleep, so we must ensure that during sleep it is quiet and without noise. Jacobson Deep Muscle Relaxation: The Jacobson Relaxation Method is used in our cocaine detox clinics to promote sleep as it teaches us to reduce muscle tension and therefore promote physiological deactivation.

slow sleep

Non-REM sleep also has its stages.

First stage. The alpha rhythm decreases and low-amplitude slow theta and delta waves appear. Behavior: drowsiness with drowsy daydreams and dream-like hallucinations. At this stage, ideas may intuitively appear that contribute to the successful solution of a particular problem.

Now it can not be used as a sleeping pill; that is, to do exercises when you are awake, because the essential condition for rest is not fulfilled, which must be done endlessly, because in fact it becomes an attempt to sleep, and the effort does not lead to relaxation or sleep. This is why it is recommended to do relaxation exercises at other times of the day and for the sole purpose of learning to recognize when you are tense.

The importance of deep sleep for the body

Diaphragmatic Breathing: Breathing is also a good relaxation technique. Sleep is associated with deep, regular and abdominal breathing, which can lead to physiological deactivation. Thoughts and concerns for our cocaine detox team are a major component of insomnia. The following classes were defined: resolution of daily problems, care to stay awake, general problems, noises in the house, and other conditions in the room.

Second stage. At this stage, the so-called "sleep spindles" appear - the sigma rhythm, which is an accelerated alpha rhythm (12-14-20 Hz). With the advent of "sleepy spindles" there is a disconnection of consciousness; in the pauses between the spindles (and they occur approximately 2-5 times per minute), it is easy to wake a person up. Perceptual thresholds rise. The most sensitive analyzer is auditory (the mother wakes up to the cry of the child, each person wakes up to the naming of his name).

The problem with thought control is that it is ironic or paradoxical because there is a process of looking for alternative thoughts and the other is checking if it is achieved or if it fails and that causes the thought to increase its frequency. When we want to not think about something, we think about something else, and we understand it, but suddenly we realize that we have achieved it, and that we did not think about it, with which the thought becomes real again. The desire to stop thinking about something has been shown to increase the frequency of that thought.

Third stage. It is characterized by all the features of the second stage, including the presence of "sleep spindles", to which slow high-amplitude delta oscillations (2 Hz) are added.

4th stage of non-REM sleep, deep sleep. This is the deepest sleep. Delta oscillations predominate (2 Hz).

Video: Somnologist R. Buzunov about interesting facts about sleep

Create a series of pre-sleep routines that activate the conditioning that automatically leads to the calmness needed for sleep. For example: lock the door with the key, turn off the gas, brush your teeth, set the alarm, and complete all the tasks required for that moment of the night, always do them in the same order. Set a fixed time to get out of bed and go to bed. You should get up around the same time every morning, including weekends. If you think you have to get up later on weekends, do it no later than an hour later. Control physiological variables, stay up hungry, thirsty, want to urinate, etc. avoid drinking alcoholic beverages. Alcohol can be a short term remedy. At first it has a calming effect, but then it causes insomnia and restless sleep, superficial sleep, followed by nocturnal awakenings. Calculate the time it takes to fall asleep. If it takes five minutes or less, it's likely that you won't be able to sleep. Five to twenty minutes is fine. And if it takes longer, that means you're not ready to sleep yet. A hot bath is another way to unwind before bed. Warm water relaxes and creates a feeling of well-being. Take warm milk before bed. It releases tryptophan, which is the substance that induces sleep. Have a quiet lunch and do not lie down for two hours after dinner. Before going to bed, do not drink chocolate or large amounts of sugar. Avoid drinking excess liquids. If you wake up in the middle of the night, don't eat anything, or you may start waking up around the same time usually feeling hungry. Control the noise, light and temperature in the room. If you cannot sleep, get up and come back when you are asleep. When you get into bed, you should turn off the light in the room with the intention of falling asleep immediately. If you can't fall asleep at one time, about 10 minutes, get up and go to another room. Engage in quiet activity until you feel numb and at that time return to the bedroom to sleep. Make sure the bed is big enough so that the mattress and mattress are firm and comfortable enough so that the bedding isn't too thin, excessive, or annoying. Try natural remedies such as lemon balm, Roman chamomile, valerian, passionflower, lavender, passionflower, etc. don't go to bed until you sleep. Do not use the bedroom for activities other than sleeping. The only exception to this rule is sex. Don't use bedtime to think about your problems.

• Exercise regularly, but do it throughout the day.
• Avoid doing this hours before bed.
• A daily walk before dinner is recommended.

Stages 3 and 4 are often referred to as delta sleep. At this time, it is very difficult to wake a person; 80% of dreams occur, and it is at this stage that sleepwalking and nightmares are possible, but the person remembers almost none of this. The first four slow-wave stages of sleep normally occupy 75-80% of the total sleep period.

It is an active process involving multiple and complex physiological and behavioral mechanisms in various systems and regions of the central nervous system. In addition, this stage is also characterized as the stage in which dreams occur. The distribution of sleep stages at night can be altered by several factors such as: age, circadian rhythm, room temperature, drug intake, or certain diseases.

Sleep mode is attributed to several functions. The simplest hypothesis is that sleep is designed to restore the body's possible energy flow established during wakefulness. Do not use alcohol or coffee, some teas and soft drinks before bed. If you've had little sleep on previous nights, avoid sleeping during the day. Don't bring trouble to bed. Perform calm and relaxing activities in preparation for sleep. Be physically and mentally active.

• Have regular sleep and wake times.
• Go to bed just before bed.
• Maintain a proper sleep environment: clean, dark, no noise and comfort.
• Do not use sleeping pills without medical advice.

It is assumed that slow sleep is associated with the restoration of energy costs.

REM sleep

REM sleep (REM sleep, or REM sleep for short) is the fifth stage of sleep. EEG: rapid fluctuations in electrical activity, close in value to beta waves. This is similar to being awake. At the same time (and this is paradoxical!) in this stage, a person is completely immobile, due to a sharp drop in muscle tone. However, the eyeballs very often and periodically make quick movements under closed eyelids. There is a clear link between REM and dreams. If at this time you wake up the sleeping person, then in 90% of cases you can hear a story about a vivid dream.

An example is the African elephant, the largest land animal. In the wild, it sleeps an average of two hours a day and often goes nearly two days without sleep. The investigation is unprecedented for coming out of captivity. Researchers observed two African elephant matriarchs in Botswana's Chobe National Park for 35 days. They provided the elephants with a sleep sensor in the trunk and a collar that allowed them to identify their sleeping position.

In their natural habitat, elephants sleep only two hours a day, the least amount of sleep among mammals, says Paul Menger of the University of the Witwatersrand in South Africa. They don't have time to daydream, the researchers contacted. They remain awake for up to 46 hours, traveling long distances during these periods.

The phase of REM sleep from cycle to cycle lengthens, and the depth of sleep decreases. REM sleep is more difficult to interrupt than slow sleep, although it is REM sleep that is closer to the threshold of wakefulness. Interruption of REM sleep causes more severe mental disorders compared to non-REM sleep disorders. Part of the interrupted REM sleep should be replenished in the following cycles.

Predators constantly harass the elephants, who must always be on their guard. Another reason for several hours of sleep is the amount of food eaten. Herbivores that eat low-calorie foods need to spend more time chewing in order to consume energy from their food and not need as much time to digest. Not surprisingly, the giraffe, like the elephant, sleeps very little.

Already, the number of hours of sleep is universally decreasing among mammals, depending on the density of neurons per region of the cerebral cortex. The lower the density of neurons in the brain, the less the animal needs to sleep. Neurons grow, density per area falls, and animals sleep less. More time for feeding allows you to increase the growth of evolution.

It is assumed that REM sleep provides the functions of psychological protection, processing of information, its exchange between consciousness and subconsciousness.

Those who are blind from birth dream of sounds and sensations, they do not have REM.

How much a person needs to sleep is inextricably linked with such a concept as sleep phases. The phases of sleep in any person alternately alternate, replacing each other, and there should be a certain number of such alternations. Otherwise, the body will not receive all the necessary time to restore internal structures, as well as to structure the information received during the day.

Is it possible to sleep well?

Sleep-inducing metabolites accumulate in the waking brain and are produced by the neurons themselves. How long an animal should be awake depends on how long it takes for the critical concentration of sleep-inducing metabolites to accumulate. the lower the density of neurons under a certain cortical surface, the slower it must be the accumulation of metabolites, and the longer the animal must last in an active state, the neuroscientist says.

That's about 7 hours of sleep a day. But this is less than the average need for 8 hours of human sleep. They are the only omnivores on the list. The goat sleeps about 5 hours a day. More than sheep, they sleep about 4 hours. Cows spend almost all day chewing and walking. About 4 hours of sleep remain.

The phases of sleep must be completely fulfilled, thus forming a complete cycle of night rest. Moreover, depending on nature, a person can get enough sleep for more or less of such cycles.

Let us consider in more detail the phases of sleep themselves, which are the same for any person and can only vary slightly in time. And then we'll talk about the full cycles of these phases to find out how much a person needs to sleep in order to get enough sleep. Here, the difference between two single individuals can be radically different.

Ever seen a horse sleep? Yes, for one hour he tires and lies. And pack about 3 hours of sleep. The same number as the donkey. Some studies already show that the giraffe only sleeps about two hours a day. They were considered the animals that slept the least. The latest research from Botswana is now linked to the largest land mammal, the African elephant.

The Greeks were afraid of Morpheus, the god of dreams, because they believed that every night when he fell asleep, the deity could torment them by sending terrible nightmares. Science, however, can prove that sleep is a good teacher. The American scientist's findings are the result of a series of experiments presented last month at the third International Congress of the World Federation of Sleep Research Societies. The meeting, held in the German city of Dresden, brought together leading researchers from around the world. Every effort becomes a waste if the hours in the books are not accompanied by a good night's sleep.

Sleep phases

The sleep phases of any person are divided into 2 types:

• Phase of slow sleep;
• REM sleep phase.

The complete passage of all phases of sleep takes different people from 1 hour to 1.5 hours. Usually guided by the last digit, although it is not accurate. Each of us has his own total duration of sleep phases, which can vary slightly not only in different periods of life, but even during one night's sleep.

Phases of non-REM sleep

Non-REM sleep begins the moment you fall asleep and takes up three-quarters of your entire sleep cycle.

Slow-wave sleep begins with a process of drowsiness, which smoothly flows into superficial, moderate-deep and, finally, deep sleep. In total, the phase of slow sleep, as you can see, consists of 4 types of sleep.

It is very important that nothing interferes with sleep during the slow wave sleep phase. After all, it is during this phase that all the changes necessary for the health of the body occur:

• In mice, the energy spent per day is restored;
• There is a restoration at the cellular level of various structures of the body;
• The body builds protein structures - muscles, tissues of internal organs;
• Fat burning occurs (in case of proper nutrition during the day, especially in the evening);
• Necessary hormones are released, primarily growth hormone and melatonin;
• The body prepares for the next day.

If the phase of slow sleep is often disturbed, then such a ragged sleep leads to the fact that in the morning a person feels weak, physically weak, lacks energy and is weak. True, the cause of all these problems can be not only poor sleep conditions in the slow phase, but also a general lack of these slow phases of sleep, which will be discussed below.

Scientists believe that the maximum effectiveness of slow-wave sleep phases occurs before 4 am. At the same time, in each new cycle, the proportion of non-REM sleep phases gradually decreases, giving way to REM sleep phases.

After 4 a.m., slow-wave sleep phases almost do not appear. Therefore, if you feel a lack of strength and energy every morning, it may be because you go to bed late, and therefore, the body does not have enough time for all the slow phases of sleep to recover.

REM sleep phases

REM sleep occupies a relatively small fraction of the sleep cycle - only one quarter. But from this it does not lose its significance.

During REM sleep, the body:

1. Processes, sorts absolutely all the information received during the day;
2. Restores the energy of the nervous system;
3. Prepares memory and attention for further work during the new day.

After 4 a.m., almost all sleep time is devoted to the fast phase, which is associated with a quick transition to wakefulness. The organism has already prepared the physical body for work, and now it is preparing the mental sphere.

Sleep cycles. How much sleep do you need

Sleep cycles are related to sleep phases. The circle of slow-wave and REM sleep forms one sleep cycle. And the whole question is how many sleep cycles should be during a person's nightly rest.

Scientists agree that the average person needs 5 sleep cycles. That is why they usually talk about 7-8 hours of sleep needed to rest at night. 5 cycles of 1.5 hours just give 7.5 hours of sleep.

However, there are people who sleep little. For such people, only 4 phases of sleep are enough to restore the strength and structure of the body, as well as process all the information. As a result, 6 hours of sleep (or even less) is enough for such people.

There is another group of people who need to sleep for 6 cycles, which takes about 9 hours. And it is not at all necessary to consider such people couch potatoes. It's just that their bodies are built that way. If they miss at least one sleep cycle up to 1.5 hours long, then they will feel overwhelmed and lethargic all day.

The minimum allowable number of sleep cycles is 4 cycles (4-6 hours long, depending on the duration of one cycle), but on the condition that these 4 cycles are completed before 4 am. In this case, the body will receive the minimum necessary time to recover during the phases of slow sleep, and in the morning such a person will feel quite acceptable.

For a long time it was believed that during sleep, the body simply turns off and rests. Only thanks to research into the phenomenon of sleep, it became clear that the brain and life support systems are actively functioning during sleep and doing the necessary work during its appropriate periods. Yes, it is not homogeneous and consists of certain phases of sleep, each of which has its own characteristics and serves certain purposes. Understanding the phases of sleep (or stages of sleep) will help us see how important it is to follow the recommendations in order to achieve the most effective rest on the one hand, and the active functioning of our brain and body on the other.

Sleep phases and their characteristics

What is sleep phases What do they depend on and how are they determined? First of all, it should be noted that each phase of sleep is associated with a certain type of wave of electrical activity in the brain. There are two main phases of sleep:

• REM sleep(rapid sleep stage)
• deep sleep phase(sleep stage)

Deep sleep is divided into 3 types.

Usually, sleep begins with phase 1 deep sleep. Next comes the phase of deep sleep 2, followed by the phase of deep sleep 3. And only when all three phases of deep sleep pass through, a transition to the REM phase is possible. Consider each of the phases in more detail:

Deep sleep phase 1.

From this stage of slow sleep begins our journey. Our sleep in this phase of deep sleep is easily disturbed, we are awakened by any noise or other influence. During this phase of sleep, our muscles relax, heart rate and breathing slow down. There are slight eye movements under the eyelids.

Deep sleep phase 2.

This stage of sleep is characterized by our slow wave brain waves with occasional bursts of fast wave activity. Eye movements stop. In NREM stage 2, we spend about the first half of our night.

Deep sleep phase 3.

In sleep stage 3, the speed of the waves becomes even lower and the brain begins to reproduce almost only very slow waves (Delta waves). This is a very deep stage of non-REM sleep and it is not easy to wake up during it.

REM sleep phase.

This stage of sleep wedged periodically into phases 2 and 3 throughout the night. The first appearance of the REM stage begins about an hour and a half after we fell asleep. This stage is characterized by rapid movements of the eyes under the eyelids, intermittent, uneven breathing and heartbeat. The muscles of the arms and legs are periodically paralyzed. The phase of REM sleep is also different in that it is here that we see dreams. We spend about one-fifth of our entire night in REM sleep (the same amount as in deep phase 3).

The duration of a particular phase of sleep changes with age. For example, an infant spends up to 50% of all sleep time in REM sleep, while in an adult it is only 20%. In addition, the distribution of sleep phases can be influenced by both external conditions and the internal state of a person. You can’t write off the effects of medications either - this is how Prozac, quite popular in the USA, is able to prevent the full flow of the REM sleep phase. Drinking alcohol before bedtime also affects REM sleep, pushing it back in the overall cycle to a later time of occurrence.

Irregular and unregulated sleep has a negative impact on the orderly flow of all phases of sleep. The phases go astray, which means that the brain is not able to complete all the planned processes in order to maintain the healthy functioning of the whole organism.

Sleep structure

Now to the practical side. Since sleep has a cyclical structure, sleep phases are repeated throughout the night in the following order G1-G2-G3-G2-G1-B. This is one cycle. The average duration of the first cycle is somewhat shorter than the subsequent ones and ranges from 70 to 100 minutes, the second and then from 90 to 120 minutes. In many sources, you can find that the average value is taken as a cycle - 90 minutes. It is important to remember that 90 min. - this is an approximate figure, and when calculating the total sleep time (number of cycles per night), you must definitely focus on your well-being. You can read more about sleep recommendations. So the first recommendation is:

RECOMMENDATION 1: Total sleep should be a multiple of a full cycle (90 to 120 minutes)

However, our well-being, easy and pleasant awakening is connected not only with the number of hours allotted for sleep, but also with the phase in which the awakening occurs. If we follow the rule of multiples of the total sleep time per cycle (the duration of the first cycle varies from 70 to 100 minutes, the second and subsequent from 90 to 120 minutes), then we automatically comply with the conditions for awakening at the beginning of the sleep cycle. In other words, for good health and easy awakening, we must wake up at the end of REM sleep or at the beginning of the first stage of deep sleep.

RECOMMENDATION 2: Awakening should occur at the end of the sleep cycle (at the end of non-REM sleep or at the beginning of deep sleep phase 1)

But how to wake up at the end of the cycle? How to know that right now is the best moment to wake up, because we are sleeping? There are several options for solving this problem.

Wake-up time calculation.

1. Calculate the wake-up time in multiples of cycles of 90-120 minutes. Since there is a range here, we can try to first take it equal to 90 minutes and see how we feel at the moment of awakening. If there is discomfort, try a different cycle duration, for example, 100 minutes, etc. Do not forget that the cycle is when we have already fallen asleep. The time that we need to go to sleep (we have already gone to bed, but are still awake - the stage of falling asleep), we do not include in the cycle, but take into account "from above" (20 minutes falling asleep + 5 * 90 = 7 hours 50 minutes of sleep )
2. Go to bed for a long period of time (from a month) at the same time and get up without an alarm clock. Our body itself should begin to wake up at the most opportune moment)
3. Use special programs for tablets and smartphones. You run this program before you start sleeping and put your phone face down next to you on the pillow. The program analyzes your sleep during the night and determines the best moment to wake up from the time interval you set earlier. Programs are available for different platforms, one of the varieties of SleepTime.

Take a nap during the day.

Well, let's not forget about a short daytime nap, not very common in northern cultures, but very popular in hot countries. There is a lot of debate about whether daytime sleep is beneficial and what effect it has on the subsequent course of sleep phases during the night. Some of the latest research results were presented by Professor Tomohide Yamada from Tokyo (Dr Tomohide Yamada, University of Tokyo, Japan) at the annual conference of the European Association for the Study of Diabetes (European Association for the Study of Diabetes). According to research by a Japanese specialist, too much daytime sleep (60 minutes or more is considered to be) increases the risk of diabetes by 46%. The time recommended and harmless daytime sleep is, according to the result of the study, no more than 40 minutes.

Another study on a similar topic was conducted in China. The main goal was to identify how daytime sleep affects older people. The study involved 25,184 people (mean age 63.6 years). As a result of the study, it was found that prolonged daytime sleep (from 90 minutes or more) negatively affects primarily women and contributes to the development of metabolic syndrome.

So, we have recommendations that daytime sleep should not exceed 40-60 minutes. This is fully consistent with the knowledge of the functional features of sleep phases. If we allow up to 40 minutes of daytime rest, then our sleep does not have time to move into deep phases of sleep, which will make waking up more difficult and can cause a feeling of fatigue and “brokenness”.

RECOMMENDATION 3: Daytime naps should not exceed 40-60 minutes

Knowing what phases our sleep consists of and their functional significance is practical information that will help us organize sleep in the best possible way. Let's appreciate our body and help it please us with its performance, health and strength for many, many years.

The norm of sleep for an adult is 7-8 hours. However, each organism is individual, and therefore the rest time is calculated differently. For some, 4-6 hours is enough to fully restore their vitality, while for others, 9-10 hours of sleep will be optimal. Regardless of which regimen a particular person observes, he has a phase of superficial and deep sleep.

Phase change

When our night journey to the realm of Morpheus begins, we fall into a deep sleep. It lasts approximately 60 minutes, followed by REM sleep. A full cycle, starting from the slow phase and ending with the fast one, takes approximately 90-120 minutes for an adult.

During the night, from 4 to 6 cycles pass, depending on the biorhythms of people. In the first cycle, deep sleep lasts the longest, then its duration decreases. The closer to awakening, the more time we spend in paradoxical sleep, during which the brain actively processes and sorts all the information we have received during the day. In the last cycle, it can take up to an hour.

Stages of the slow phase

Slow-wave sleep is also called orthodox or deep sleep. It is in it that we need to immerse ourselves at the very beginning of the rest in order to fully restore our vital functions. This phase, unlike the fast one, is divided into main stages:

1. Drowsiness - at this time we are just starting to fall asleep, our brain is still actively working, therefore we see dreams, they can be intertwined with reality, it is often at this stage that a person can find answers to questions that remained unresolved during the day.
2. Falling asleep is the stage at which our consciousness begins to turn off, but the brain is still sensitive to external stimuli, it is very important that nothing disturbs a person at this time, even the slightest noise easily wakes him up.
3. Deep sleep is the time when all functions in our body smoothly fade, the body relaxes, but weak electrical impulses still pass through the brain.
4. Delta sleep is the stage of the deepest sleep, when we are most relaxed, at which time the brain stops responding to external stimuli, the body temperature becomes the lowest, blood circulation and respiratory rate decrease.

The Importance of Slow Sleep

Scientists became seriously interested in the study of sleep in the 70s of the last century. In the course of various experiments on volunteers, it was found that depending on the duration of slow sleep, mental and physical indicators change in people.

The test took place at Stanford University and involved football students. If orthodox sleep lasted longer than usual, then endurance and productivity increased in athletes.

It is also known that athletes sleep not for 7-8, but for 11-12 hours a day.

What is the reason for this amount of sleep? The thing is that it is the slow phase that accounts for the process of restoring all the cells of the body. In the pineal gland at this time, growth hormone is produced, which triggers catabolism. This means that protein compounds are not broken down, as during daytime anabolism, but, on the contrary, are synthesized from amino acids. During falling asleep and when immersed in delta sleep, tissues and organs self-repair.

Scientists have also found that if sleep is deep and has the right duration, the immune system works much better. If we do not rest normally at night, then the protective functions of the body will decrease, and we will become susceptible to infectious and inflammatory diseases.

Youth also depends on how well we sleep - if the slow phase does not last as many hours as necessary, the aging process will take place at an accelerated pace.

The effect of deep sleep on intelligence

Scientists have been able to prove that slow sleep affects not only physical endurance, but also the mental abilities of a person. During the experiment, the subjects were given lists of a variety of words, completely unrelated to each other, before going to bed, and asked to remember them. It turned out that people who slept more in the delta stage performed better - they were able to remember more words than those who had shorter deep sleep.

Studies have also proven that artificially depriving a person of a deep sleep phase is equivalent to a sleepless night. If the fast phase tends to be compensated in the following nights, then it is impossible to “sleep” the slow one.

Symptoms such as deterioration in concentration, memory loss, decreased ability to work and other signs of insomnia are also observed if a person does not spend as much time in the orthodox phase as he needs.

No matter how many hours a person sleeps, the slow phase always "opens" his rest. It is very different from REM sleep and has its own characteristics. For example, scientists have proven that, under certain conditions, delta sleep can last longer than usual. This happens if a person is rapidly losing weight, he has a hyperfunction of the thyroid gland (thyrotoxicosis), or the day before he spent a lot of energy on physical work.

A curious fact is that it is in deep sleep that such disorders as sleepwalking, enuresis, and sleep-talking begin to be expressed; a person sees nightmares.

If at this time the sleeping person is awakened, he will not remember anything about his dreams or actions, he will be disoriented in time and space. This condition is associated with a slowdown in all processes in the body, which occurs during delta sleep.

Summing up

Each person needs to sleep as much time as is required for the full recovery of the body.

Deep sleep has many useful functions, it is simply necessary for normal physical and intellectual activity.

Those who want to increase its duration should play sports during the day, and in the evening solve logic puzzles, solve crossword puzzles, or train the brain in some other way. Moderate activity during the entire period of wakefulness will help you fall asleep quickly and have a good rest at night.