Sleep phases, sleep cycles, how much sleep you need, and whether you can get enough sleep

Sleep phases: table

Physiologists have been trying to discover the secrets of sleep for several centuries in a row. In the 20th century, somnologists recorded bioelectrical fluctuations that appear in the brain at the moment of immersion in dreams. Experts have found that a person, while resting, goes through several specific cycles, occurring sequentially.

The doctor installs sensors on the subject’s head and records signals coming from the sensors. First, the device receives slow oscillations from the sleeping patient, then more rapid ones, then the phases of the dream change from accelerated to slow .

Stages of slow-wave sleep

Oscillations in a slow rhythm are divided into 4 successive stages. The table shows the characteristics of each period.

Stages of slow-wave sleep

Stages of REM sleep

The slow phase gradually develops into a fast one. At this stage, the heartbeat accelerates, body temperature rises, and breathing becomes rapid. During REM sleep, a person's eyeballs move intensely under drooping eyelids. Internal organs are actively involved in work, muscle tissue is as relaxed as possible.

Nerve cells are regenerated and central nervous system functions are restored . The brain functions intensively. Vivid emotional dreams appear in the subconscious.

When waking up, people retell the pictures they saw in detail. The brain easily produces processed information that came from the real world during the day. Consciousness and subconsciousness interact closely: they exchange data, compare facts, and issue fresh decisions. The brain produces brilliant ideas.

People waking up at this stage do not experience any discomfort. They get up in a good mood, feel a surge of strength, and feel great.

Increasing the duration of the fast (paradoxical) stage improves memory, raises intelligence, and stimulates mental activity. Colorful dreams last longer.

Sequence of stages

If a person is healthy, the phases change sequentially:

• first there is a immersion in sleep (stage 1);
• then stages 2, 3 and 4 follow each other;
• The countdown begins: stage 4, 3 and 2;
• the cycle ends with REM sleep.

The alternating phases create a single cycle that occurs up to 4-5 times during the night’s rest. The length of dreams at each stage is different in time. In cycle I, deep sleep is short-lived, and at the final stage it sometimes does not occur at all.

The length and sequence of periods is influenced by the psycho-emotional state of a person.

Sleep duration according to age

The duration of the deep phase is different for all people. Some people need 4 hours to feel completely rested, while others need 7-10 hours to recover.

In adults, delta sleep takes up to 70-80% of the entire night's rest. With increasing age, this figure decreases. Insomnia accelerates human aging. Adjusting the daily routine helps to increase the duration of rest:

• 2 hours before bedtime, increase physical activity on the body;
• in the evening give up coffee, tonic drinks, alcohol and smoking;
• do not eat food at night (at dinner they eat a small, light dish);
• ventilate the bedroom before resting;
• turn off the lights, curtain the windows;
• eliminate noise sources.

Common sleep-related mistakes

In order for a night's rest to bring complete restoration of strength and a positive charge of energy, it is necessary not to make mistakes that lead to sleep disturbances and insomnia. Recommended:

• do not violate the routine, you should go to bed and get up at the same time, do not shorten or increase the optimal duration of sleep;
• do not eat food before bedtime, the recommended time is 2–2.5 hours before bedtime;
• do not stay in a stuffy room before going to bed; ventilation or an evening walk are recommended;
• do not give up the pleasure of taking a warm bath before bed, it will help you relax, calm down and fall asleep quickly;
• do not go to bed after midnight and do not get up before five o'clock in the morning;
• do not sleep in an uncomfortable position.

In addition to strictly observing the listed prohibitions, you can make it a rule to do morning exercises in any form (running, swimming).

Calculating sleep phases will help develop a regime that will be optimal for each individual person. Following it will help you wake up cheerful, full of strength and energy, and maintain a positive attitude throughout the day.

Features of awakening in each phase

In terms of timing, sleep is of little use in the early morning, from 4 to 6 o'clock. Waking up at dawn is ideal.

People who rise with the sunrise are full of strength and have a clear mind. A person who constantly gets up at dawn does not feel tired and is not bothered by illness. He manages to do much more work than when waking up late.

All phases of dreams are important to people. You can get a good night's sleep if you have 4-5 full cycles during the night, lasting 1.5-2 hours . Every person is unique. There is no general ideal time to wake up. Owls get up in high spirits at 8-10 am. Larks feel great if they get up early, at 5-6 o'clock.

The phases of sleep have a certain significance for awakening. A good time for recovery is considered to be the border period, when one cycle passes into another. This stage is short, it lasts only 2-3 minutes.

Required duration of rest by age

There is no specific norm. Individual characteristics of people influence sleep time:

• age;
• wrong lifestyle;
• lack of daily routine;
• sleep disorder

A newborn baby recovers in 12-18 hours, school-age children - 7-8. On average, people are able to get enough sleep in 7-10 hours. If one stage of sleep replaces another in the correct mode, then all cells in the body are renewed in a short time.

In adults, the stages are reproduced in the same sequence if they are healthy.

Sleep disturbance occurs in sick and elderly people. Their fast period duration is only 18%, and the slow stage does not occur at all.

In old age, many people experience insomnia. Due to chronic lack of sleep, proper night rest is impossible.

The quality of dreams suffers greatly if a person has developed pathologies of the brain and spinal cord. The symptoms that accompany these diseases do not allow you to rest properly. The patient is constantly in a state of superficial dreaming.

In exceptional cases, people can remain without sleep for quite a long time . But you need to clearly understand that chronic lack of sleep has a negative impact on human health. Your sleep schedule needs to be adjusted properly.

The optimal period for falling asleep is considered to be before midnight.

Why is REM sleep important?

During REM sleep, the brain “sorts” new information and selectively stores it into long-term memory. Moreover, most often the information that is recorded in the brain is that it has an emotional overtone or is necessary for survival.

Thanks to REM sleep, a kind of brain reboot occurs, which adapts the nervous system to external changes. For example, the REM sleep phase helps you deal more easily with recent stress and quickly get used to new external conditions.

At the beginning of the article it was said that if you wake up a person in the REM phase, he will retell his dream in detail. However, you should not disturb the sleeping person unnecessarily. Firstly, it has a bad effect on the human psyche. Secondly, with frequent sudden awakenings, sleep becomes interrupted, while attentiveness suffers and performance decreases.

Normally, the REM sleep phase in an adult should occupy at least 20% of the total sleep time. In older people, the duration of this phase should be more than 15% of the duration of sleep.

To increase REM sleep, it is suggested that you should go to bed before 10 pm. However, in practice, the time of falling asleep does not affect the duration of the REM phases.

American scientists claim that dementia (senile dementia) is caused by a shortening of the REM sleep phases. According to them, shortening each phase by just 10 minutes increases the risk of disease by more than 10%.

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Another pathology that is associated with a decrease in the duration of REM sleep is narcolepsy . With this disease, a person literally falls asleep on the go, in any place and in any position.

How to calculate sleep stages so you know when it's best to wake up

An online calculator can help you determine what time is best to go to bed and get up. The action of the instrument is based on identifying human biological rhythms. But this method is far from perfect. The calculation mechanism uses averaged parameters. It is not possible to enter individual indicators.

Only somnologists working in special centers are able to perform a conscious calculation of cycles. The doctor places sensors on the head that allow one to calculate personal physiological processes. The device reads signals received by sensors from the brain. The data obtained is included in a calculation formula designed to establish the frequency and duration of sleep phases.

It is difficult to correctly determine the cyclical nature of dreams using independent calculations. To find out the duration of the stages, use a special formula.

The slow stage lasts on average 2 hours, and the fast stage - 20 minutes. From the time of immersion in a dream, 3-4 stages of 140 minutes are counted. Set your alarm clock for the best time to wake up.

If a person goes to bed at 24:00, then he should be woken up from 06:40 to 07:00.

Adequate sleep is the key to excellent physical and mental health. Lack of sleep and insomnia provoke the development of various disorders in the body and cause many serious diseases. The correct daily routine and getting up at the best hours allow you to rest well and recuperate.

Source

Why is the sequence of phases disrupted?

In healthy people, the sequence of phases and stages of sleep is specific and does not change. You can always set the exact time of going to bed and getting up. Changes are observed in young children and the elderly. The daily sleep duration of infants is 15–20 hours per day, and in older people this figure is reduced to 4–5 hours per day.

For these age categories, it is recommended to maintain a calm environment in the house so that awakening occurs naturally and does not cause nervous tension.

It is more difficult when an adult suffers from insomnia and is in a state of depression. In these cases, REM sleep becomes longer, leading to frequent awakenings. In this case, the period of deep sleep is significantly reduced or completely disappears. Such disorders do not allow the body to fully recover. The consequence of lack of sleep is emotional excitability and energy exhaustion, which negatively affects the mental and physical state.

Scientists distinguish three groups of sleep disorders:

1. Presomnic.
2. Intrasomnic.
3. Post-somnia.

In each individual case, this is determined by a specialist during an examination. Most often, disorders are caused by a tendency to stop breathing during sleep and a sudden transition to the awakening phase.

More information about sleep stages in the video:

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Human sleep - the whole truth about dreams, interesting facts

20% of dreams contain places and people that a person has encountered in real life. Most pictures are unique to one specific dream. Scientists know this because some people have the ability to see their dreams as observers without waking up. This state of consciousness is called lucid dreaming, which is a big mystery in itself. Dreams are symbolic. The things and persons that appear to us are symbols of our own attitude towards them, symbols of our internal difficulties and contradictions. But if you persistently dream about something, you will definitely be given a sign in a dream. Almost 2/3 of people have experienced déjà vu based on dreams. External factors can influence our dreams. For example, if the room is cold, you may dream that you have decided to vacation in Antarctica. About 90% of people have colored dreams. Among those under 25 years of age, this percentage is even higher – 95%. The explanation is that the younger generation did not see black and white televisions. Men see about 70% of men in their dreams, while for women the proportion of “men to women” is approximately equal. Animals also dream. From an evolutionary perspective, REM sleep, where dreams occur, is the last stage of development that can be found in humans, as well as other warm-blooded mammals and birds. For those born blind, dreams are limited to the senses of smell, sound, touch, emotion and taste. The REM sleep stage appears in a person already in the third trimester of pregnancy. A developing fetus can “see” something in terms of brain activity long before its eyes open because the developing brain operates based on innate and biological patterns of time and space. Complete sleep cycles in the usual sense of the word come to a person much later. More often than not, dreams show negative rather than positive emotions. The most popular emotional state in sleep is anxiety. People rarely remember dreams or don’t remember at all; they tend not to notice/ignore what may cause them anxiety, although this does not solve the problem (if there is one). Dreams do not prophesy diseases, but register the first subtle signs of their manifestation. If a dream is one-time, this does not mean that it is a diagnostic dream. But you should pay attention to a dream that is repeated many times, unpleasant, disturbing, clearly remembered. This is a warning dream. Most likely, dreams in green and blue tones indicate that everything is fine with you, red warns of a fever or an infectious disease, yellow-brown tones indicate intestinal diseases, black indicates a nervous breakdown. People snore only during the slow phase of sleep, and they do not dream during snoring. People who quit smoking have much more vivid dreams than smokers or those who have never smoked.

Sleep phases

Scientists are only beginning to approach deciphering the secrets of dreams and the very state of sleep, the secrets of which, it seemed, were discovered by the ancients, and they skillfully used them.

Sometimes it seems to us that we dream all night, or don’t dream at all. Neither one nor the other is true. Usually a dream lasts from several seconds to several minutes, and if it seems to us that we are not dreaming at all, we simply do not remember them. In fact, the brain is never completely at rest during sleep, just as it is in the waking state. But at night, the part of our brain that is “silent” during the day becomes active. Its constituent neurons enter into an active “dialogue”.

For quite some time now, scientists have established that brain activity during sleep has a certain sequence, the phases of sleep replace one another. While awake, the brain is in the beta phase. If a person becomes thoughtful, the brain frequencies slow down and approach the speed of the brain in a state of sleep. The more excited a person is, the higher the frequency of his brain vibrations. In this state it is very difficult to concentrate, it is often difficult to make a certain choice or sit still. This condition does not at all contribute to falling asleep, so for people prone to overexcitation, doctors advise them to take a walk before bed to calm down, or prescribe sedatives.

After a person falls asleep, the REM sleep phase begins - the alpha state. In this state of brain activity, a person dreams. Typically this sleep phase lasts 8-30 minutes. In this state, the eyeballs rotate quickly, breathing is rapid, and the brain uses the same amount of energy as during wakefulness. At this time, you have very vivid, memorable dreams. The REM sleep state is also called paradoxical sleep, and lucid dreaming mostly occurs during this time. After 20-30 minutes, the sleeper enters the delta sleep phase. This is a state of deep, dreamless sleep. In Hinduism, it is generally accepted that at this time the human soul unites with a single, universal consciousness. The delta sleep phase is closed for research. During slow-wave sleep, a person's breathing is deep and slow. Metabolism also slows down. After 30 minutes, the REM sleep phase begins again. If you wake up after 10 minutes of paradoxical sleep, you may remember your dream before the onset of the next phase of delta sleep.

A person awakens after each phase of paradoxical sleep, but memories of this are not retained. During the night, this cycle can be repeated 4-5 times.

It should also be said about the transitional state between sleep and wakefulness - at this time one can observe spontaneous visions and dream images that arise in the human brain before he falls asleep.

Often, after waking up, it seems to us that we had a dream all night, but meanwhile it lasted only a few seconds. The frequency of brain oscillations in a state of meditation corresponds to the frequency of brain oscillations of a sleeping person. In this state it is possible to work with the subconscious.

If you wake up in the morning in a calm environment, smoothly emerging from REM sleep, you usually remember what you dreamed. If at the moment of awakening you come out of a long sleep phase, then you usually do not remember the dream.

In conclusion, some interesting information. Alpha waves are ideal for meditation; if your brain manages to vibrate in the alpha range (8-13Hz), you feel peace, general well-being, and decreased anxiety. Alpha state is the state of creative geniuses. Theta waves precede the state of deep sleep (delta), this state is largely mysterious, characterized by high memory activity, access to the subconscious, the possibility of sudden insights, and creativity. This condition is difficult to reach, because... a person cannot stay in it for a long time; he falls into a deep sleep.

Is it good to oversleep?

Lack of sleep has a very negative effect on the body and well-being in general, but oversleeping cannot bring anything good. The fact is that when you increase the number of hours of sleep contrary to your needs, your biorhythms become disrupted. The body mistakenly begins to think that the more a person sleeps, the better he will feel. But in fact, having overslept the norm, a person feels even more broken. His heart rate rises and his blood pressure jumps. In general, all systems of the body fail, since the body does not understand the timing of the dream.

Experts once conducted an interesting study in which 2 groups of people of 500 people each took part. One group slept no more than 6 hours a day, including naps, and the other group slept more than 9 hours. The first group of volunteers were found to have health problems. About 12% were at risk of premature death due to heart failure and other health problems.

The second group of experimenters was amazed by the fact that the risk of premature death was recorded in 30% of people. A definite conclusion was made that you need to sleep in moderation and when the body requires it. It is compliance with this condition that guarantees excellent health, good spirits and longevity.

Every person should fall asleep in favorable and comfortable conditions. It is by following this rule that your sleep will be complete and will bring only positive results. Sleep time also directly depends on the quality of your dreams and your well-being. For each individual person, the period for getting enough sleep will not be the same. It depends on the age and personal characteristics of the individual.

When do you have dreams?

We spend about a third of our lives sleeping. That is, if a person lived for 75 years, then he slept for 25 of them. Yes, this is a lot, but it is simply impossible to imagine an adequate existence of humanity without full and sufficient sleep. Tests on animals that were deprived of sleep showed that complete sleep deprivation inevitably leads to death after 2-3 weeks for no apparent reason at autopsy.

Sleep is no less important in the process of life than digestion, excretion and metabolism. Sleep is necessary not only for physical rest and recuperation, but is also important in a person’s adaptation to cyclical natural phenomena (changes in time of day, seasons). The role of sleep in the process of memorizing, storing and processing information received during the day is undeniable. Also, during a night's rest, metabolism is normalized and the body's immune reactions are activated.

Sleep phases

When do you have dreams? Sleep is a cyclical process, consisting of alternating slow and fast phases. These phases were identified using electroencephalograph devices, then EEG. The principle of EEG operation is based on the fact that the electrodes of the device “read” waves of electrical activity of the brain from the surface of the scalp.

In turn, the slow-wave sleep phase is divided into 4 stages of falling asleep (the first two are shallow sleep, the second two are deep sleep):

1. The first stage is drowsiness, lasting 5-10 minutes, which is accompanied by muscle twitching, half-asleep dreams, illusory thoughts and ideas. At this stage, muscle activity, pulse and respiration rates, blood pressure, body temperature decrease, metabolism and brain function slow down.

2. The second stage is light or shallow sleep, lasting up to 20 minutes. Brain activity, pulse and respiration rates, blood pressure and temperature continue to decrease progressively.

3. The third stage is transitional, deep sleep. This stage is practically no different from the fourth stage - the stage of even deeper sleep, and they are often combined together. At this time, the brain completely stops its work, rests and recovers as much as possible; it is almost impossible to wake up a sleeper at this stage. But a person can talk or walk in his sleep, but then does not remember anything. When dreams occur in the slow phase, they are blurry, not emotionally colored, rather like thoughts without vivid pictures and plots, and therefore are almost not remembered.

EEG waves in the second phase have the shape of a spindle - bursts of activity alternate with slow waves of low amplitude; in phases 3 and 4 the waves become high-amplitude, but also remain slow.

4. REM phase of sleep, the fifth stage - paradoxical sleep, is accompanied by rapid movements of the eyeballs. This is the main difference between the fast phase and the slow phase. In addition, the electrical activity of the brain, which is determined using EEG, during these minutes is close to the activity of the waking brain. In this case, the person is practically motionless - the tone of large muscles is reduced to the maximum, only the extraocular muscles and the diaphragm continue to work, breathing and heart contractions become more frequent, and blood pressure rises. Waking up a person, despite high brain activity and readiness to work, also seems to be a very difficult task, hence the second name for sleep - paradoxical.

Phase structure of sleep and its features

Somnology is the science of sleep, which has long determined its structure. The average healthy rest consists of five phase cycles. Each takes approximately one and a half hours. During this time, dynamic changes between the slow and fast phases occur. Each stage has its own specifics and functions.

Cyclical nature of sleep

Biphasic night rest in humans follows circadian rhythms. These are the body’s basic settings, triggered depending on the time of day and lighting level.

It is important to know! Day length is the main “guideline” for sleep cycles. Starting in the early morning, changes in the concentration of photodependent proteins in the biosystem occur.

Phases of sleep: their signs, composition and meaning

The physiological state of rest is composed of two phases: slow and fast. A typical cycle lasts about two hours. Three quarters of the time is spent in the orthodox mode. Only 1/4 of the part is allocated for the paradoxical period.

Fast

The fast-wave stage is “responsible” for processing daytime information. During this period, events are filtered and interaction with the human subconscious occurs. This feature is provided for by nature for a reason - it helps adapt to the changing conditions of reality.

Interrupting the REM sleep phase is harmful, as it leads to the development of mental pathologies. As the cycles change, the duration of the paradoxical phase increases. The onset is accompanied by external signs:

• low muscle tone;
• active movements of the eyeballs under closed eyelids;
• slight arrhythmia of breathing and pulse.

During the paradoxical phase, the most vivid, memorable dreams occur.

Slow

Researchers claim that it is during the slow period that physical strength is restored, rehabilitation and regulation of the body’s main biological systems occur. The Orthodox period is conventionally divided into four stages of human sleep. Each of them has special characteristics, different depths and awakening thresholds.

Let's look at them in more detail:

• Stage I – drowsiness. The onset is marked by minimal levels of alpha rhythms responsible for wakefulness. The line between oblivion and reality blurs, and the first images of dreams appear.
• II – I stage – superficial. Blackout is interspersed with high auditory sensitivity (the person is easily awakened).
• The third interval of the slow phase is characterized by an increased depth of dreams.
• IV - delta sleep: low sensory activity, awakening is difficult.

The duration of the slow stage is approximately one and a half hours, then the transition to the paradoxical phase occurs.

Alternation of stages

Let's consider the usual process of two-phase human rest:

• As soon as your head touches the pillow, the lights are turned off, and the sounds of the night city have switched to a gentle mode, a sweet slumber begins. This is the first short stage of slow-wave sleep.
• If the transitions to the 2nd and 3rd stages were successful (nothing and no one disturbed the peace), the brain plunges into the deep delta phase.
• After this, the orthodox flow changes direction in the opposite direction: gradually moving from the 4th “turn” to the previous stages.
• If everything went correctly, without violations, the fast period begins.
• After the active stage, light sleep occurs again, then continues in the same order until the delta phase (slow sleep).

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Changes in stages can be compared to a musical “mix”, where the orthodox stage is the main theme, and the fast stage is the periodic ri.