How sleep phases affect human health and what is the secret of good sleep

Sleep is an unusual condition of the body, which is sometimes compared to death. In fact, they have little in common. In contrast to the complete destruction of the body, rest, by contrast, contributes to long life. It updates all systems, helps to restore physical, moral strength.

In this case, sleep is not something homogeneous in structure. There are different phases, each of which performs a specific function and lasts quite a certain amount of time. Everyone knows that deep sleep is helpful. But when it comes, how it affects the body – only a few know about it.

Sleep function

Awake, people and animals spend a lot of energy. Sleep is one of the body’s self-regulation mechanisms that helps restore this energy. Its main functions are:

  • rest of the ;
  • recovery of physical strength;
  • “Reloading” of the brain (at night the information received during the day is processed, systematized and stored);
  • cleansing the body of toxic substances (not without reason, sick people, doctors recommend more sleep);
  • immunity restoration;
  • cell renewal;
  • opportunity to use the body to wait out the period of darkness.

Long-lasting deep sleep helps improve memory, burn excess fat, overcome stress and illness.

What is the difference between the phases of deep and fast sleep?

During different phases in the brain, information is processed differently. Fast and slow sleep helps to remember the events, to plan their future, but each in its own way.

The slow sleep phase “includes” memory resources. When a person sinks into a deep sleep (he is slow), all the information received during the day begins to be systematized and “laid out on the shelves”. This phase improves memorization, logical thinking.

The REM sleep phase is the real “workshop” of the future. With its help, the brain models the possible development of the expected events. No wonder they say that I had a “prophetic” dream. By itself, he is certainly not prophetic. It’s just that during the period of fast sleep a person had models of the future, one of which he realized when he woke up. All this happens on a subconscious or intuitive level. However, the rest of a person is not limited to these two phases. It has a more complex structure.

Phases and stages

There are 4 main stages of sleep:

  1. Falling asleep
  2. Slow sleep.
  3. Fast.
  4. Awakening.

Each phase is characterized by a certain duration and related physiological processes only.

Falling asleep

1st phase – falling asleep. While a person plunges into sleep, his sensitivity of the sensory systems and heart rate decreases, his consciousness gradually “switches off”. Even the glands begin to work less actively. This can be seen by burning eyes, dry mouth. The approach of the sleep phase is easily determined by intrusive yawning.

Such sensations are often noticed in the night owls, who stayed late until late in reading or watching TV. If all the signs described are there, it’s time to let the body rest. The sleep phase is the shortest. It usually lasts about 10 minutes. Then begins a slow dream, divided, in turn, into several stages.

What is slow sleep?

Rest is called slow, in which brain activity remains in the low-amplitude range. Scientists fix this with EEG (electroencephalogram).

All the phases of a person’s sleep in time take a different duration. If 10 minutes is enough for falling asleep, then for the slow sleep phase it takes from 80 minutes to 1.5 hours. Duration depends on the individual characteristics of human physiology, as well as on its mode of rest. Unlike fast sleep, the slow phase is divided into several stages.


Slow-wave (he is slow) sleep has the most complex structure. It is divided into the following 3 phases (or cycles):

Light sleep phase

It occurs immediately after falling asleep and lasts about half the time of the slow. At this stage, the human muscles are completely relaxed, breathing becomes calm, deep. The body temperature drops a little, heart rate slows down. The brain goes completely into rest mode.

The EEG captures the sleep spindles at this time. So scientists called theta waves, folding in a sigma rhythm (12-14-20 Hz). Such a work of the brain indicates a complete disabling of consciousness.

The eyes do not move at this time. He is completely relaxed, but he is not sleeping very deeply yet. It is easy to wake a person up during a light sleep. Loud sounds or physical impact are able to return him to the waking state.

Sleep phase

At this time, brain activity is expressed in the production of delta waves, the frequency of which is equal to 2 Hz. This is the most quiet and slow mode.

How sleep phases affect human health and what is the secret of good sleep

For the duration takes about half an hour. In this phase of slow sleep, a person sometimes has dreams.

Deep sleep phase

At this time, a person sleeps deeply and soundly. In the EEG, oscillations of delta waves with a frequency of 2 Hz predominate. The slow and deep phases are often combined under the common name of delta-wave sleep. The duration of the deep sleep phase takes approximately 15% of the total nighttime rest time.

The duration and features of the deep phase have been closely studied by specialists for a long time. It was found that at this time the brain actively produces dreams (about 80% of all visions that a person visits during the night). Dreams are in the form of pleasant images or nightmares. Most of them, when a person wakes up, he forgets.

Despite the fact that the stage of deep sleep does not take much time, it has a strong effect on the body. For example, in young suffering from enuresis, involuntary urination may occur at this time. Persons prone to sleepwalking, at this stage can occur attacks of this disease.

REM sleep

This phase was opened not so long ago (in 1953) and is still being fully studied. It was found that the state of quick rest follows immediately after a deep one and lasts about 10–15 minutes in duration.

REM sleep is a time when brain activity is expressed in the production of waves that are close in frequency to beta waves. The fluctuations of brain activity during this period are very intense and rapid. Hence the name – “fast”. Also this period in the scientific literature is called the phase of BDG, or REM-sleep.

A person who is in this stage is completely immobile. His muscle tone decreases sharply, but his brain activity is close to the waking state. Eyeballs move under covered eyelids.

The connection between vivid, memorable dreams and this phase is the clearest. Being in it, a person sees the most colorful images and plots. If you initiate arousal during the fast phase of sleep, in 90% of cases a person will be able to retell their visions.

On the question of how long this phase of sleep lasts, scientists cannot give a clear answer. Its duration is approximately equal to 20-25% of the total time of night rest. The phase of fast, as well as slow sleep, has a cyclic structure. By the nature of brain activity, the cycles are similar, but the duration varies.

The first cycle occurs approximately 1.5 hours after falling asleep. The time of the next increases a little and so on. In the morning, the duration of the last phase of REM sleep can reach several tens of minutes. In this case, the person sleeps shallowly, until finally he wakes up completely.

Closer to the morning in the body is observed activation of all systems. The hormonal system starts to work more actively. In men, an erection of the penis occurs, in women – the clitoris. Respiratory and heart rate changes. Alternately, each rise and fall in .

Awakening in different phases and rest cycles

The general health and well-being of a person directly depend on the quality and duration of a night’s rest, which has a heterogeneous structure. During the night, the human brain needs to go through the steps described. Only under this condition, the body is fully restored.

Moreover, all phases are equally important. Slow, fast, deep sleep – they all perform important functions. Having learned what a person’s deep sleep is, scientists have established that it is necessary for normal mental activity and preservation of the skills acquired throughout the day. Fast regulates energy resources. Its absence can lead to the death of the organism.

In the phase of deep sleep wake up hardest. Neither the body nor the are ready for awakening. In the brain at this time there are complex neurochemical processes that are best not to interrupt. Knowing what a person’s deep sleep is, it is easy to understand its importance for the preservation of the nervous system.

But during the lung wake up quite simple. At this time, the body is ready for wakefulness, and all brain stabilizing processes are completed. Nevertheless, chronic lack of fast sleep has a very bad effect on health, so doctors advise to get enough sleep.

How much to sleep

The optimal duration of night rest for each person is purely individual. One is enough for a full recovery of 7 hours, others are enough for 10. And yet there are norms for each age group. With their help, it is easy to determine if a person is sleeping enough:

  1. Infants in the womb and newborns rest for 17 hours. And that’s fine. During rest their brain and body grows and develops.
  2. In babies of 3–11 months, sleep gradually decreases to 12–15 hours.
  3. Preschoolers sleep a little less (10-13 hours).
  4. Teenagers need 8-10-hour night rest. Young people 17-18 years old – 7-9 hours.
  5. Approximately the same is supposed to sleep adults (7-9 hours).
  6. Pensioners’ rest is usually reduced by 1-2 hours, and this is also normal.

Sleep time and sleep value

The quality of rest depends on when a person goes to sleep. Doctors advise you to go to bed early, and this is no accident. Putting to bed at 20:00, a person provides himself with a full 7-hour rest and a very deep sleep with high-quality restoration of all body functions.

Anyone who goes to the bedroom after 22:00, “shines” about 4 hours of full sleep. The situation is very bad for citizens who are used to bedding closer to dawn. If you fall asleep at 3:00, then at such a late time the phase of deep sleep will last no more than 15 minutes.

The value of a person’s sleep, who spent the whole night on his feet and “prikornuvshey” only in the morning, is one minute. Naturally, in this mode, neither physical nor intellectual capabilities will be restored. If you live in such a mode for a long time, you will notice problems with memory and concentration, constant fatigue and absent-mindedness.

In general, everyone needs to go through all the phases of the clock from 21: 00-22: 00 before dawn. Only in this case, the person will be healthy and full of energy. Lack of sleep citizens suffer not only from chronic fatigue, but also from the mass of diseases. Among them, neurosis, hypertension, oncology, etc. In addition, chronic lack of sleep significantly reduces life expectancy.

What should be a deep sleep

People for thousands of years living without electricity and the Internet, went to bed with the sunset. Now it seems strange. However, modern citizens do not take into account the fact that over millions of years of evolution, the human brain has adapted itself to orient itself in the movement of the daytime body. For him it is natural.

Changing this mode set by nature, he condemns himself to disease and premature old age. Now, knowing what a person’s deep sleep is and what is the value of a night’s rest at different times, it is easy to understand the importance of each phase.

It is important to adjust your individual mode. Early sleep and a long night of sleep – this is the way to beauty, health and longevity. It helps to burn excess fat and restore wasted energy, improves memory and prompts answers to questions that for some reason stubbornly refuse to be solved during the day.

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