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

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 you feel fresh and alert, even if in fact this 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 past 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 completing 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, 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. Basically, 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.

Scientists tirelessly repeat that sleep is the key to a good state throughout the day and health in general. Lack of sleep is fraught not only with diseases, but also with neuroses and other disorders of the nervous system. So now let's look at why sleep is so important. Sleep norms for different ages - this will be discussed further.

A few words about healthy sleep

No one will argue with the fact that a person needs healthy sleep. So, it must be continuous and strong. Otherwise, the body does not rest completely, but partially. And all systems and organs are in an active state, which is not good for a person. What is healthy sleep?

1. This is a night's rest, which is enclosed in a certain framework. So, it is best to go to bed at 9-10 pm. This time should be the same from day to day.
2. An hour before bedtime, the situation in the house should be calm. Stress and excitement should be avoided.
3. Before going to bed, you need to stop eating. The maximum that you can afford is to drink a glass of kefir half an hour before going to bed.
4. What else is needed to make sleep useful? Sleep norms - this should also be closely monitored. After all, if you do not rest enough hours at night, you can significantly harm your health.

Children under the first year of life

How much does it take to feel normal? The question does not have a clear answer. After all, it all depends on age. Initially, you need to understand what is the norm of the baby?

First two months. At this time, the baby's nighttime sleep is the same as that of an adult, and averages 8-9 hours. However, at the same time, the baby also sleeps during the day, 3-4 times for a couple of hours. Generally speaking, a newborn should sleep between 15 and 18 hours in total.

Baby 3-6 months. Night sleep increases, but the number of daytime rests may decrease. In total, the baby should also stay in the arms of Morpheus for about 15-17 hours.

Baby from six months to a year of life. Gradually, the child needs less and less time for daytime sleep, the hours of wakefulness increase. Night sleep becomes better, because the baby gets tired during the day. During the day, the baby can sleep 2-3 times for 2 hours, at night - an average of 10 hours. In total, the baby should rest half the time of the day.

preschoolers

What is the norm of hours of sleep for a child? In this case, there are also certain differences.

Toddlers up to three years old. If we talk about children under the age of three, then for such children, on average, daytime sleep takes 2.5-3 hours, nighttime - 10-12. It all depends on the child himself, his character, temperament, the needs of the body. There are babies who switch to a one-time daytime sleep per year, and some need two - several hours each. In total, the baby should rest 13-14 hours.

Children from 3 to 6 years old. With kids of kindergarten age, things are also quite simple. If the baby goes to a preschool educational institution, there he will definitely sleep during the day for about 1.5-2 hours. An average of 10 hours of sleep a night is allotted. At the same time, it should be noted that, if necessary, the child can do without daytime rest. But this should not be the usual state of affairs.

Pupils

Sleep is also important for students. Sleep norms, again, vary, depending on the age of the child. If we talk about children of elementary school, then the night rest for them should be about 10 hours. Daytime sleep is no longer needed. But at first, the child may want to take a nap for an hour and you should not refuse the baby. After all, adjusting to a new mode of life is not so easy. If we talk about older schoolchildren, then night sleep for such children should be 8-9 hours. It is important to remember that you need to go for a night's rest at 9-10 pm. Then it will only benefit human health, and biorhythms will not be disturbed.

Adults

What is the norm of sleep for an adult? So, for health, people need to sleep an average of 7-8 hours. It all depends on the needs of the body. It is important to note that not only lack of sleep, but also too long sleep is harmful. In both cases, the result can be overwork, aggressiveness, hormonal failure, and problems in the functioning of the nervous system can also occur.

About sleep phases

Considering sleep, sleep norms, it is also necessary to talk about the importance of taking into account its special phases. Much also depends on their alternation. So, in general, there are two phases of healthy sleep:

• Quick sleep. At this time, the human brain is working, you can see various dreams.
• Slow. This is the same sound sleep, when the human body relaxes and rests as much as possible.

At the same time, it is also important to take into account the fact that the phase of slow sleep, in turn, is also divided into several levels:

1. Dormancy period. Here the person gradually relaxes, the brain is still very active and reacts to external stimuli.
2. The period of immersion in sleep. This stage is very important, at this time a person should be in a state of calm. By interrupting this period of sleep, people were even tortured. That is, if a person is awakened during this period, over time the nervous system will be so depleted that a failure may occur, fraught with irreversible nervous disorders.
3. Deep dream. The norm is not set here, it all depends on the work of the previous stages. This is the very tonic period when a person has the highest quality rest, and the body gains strength and energy. At this time, it is very difficult to wake the sleeping person.

In order for the body to feel great, the slow-wave sleep phase should take about 75% of the time, fast - 25%. During the night, a person can enter the phase of slow sleep twice, which will alternate with the phase of REM sleep.

Good rest is one of the main components of human health. For the formation, development, normal functioning of the body, ideal conditions are created during sleep. Only during this period useful hormones are produced, amino acids are synthesized. There is also improvement, systematization of brain activity, unloading of the nervous system.

To understand the ongoing processes, one should study what slow and fast sleep is, what are the differences between these structural units and determine their importance for people. These parameters are well compared according to the indications from the comparative tables.

The psychophysical processes that take place during sleep divide it into phases. At this time, there is a different activity of the brain, regeneration of certain organs and systems takes place.

REM sleep and slow sleep have a certain relationship. It changes from one cycle to the next. The constant interruption of one of the components has negative consequences.

Phase components of sleep and their sequence

Sleep is a certain structure, it includes several cycles that appear 4-5 times a night. Each one is approximately 1.5 hours long. This form contains the phases of non-REM and REM sleep.

An adult's rest begins with a nap, which is the initial structural unit of the slow period. Then three more components pass in turn. Then there is a short interval. The duration changes every cycle.

Features of slow sleep

The slow period lasts three-quarters of the duration of the rest. After falling asleep, it has the greatest length, gradually decreasing in the morning.

For a long rest, 4-5 periods are included in the cycles, this is the optimal value. It starts the process of falling asleep. In the third phase, bouts of sleepwalking may occur.

Structure

This phase is structured by periods. All of them are of great importance for a person. Each has its own characteristics, features, functions change in the process.

• nap;
• sleep spindles;
• delta sleep;
• deep delta sleep.

The first period is characterized by slow eye movement, a decrease in temperature occurs, the pulse becomes less frequent, stabilization of nervous activity occurs. It is at this moment that the solution to the problem that appeared during the day can come, the missing link in the semantic chain will be filled. Waking up is very easy.

In the second interval, consciousness begins to turn off, a person sinks deeper into drowsiness. The pulse is rare, muscle relaxation occurs.

During the third stage, the heart begins to contract more often, more superficial respiratory oscillations occur. The blood flow to the tissues is activated, the movement of the eyes is very slow.

The last period is characterized by the greatest immersion. At such a moment, it is very difficult for people to wake up, they get up not rested, it is hard to get involved in the environment, dreams are not stored in memory. All body functions are significantly slowed down.

signs

To understand that a person is in a phase of slow sleep, it will turn out if we compare the characteristic indicators: breathing, which becomes rare, shallow, often arrhythmic, the movement of the eyeballs first slows down, then completely disappears.

The heart rate slows down, the body temperature drops. By this period, the muscles relax, the limbs do not move, and there is no physical activity.

Meaning

When you are in a slow sleep, the restoration of internal organs occurs. During this time, growth hormone is released, this is especially important for children. They develop, improve all systems for such a period.

It's important to know! During this period, the substances necessary for the normal functioning of the body accumulate, amino acids are synthesized. This type of sleep is responsible for physiological rest.

REM sleep contradictions

REM sleep is also called paradoxical because of the inconsistencies between its various manifestations and internal processes. During the period of such rest, brain activity is very active, it can be even higher than during wakefulness, but at this time the person is in the process of dozing.

Muscle tone is significantly reduced, but the stage is characterized by the movement of the eyeballs, twitching of the limbs. If for some reason such a rest takes a long time, upon awakening there is a feeling of weakness, fragments of dreams are spinning in the head.

Manifestations

The fact that a person is in REM sleep can be seen without the help of devices. There are a number of specific manifestations. These include:

Body temperature rises, heart rate increases. The brain starts active. At this interval of rest, a combination occurs, a comparison of genetic information with the acquired one.

The value of the fast phase

During the period of fast rest, the nervous system is activated. All acquired knowledge, information, relationships, actions are processed and analyzed. Serotonin, the happy hormone, is produced.

During this period, the formation of the most important mental functions in children takes place. Insufficient duration of such rest can mean the imminent appearance of problems with consciousness. Programs for the future behavior of a person are created, answers are formulated to questions that cannot be found while awake.

dreams

Dreams that come to a person in this phase are the most vivid and memorable. They are colored emotionally, dynamically. External stimuli can be intricately woven into the plot of the vision.

Visions are transformed into different symbols, images, everyday reality. In the paradoxical phase, usually a person realizes that events are not happening in reality.

Awakening in different phases: differences

The structure of sleep is heterogeneous. All phases are distinguished by different brain activity, psychophysical activity, regeneration of certain human systems.

It's important to know! The incompleteness of the processes causes a complex transition to wakefulness in non-REM sleep. With a quick rise, it is easy, the beginning of vigorous activity occurs without problems. But the constant interruption of rest in this phase has a negative effect on the psyche.

Table: comparative characteristics of sleep phases

The parameters characterizing fast and slow sleep are shown in a comparative table. This is the main data that helps to recognize the rest period. From one cycle to the next, the duration of the first becomes shorter, the paradoxical lengthens.

Indicators	slow phase	fast phase
Number of stages	4	1
Sleep depth	deep	surface
Having dreams	quiet, hard to remember	bright, emotional, stored in memory
eye movement	no or very slow	fast
Muscle tone	slightly reduced	sharply weakened
Breath	rare, stable	arrhythmic
heartbeat	slowed down	accelerated
Body temperature	lowered	increased
Duration	75-80% rest	20-25% of sleep duration

Sleep research: interesting facts

The paradox of time perception is often encountered in relation to sleep. There are times when it seems only closed his eyes, and several hours have already passed. The opposite also happens: it seems that you slept all night, and 30 minutes have passed.

It has been proven that the brain analyzes sounds that are heard, sorts them, and can weave them into a dream. At the same time, in some phases, people can wake up if they are called by name in a whisper. The greater the biological age of a person, the shorter the duration of the paradoxical stage. In infants, it exceeds the slow one.

A person spends a third of his life in sleep. If you sleep less than a quarter of the day for two weeks, the state of the body will correspond to being intoxicated. Memory will worsen, concentration of attention, reaction will suffer, there will be a problem with coordination. But many geniuses over a long period of time practiced polyphasic rest, the total duration of which was no more than half the norm. At the same time, they felt cheerful, their efficiency improved, discoveries were made.

Dreams are seen by absolutely all people, but almost all of them are forgotten. Animals also dream. Not so long ago, most of humanity saw black and white dreams, and now 85% of men and women are viewing vivid stories. The explanation for this is the creation of color television broadcasting.

Blind people are also not deprived of dreams. If blindness is acquired, then the pictures make up what was seen earlier. With congenital absence of vision, vision consists of sounds, smells, sensations. They do not have such a phenomenon as rapidly moving eyes under the eyelids. These people are much more likely to have nightmares.

The longest period of wakefulness of a healthy person was a time period of 11 days that an American schoolboy did not sleep. After a head injury and brain damage, a soldier from Hungary did not fall into a nap for 40 years. At the same time, he felt cheerful, did not experience fatigue, discomfort.

It's important to know! Few girls who dream of a slim figure know the following fact. Regular lack of sleep leads to weight gain. One of the important conditions for losing weight is sufficient sleep.

Women's deep rest is often 20 minutes longer than men's, but the latter sleep more restlessly, waking up more often. The weaker sex at the same time complains more about sleep disturbances, sleeps worse. Ladies are more prone to emotionally strong visions, nightmares.

Conclusion

You can not make a choice which sleep is better fast or slow. Both of these components must be present in a person’s rest necessarily and in the correct percentage.

(REM) sleep has become so engrossed in the study of its paradoxes that no attention has been paid to the slow phase of sleep. Slow-wave sleep was perceived as a natural backdrop for paradoxical sleep.

However, this phase itself declared itself and made us think about the role of slow sleep in the vital processes of the human body.

During another experiment on deprivation for several nights of pre-morning REM sleep, the experimenters were surprised that the deepest stage of non-REM sleep, delta sleep, wants to take revenge on the recovery night.

Means, slow-wave sleep and fast sleep are inseparable and are extensions of each other:

• the synthesis of norepinephrine, a mediator of paradoxical sleep, occurs in non-REM sleep;
• when the raphe nuclei of the brainstem containing serotonin are destroyed, both stages of sleep are disturbed.

Having many differences, they belong to a single balanced system, they are connected by chemical, physiological, functional and mental processes..

Drowsiness with its rhythm resembles REM sleep. and is often filled with half-thoughts, and occasionally with real dreams.

two or three nights spent to the accompaniment of sound awakenings reduce physical and mental performance, give a feeling of fatigue, and slow down the speed of reactions.

This result speaks to the dominant role of delta sleep for physical and emotional recovery.

At first glance, the activity of the galvanic skin processes and the nightmares that occur during this stage do not show the accumulation, but the consumption of energy.

However, recovery processes are hidden behind the external picture of energy consumption. They explain the revival of vegetatives, it goes in a fast dream.

A deep mental work takes place, in which (as in wakefulness) scouts of the mind take part - emotions that give the first assessment, not yet realized, to any impression, any thought or memory that comes to mind.

Where there are emotions, GSR is always present.

The effect of additional physical activity on non-REM sleep

Young men far from sports, engaged in mental work, exercised on a bicycle ergometer for 120 minutes. Daily loads had almost no effect on the structure of night sleep. Evening loads had a noticeable effect.

Many have heard that sleep consists of successive phases and stages. Some people know that some phases are easier to wake up than others, so ideally, awakening should be adjusted to certain stages of sleep. Someone will say that dreams occur only in one phase (a small spoiler - this is actually not the case, see below). In this article, we propose to delve into these and other issues related to different periods of sleep, and consider, what are the phases what is their characteristic and duration, how many phases do you need to sleep, and how to independently calculate sleep by phases. In addition, in the last part of the text, we will consider how some so-called rational sleep patterns are evaluated in terms of phases and stages.

Phases of human sleep: a preface

Dreams seem like such a mundane thing, and yet this is one of those areas that still holds many mysteries. In particular, while there is no consensus among scientists even as to whether we see stages and phases of human sleep can be considered fully studied, including because they are easier to study using various instruments. The main sources are colored dreams or black and white. data for scientists - the activity of the brain in general and its lobes in particular (shown on the electroencephalogram - EEG), the movements of the eyeballs and the muscles of the back of the head. These and a number of other indicators make it possible to draw up a more or less clear picture of the cycles of sleep phases.

In general, we propose not to delve into the terms and methods of somnology (the science of sleep), but to consider the phases of sleep at a more practical level: to understand how many phases stand out, to analyze their main features and what distinguishes the phases from each other. This knowledge will help answer the questions in which phase it is easier to wake up, how long healthy sleep should last, etc. But first let's do a few remarks:

• phases and stages are considered with examples adults(with age, the ratio and duration of the phases change);
• for simplicity and uniformity, sleep periods will be shown using examples of those who goes to bed in the evening or at the beginning of the night, and not in the morning and does not work at night;
• we only consider physiological sleep- medical, hypnotic, etc. in this material are not taken into account;
• we will focus on those who have the happiness of sleeping enough hours for your body and is not forced, for example, to run to the first pair after writing a term paper at night.

So, what should be the normal sleep of an average healthy person in such conditions?

In general, experts divide sleep into two phases:

• slow sleep, he is orthodox, or NREM sleep. The name NREM comes from the English Not Rapid Eye Movement and reflects the fact that this phase is not characterized by rapid eye movements.
• REM sleep, he is paradoxical, or REM sleep(that is, rapid eye movements are present). The name "paradoxical" is due to the fact that during this phase of sleep, complete muscle relaxation and high brain activity are combined. It turns out that during this period the brain works almost the same as during wakefulness, but at the same time it does not process the information received from the senses, and does not give orders to the body how to respond to this information.

The NREM + REM cycle lasts about 1.5-2 hours(more details below), and during the night these phases sequentially replace each other. Average 3/4 cycle accounts for slow-wave sleep and, accordingly, about a quarter- to fast.

At the same time, a number of stages are distinguished in slow sleep:

1. nap- transition from wakefulness to sleep;
2. light sleep;
3. moderately deep sleep;
4. deep dream- It is at this stage that sleep is the strongest.

Stages 3 and 4 are collectively referred to as − delta sleep, which is associated with the presence of specific delta waves on the EEG.

Scheme of the night cycle by phases and stages of sleep

In terms of sleep cycles, our night goes like this:

• First comes stage 1 slow-wave sleep, that is, we move from wakefulness to sleep through drowsiness.
• Next, we successively go through stages 2, 3 and 4. Then we move in the reverse order - from delta sleep to light (4 - 3 - 2).
• After stage 2 comes the phase REM sleep. Due to the fact that it is activated last in the cycle - after all the other stages have passed - it is sometimes called phase 5 or stage 5, which, strictly speaking, is not entirely accurate, because REM sleep is completely different compared to slow sleep. .
• Then we return to stage 2, and then again we plunge into delta sleep, then light, then fast, then light again ... And so the change of phases and stages goes in a circle. Another option is to wake up after REM sleep.

The duration of the phases and stages of sleep

As we said above, the entire sleep cycle (non-REM and REM sleep) takes an average of about 1.5 hours to 2 hours. At the same time, the duration of phases and stages and their ratio within one cycle changes with the course of the night. Consider how the phases are distributed on average and how long each of them lasts.

Thus, in the first cycle, full-fledged deep sleep (stage 4) occurs approximately 40-50 minutes after sleep, and fast In 1.5 hours. Based on the average need for sleep, we find that in a normal state a person needs to sleep 3-6 cycles per night - depending on their duration and on his need for sleep. In turn, this need is very different: some need 4 hours, for some the norm may exceed 10 hours.

What phase is better to wake up and how to calculate it

As known, waking up most easily in REM sleep, in second place - the stage of the lung. Knowing the sequence of different periods, you can guess the optimal time to wake up. On the other hand, it must be taken into account that the duration of the phases is not the same for different people, in addition, the need for one or another “type” of sleep varies depending on the state. For example, if you are tired, sick, or recovering from an illness, non-REM sleep can take longer.

Of course, to make it easier for yourself to wake up, you can buy various gadgets that read the characteristic features of the phases (more details below) and wake up
you at the right time. But you can learn how to wake up in the REM sleep phase on your own - first of all you need to experiment. For example, take 2 hours as a sleep phase, calculate what time you need to go to bed / wake up in order to withstand an integer number of cycles. For example, if you have to get up at 8 am, the phase multiple would be 6 am, 4 am, 2 am, midnight, and so on. When calculating the time, keep in mind that it will take you a little more time to fall asleep. As we said, stage 1 usually takes 5-15 minutes. That is, to get up at 8, you need to go to bed at 1:45 or 23:45.

Try to stick to this schedule for a while and see if you can wake up in REM sleep. If not, "play" with the boundaries - make the calculation based on 1 hour 50 minutes or 1 hour 40 minutes. Thus, you can find exactly your duration of the night cycle and build on it in the future. It is best to conduct experiments when you are in a normal physical and emotional state and had more or less normal sleep on the eve of the experiments.

We also hint that by “go to bed” we mean exactly go to bed, and not “go to bed with a smartphone in an embrace and chat in instant messengers for another hour.” We also note that the calculation of sleep phases will not give you vigor if you have been sleeping only one cycle per night for a week. Phase adjustment is a tool for easier awakening, but it will not free you from the need to fully sleep.

Phases of sleep and dreaming

What happens to us in different phases of sleep

One of the main differences between phases is different brain activity, which can be visually traced in the waves on the EEG, however, the physiology of sleep phases is characterized not only by this. Another difference between fast and slow is reflected in the English names REM and NREM - the presence and absence of rapid eye movements. In general, determining the phase of sleep by eye, without taking into account instruments and measuring various indicators, is quite problematic. We can only say that if a person moves his eyes, limbs, etc., most likely, we are talking about REM sleep. And what can be registered on various devices? Here are some interesting facts.

Features of slow sleep

To plunge into the first stage of non-REM sleep (drowsiness), the brain produces special substances that block its activity, cause lethargy, and also affect other body systems, including slow down metabolism. In stages 2-4, especially during delta sleep, metabolism also slows down.

To say that during slow sleep, in principle, no eye movements, not quite right - they are in stages 1 (drowsiness) and
2 (light sleep), but specifically slow; in English terminology, they are called slow rolling eye movement (SREM). In turn, during delta sleep there are not even such movements, but it is in this phase that people walk or talk in their sleep, and also perform other uncontrolled actions, if they are peculiar to it.

REM sleep traits

One of the main features of REM sleep is most vivid dreams. By the words "the most vivid" we mean that almost all the dreams that we remember after waking up are from this phase. It is believed that REM sleep, in turn, is responsible for processing the information received during the day, internal work on emotions, etc. But so far, scientists cannot say for sure how exactly what happens during REM sleep and what mechanisms are involved in this.

As we have already noted, visual fast sleep can be recognized by the movements of the eyeballs, by sometimes stuttering breathing, hand movements, etc. Also, this phase is characterized by changes in body temperature and heart rate: they can rise or fall within the same stage.

It's interesting that brain activity during REM sleep so high that scientists for a long time could not notice the difference on the EEG between this phase of sleep and wakefulness. To date, however, several important differences have been found.

Interesting Features Associated with Sleep Phases

Each phase is characterized a distorted view of time. Probably, everyone is familiar with situations when you close your eyes for a minute - and 5 hours are gone. The reverse is also true: it seemed that the whole night had already passed and many dreams had been dreamed, but in fact only 20 minutes had passed.

Some believe that during sleep a person is completely disconnected from reality, however, this is not actually the case. Many brain signals are indeed not properly processed, especially during
delta sleep, but during fast and light sleep, sounds become the main source of information. For example, we are not always awakened by noise, but a person can wake up from the fact that someone even softly calls his name. Also, during REM sleep, sounds can be embedded in a dream and become part of it. This means that the brain processes sounds during sleep and decides what to pay attention to and how to do it.

Children have more REM sleep than adults, and older adults have even less. That is the older we get, the shorter the paradoxical phase sleep and longer orthodox. Interestingly, REM sleep is observed even in children in the womb. Scientists say that in the early stages of life (including before birth), REM sleep is very important for the formation of the central nervous system.

Research shows that the brain may not be submerged entirely in the same phase, which is especially characteristic of delta sleep. Although most of the brain, as a rule, is at the same stage.

The importance of sleep phases for the body: a small warning

It is impossible to say which sleep is better or more useful - fast or slow. Both phases are needed for proper rest and recovery. body, both physiologically and mentally. In this regard, questions arise about sleep patterns in which there is no full-fledged cycle. Surely, many have heard of schemes that suggest that a person sleeps not once a day for 6-8 hours, but several times during the day.
Some of these schemes look quite harmless, but the benefits of others are seriously questionable.

In particular, there is information on the Internet about a supposedly very effective schedule when you need to sleep 6 times for 20 minutes or 4 times for 30 minutes. Based on a typical sleep cycle, these time intervals are very short, and in 20-30 minutes a person will not have time to go beyond stages 2-3, that is, deep and REM sleep is not in principle. Meanwhile, the most important processes for our body occur precisely at these stages. It is possible that people who are described as successfully using such schemes have very compressed sleep cycles, but there is a good chance that reality is simply embellished for the sake of an impressive story.

Of course, for some time the body of an average person will function for 20 minutes 6 times a day. It may even seem to him that he has become more efficient in spending time, but the benefits of these schemes for the body in this case raise questions. Systemic lack of sleep affects both the mental and physical state and leads to various unpleasant consequences. Without denying the benefits and effectiveness of other rational sleep patterns, we urge you to consult with your doctor and be very wary of options that do not include at least a few full cycles per day.