Sleep stages 3 and 4 are referred to as

The Stages of Sleep: What Happens During Each

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Medically reviewed by Raj Dasgupta, MD — By Eleesha Lockett, MS — Updated on Sep 30, 2021

It’s no secret that sleep is one of the most important activities for good health. When we sleep, our bodies take time to:

repair muscles
grow bones
manage hormones
sort memories

Sleep can be broadly segmented into rapid eye movement (REM) sleep and non-REM (NREM) sleep. Most adults will enter sleep from the drowsy state into NREM sleep.

NREM sleep is divided into three sub-stages: stage N1, stage N2, and stage N3. Older classification had four stages of NREM sleep. In the current rules, NREM stage 3 and NREM stage 4 are combined as stage N3.

Sleep stages occur in cycles lasting 90 to 120 minutes each. Four to five cycles occur during a typical night of sleep. Shifting of stages occurs over the course of the night, typically with an increased percentage of NREM sleep in the first half of the night and an increased percentage of REM sleep in the second half of the night.

In this article, we’ll explore these stages of sleep, discuss sleep disorders, plus tips for getting better sleep.

Non-REM sleep happens first and includes three stages. The last stage of non-REM sleep is when you sleep deeply. It’s hard to wake up from this stage of sleep.
REM sleep happens about an hour to an hour and a half after falling asleep. REM sleep is when you tend to have vivid dreams.

NREM Stage N1

This stage of non-REM sleep is the typical transition from wakefulness to sleep and generally lasts only a few minutes. Stage N1 is the lightest stage of sleep; patients awakened from it usually don’t perceive that they were actually asleep

During this stage:

Eye movements are typically slow and rolling.
heartbeat and breathing slow down
muscles begin to relax
you produce low amplitude mixed frequencies waves in the theta range (4 to 7 Hz)

NREM Stage N2

This next stage of non-REM sleep comprises the largest percentage of total sleep time and is considered a lighter stage of sleep from which you can be awakened easily. This is the stage before you enter deep sleep.

During this stage:

heartbeat and breathing slow down further
no eye movements
body temperature drops
Sleep spindles and K-complexes are two distinct brain wave features that appear for the first time

NREM

Stage N3

This final stage of non-REM sleep is the deepest sleep stage. Stage N3 sleep is known as slow-wave, or delta, sleep. Your body performs a variety of important health-promoting tasks in this final non-REM stage.

During this stage:

arousal from sleep is difficult
heartbeat and breathing are at their slowest rate
no eye movements
body is fully relaxed
delta brain waves are present
tissue repair and growth, and cell regeneration occurs
immune system strengthens

REM Stage R

There are two phases of REM sleep: phasic and tonic. Phasic REM sleep contains bursts of rapid eye movements, while tonic REM sleep does not.

Stage R occurs about 90 minutes after you fall asleep, and is the primary “dreaming” stage of sleep. Stage R sleep lasts roughly 10 minutes the first time, increasing with each REM cycle. The final cycle of stage R may last roughly between 30 to 60 minutes.

During this stage:

eye movements become rapid during phasic REM
breathing and heart rate increases and become more variable
muscles become paralyzed, but twitches may occur
brain activity is markedly increased

When you fall asleep at night, you cycle through all of these stages of sleep multiple times — roughly every 90 minutes or so.

For something so necessary to our health and well-being, there’s still so much we don’t know about sleep. But here are seven fun facts that we do know:

Human beings spend 1/3 of their lives sleeping, while cats spend roughly 2/3 of theirs asleep. Other animals, like koalas and bats, can sleep up to 22 hours a day.
Newborn babies need roughly 14 to 17 hours of sleep per day, while teenagers require about 8 to 10 hours each night. Most adults need 7 to 9 hours of sleep.
Sleep deprivation can have a hugely negative impact on health. Even as little as 24 hours without sleep can cause significant mood swings, difficulty functioning, and altered perception.
Energy levels naturally dip at two distinct times of the day: 12-2 p.m. and 8-9 p.m. This explains the post-lunch fatigue that some people feel during the middle of the day.
Higher altitudes can have a negative impact on sleep quality. According to research, this may be because of a reduced amount of slow-wave (deep) sleep.
Although there’s still much to learn about sleep, the biggest thing we know is that sleep is just as crucial to good health as nutrition and exercise.

According to the American Academy of Sleep Medicine, the number of people annually who experience a sleep disorder is about 70 million. Sleep disorders can have a negative impact on sleep quality, which in turn can lead to other health problems. Below, you’ll find some of the most common sleep disorders and how they’re treated.

Insomnia

Insomnia is a chronic sleep condition characterized by difficulty sleeping. Some people have trouble falling asleep, others are unable to stay asleep, and some have trouble with both. Insomnia often causes excessive daytime sleepiness and fatigue.

Cognitive behavioral therapy (CBT) is the primary treatment for insomnia. CBT may also be combined with sleep medications, which are able to help people fall and stay asleep. For some people, improving sleep hygiene may also help.

Sleep apnea

Obstructive sleep apnea (OSA) is a condition in which the body stops breathing during sleep. These periods of no breathing, called apnea, happen because the airways of the throat become too narrow to allow air flow. Like insomnia, this condition can negatively affect sleep quality.

The first line of treatment for OSA is a continuous positive airway pressure (CPAP) machine. The CPAP creates enough airflow to allow a person with sleep apnea to breathe properly during sleep.

If the CPAP doesn’t help, bilevel positive airway pressure (BiPAP or BPAP) may be considered to help patients tolerate the pressures. In some cases, an oral appliance or surgery may be necessary for OSA.

Shop all Healthline-approved products for snoring and sleep apnea in our sleep shop.

Restless leg syndrome

Restless leg syndrome (RLS) is a neurological disorder that causes an uncomfortable feeling in the legs, which occurs in the evening as bedtime approaches and when the individual is resting or trying to fall asleep. People with RLS often have trouble getting enough sleep because of their symptoms.

Certain medications are FDA approved to help manage RLS symptoms. Practicing good sleep hygiene can also help relax the body before bed and make it easier to fall asleep.

Shift work disorder

Shift work disorder is a condition that commonly affects those who work outside of a regular 9-to-5 schedule. This disorder can cause an imbalance in the natural circadian rhythm, or sleep-wake cycle. People with this disorder are at a higher risk for increased daytime sleepiness and health issues.

Treatment for shift work disorder includes strategic napping, avoiding stimulants like light at the correct time, and, if possible, reducing the number of hours worked. For people who sleep during the day, it can also help to use light-blocking tools like eye shades or curtains.

Narcolepsy

Narcolepsy is a chronic central nervous system disorder that causes extreme daytime sleepiness with “sleep attacks” along with poor sleep at night. Type I narcolepsy also causes cataplexy, which is a sudden, physical collapse caused by loss of muscle control.

People with both type I and type II narcolepsy often experience extreme disruptions in their daily life.

Medications like stimulants and SSRIs are used to treat the symptoms of narcolepsy. At-home treatments, like good sleep hygiene, diet and exercising regularly, can help to promote healthful sleep.

Dealing with narcolepsy can be challenging. Making adjustments in your daily schedule may help which include strategic napping. Support groups and counseling can help you and your loved ones cope with narcolepsy.

Practicing good sleep hygiene is the best way to get quality sleep at night. Here are some ways you can improve your sleep hygiene:

Spend time outside in the sun during the day. Exposing your body to natural light during the day can help maintain a healthy circadian rhythm.
Exercise or move your body throughout the day. Getting in at least one exercise or movement session each day is a great way to improve your sleep quality.
Limit your nap time to no more than 20-30 minutes. There are benefits to napping. But if you nap for longer than 30 minutes, it can leave you wide awake when it’s finally time for bed.
Avoid stimulants and certain foods before bed. Caffeine, nicotine, or alcohol before bed can interrupt your sleep, as can foods that cause indigestion or stomach upset.
Limit your screen time an hour before sleeping. TVs, phones, and other electronic devices emit blue light, which can interrupt the hormones that help you fall asleep.
Create a comfortable bedroom environment. Investing in a high-quality mattress, pillow, blanket, and other relaxing bedroom items, can help you sleep better. Want suggestions? Browse our market, filled with editor-trusted and expert-verified pillow and mattress recommendations.

Incorporating these tips slowly over time can greatly improve your sleep quality. But if you’re still having trouble falling or staying asleep, it may be time to visit a doctor to discuss more options.

Your body cycles through the stages of sleep each night: three stages of non-REM sleep and one stage of REM sleep. During these sleep cycles, our breathing, heart rate, muscles, and brain waves are all affected differently.

Getting enough sleep is important for health-promoting activities like digestion, growth, and memory. Certain sleep disorders, like insomnia, can cause poor sleep quality and difficulty functioning throughout the day.

The best thing you can do to improve your sleep quality is to address any underlying conditions and work on your sleep hygiene.

Last medically reviewed on September 13, 2021

How we reviewed this article:

Healthline has strict sourcing guidelines and relies on peer-reviewed studies, academic research institutions, and medical associations. We avoid using tertiary references. You can learn more about how we ensure our content is accurate and current by reading our editorial policy.

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Brinkman J, et al. (2021). Physiology of sleep.
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Healthy sleep habits. (2020).
sleepeducation.org/healthy-sleep/healthy-sleep-habits/
Nasca TR, Goldberg R. (n.d.). The importance of sleep and understanding sleep stages.
sleephealth.org/sleep-health/importance-of-sleep-understanding-sleep-stages/
Myoclonus fact sheet. (2016).
ninds.nih.gov/Disorders/Patient-Caregiver-Education/Fact-Sheets/Myoclonus-Fact-Sheet#3160_2
Patel AK, et al. (2021). Physiology, sleep stages.
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Our experts continually monitor the health and wellness space, and we update our articles when new information becomes available.

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Sep 30, 2021

Written By

Eleesha Lockett, MS

Edited By

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Sep 13, 2021

Medically Reviewed By

Raj Dasgupta, M.D.

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Medically reviewed by Raj Dasgupta, MD — By Eleesha Lockett, MS — Updated on Sep 30, 2021

REM & NREM, Sleep Stages, Good Sleep Habits & More

What is sleep?

You may think nothing is happening when you sleep. But parts of your brain are quite active during sleep. And enough sleep (or lack of it) affects your physical and mental health. When you sleep, your body has a chance to rest and restore energy. A good night’s sleep can help you cope with stress, solve problems or recover from illness. Not getting enough sleep can lead to many health concerns, affecting how you think and feel.

During the night, you cycle through two types of sleep: non-rapid eye movement (non-REM) sleep and rapid eye movement (REM) sleep. Your brain and body act differently during these different phases.

What happens in the brain during sleep?

Researchers continue to study sleep and its effect on us. While we’ve learned a lot about sleep, there’s still much that’s unknown.

We know that brain chemicals are very involved in our sleep cycle. Neurotransmitters are chemicals that help the nerves communicate. They control whether we’re awake or asleep, depending on which neurons (nerve cells) they’re acting on:

Neurons in the brainstem (where the brain and spinal cord meet) produce neurotransmitters called serotonin and norepinephrine. These chemicals keep our brain active when we’re awake.
Neurons located at the base of the brain are responsible for us falling asleep. It seems these neurons turn off the signals that keep us awake.

Why do we need sleep?

Sleep helps us in many ways. We need it for:

Growth: In children and young adults, deep sleep (sleep that’s harder to wake from) supports growth. The body releases growth hormone during this type of sleep. The body also increases production of proteins, which we need for cell growth and to repair damage.
Nervous system function: A lack of sleep affects our memory, performance and ability to think clearly. If a person is severely sleep deprived, they may even experience neurological problems such as mood swings and hallucinations. Sleep also helps our nerve cells. They can repair themselves, so they function at their best. And certain nerve connections get a chance to turn on, strengthening our brain and thinking ability.
Survival: Researchers don’t fully understand why sleep is so essential. But studies in animals have shown that getting deprived of REM sleep can shorten lifespans. Lack of sleep may harm the immune system, which protects us from infections.
Well-being: People who don’t get enough sleep are at higher risk for developing various health conditions including obesity, diabetes and heart problems.

What are the stages of sleep?

When you sleep, your brain goes through natural cycles of activity. There are four total stages of sleep, divided into two phases:

Non-REM sleep happens first and includes three stages. The last two stage of non-REM sleep is when you sleep deeply. It’s hard to wake up from this stage of sleep.
REM sleep happens about an hour to an hour and a half after falling asleep. REM sleep is when you tend to have vivid dreams.

As you sleep, your body cycles through non-REM and REM sleep. You usually start the sleep cycle with stage 1 of non-REM sleep. You pass through the other stages of non-REM sleep, followed by a short period of REM sleep. Then the cycle begins again at stage 1.

A full sleep cycle takes about 90 to 110 minutes. Your first REM period is short. As the night goes on, you’ll have longer REM sleep and less deep sleep.

What is non-REM sleep?

Three stages make up non-REM sleep.

Stage 1:

This stage of light sleeping lasts for five to 10 minutes.

Everything starts to slow down, including your eye movement and muscle activity.
Your eyes stay closed. If you get woken from stage 1 sleep, you may feel as if you haven’t slept at all. You may remember pieces of images.
Sometimes, you may feel like you’re starting to fall and then experience a sudden muscle contraction. Healthcare providers call this motion hypnic myoclonic or hypnic jerk. Hypnic jerks are common and not anything to be concerned about as this occurrence is unlikely to cause any complications or side effects.

Stage 2:

This period of light sleep features periods of muscle tone (muscles partially contracting) mixed with periods of muscle relaxation.
Your eye movement stops, heart rate slows and body temperature decreases.
Brain waves become slower. Occasionally, you’ll have a burst of rapid waves called sleep spindles.
Your body prepares to enter deep sleep.

Stages 3

This stage is deep sleep.
During this stage, your brain produces delta waves, very slow brain waves.
It’s hard for someone to wake you up during this stage.
You have no eye movement or muscle activity.
If you’re woken up, you may feel groggy and disoriented for a few minutes.

What happens during non-REM sleep?

During non-REM stages, your body:

Builds bone and muscle.
Repairs and regenerates tissues.
Strengthens the immune system.

As you age, you get less non-REM sleep. Older adults get less deep sleep than younger people.

What is REM sleep?

When you enter REM sleep, brain activity increases again, meaning sleep is not as deep. The activity levels are like when you’re awake. That’s why REM sleep is the stage where you’ll have intense dreams.

At the same time, major muscles that you normally control (such as arms and legs) can’t move. In effect, they become temporarily paralyzed.

Usually, REM sleep arrives about an hour and a half after you go to sleep. The first REM period lasts about 10 minutes. Each REM stage that follows gets longer and longer.

The amount of REM sleep you experience changes as you age. The percentage of REM sleep:

Is highest during infancy and early childhood.
Declines during adolescence and young adulthood.
Declines even more as you get older.

What else happens to the body in REM sleep?

Besides increased brain activity and muscle relaxation, your body goes through a series of changes during REM sleep. These changes include:

Faster breathing.
Increased heart rate and blood pressure.
Penile erections.
Rapid eye movement.

What affects sleep quality?

Chemical signals in the brain influence our sleep and wake cycles. Anything that shifts the balance of these neurotransmitters can make us feel drowsier or more awake. For example:

Alcohol may help people fall into a light sleep. But it reduces the deeper stages of sleep and REM sleep and leads to more disrupted sleep.
Caffeine and pseudoephedrine (drug ingredient) can stimulate the brain. They may cause insomnia, an inability to sleep. Watch out for caffeinated drinks such as coffee and drugs such as diet pills and decongestants.
Medications such as antidepressants can cause less REM sleep.
People who smoke heavily often sleep lightly and have less REM sleep. They may wake up after a few hours because they experience nicotine withdrawal.
Very hot or cold temperatures can disrupt REM sleep. We’re less able to regulate body temperature during REM sleep.

How much sleep do I need?

Many factors affect how much sleep you need. Age is a big factor:

Infants need about 16 hours a day.
Toddlers and preschoolers need about 12 hours.
Teenagers need about nine hours.
Adults need seven to eight (though some are fine with five and others need closer to 10).
Pregnant people often need more sleep during the first trimester.

What is a sleep debt?

If you haven’t slept well or long enough for a few days, you might create a sleep debt. Once your debt builds up, you may feel physically and mentally exhausted. Try to make sure you get enough sleep every night to avoid creating this debt. You can’t necessarily make up your debt by sleeping a lot on the weekends. It’s best to get enough sleep all week long.

Can we adapt to needing less sleep?

Generally, people don’t adapt to getting less sleep than they need. You may feel like you’re used to reduced sleep, but it still affects your function. For example, it can harm your judgment and reaction time.

What is sleep deprivation?

When you’re sleep deprived, you’re not getting the total amount of sleep you need. Signs of sleep deprivation include:

Falling asleep within a few minutes of lying down.
Feeling drowsy during the day.
Nodding off for microsleeps — short periods of sleep during the day when you’re otherwise awake.
Sleep deprivation can be dangerous. Driving while tired causes about 100,000 car accidents each year, according to the National Highway Traffic Safety Administration. It also causes 1,500 deaths. If you feel tired on the road, pull over. It’s not safe to drive if you’re drowsy.

What are sleep disorders?

According to the American Sleep Association, at least 40 million Americans experience sleep disorders each year. Another 20 million have occasional sleep issues. These disorders cause sleep deprivation, leading to problems with work, school, driving and social activities.

There are more than 70 sleep disorders. A few, known as disruptive sleep disorders, lead to moving around or making sounds. Other sleep disorders involve food. And some sleep disorders overlap with psychiatric conditions. If you have problems with sleep or feel very tired, talk to your healthcare provider about a possible sleep disorder.

Some of the most common sleep disorders include:

Insomnia disorder: Many people experience insomnia at some point in their lives, with trouble falling or staying asleep. Sleeping pills can help in the short-term but behavioral strategies to improve sleep including cognitive behavioral therapy for Insomnia (CBT-i) is a much better long term solution.
Narcolepsy: You may suddenly fall asleep during the day, even if you had a good sleep the night before. These “sleep attacks” can last a few seconds or up to 30 minutes. Talk to your provider about your symptoms and additional testing will need to be completed to diagnosis this sleep disorder.
Restless legs syndrome (RLS): You may feel unpleasant sensations in your legs (such as prickling or tingling). You may also have an urge to move your legs to get relief. If you have RLS, talk to your healthcare provider about medication to help improve symptoms.
Sleep apnea: You may experience periods of interrupted breathing while you sleep, a condition called sleep apnea. Often, getting polysomnography (sleep study) in a sleep center is the best way to get properly diagnosed and treated. Sometimes, weight loss or not sleeping on your back can help. But you may need a special device to help you breathe while you sleep.
Snoring: People who regularly snore can have disturbed sleep. They can also disturb the sleep of their bed partner. Snoring often leads to feeling tired during the day. Several treatment options are available for snoring.

What are good sleep habits?

Good sleep habits, also called good sleep hygiene, are practices to help you get enough quality sleep.

Do:

Have a sleep schedule: Go to sleep and wake up around the same time every day, even on weekends and vacations.
Clear your mind before bed: Make a to-do list early in the evening, so you won’t stay awake in bed and worry about the next day.
Create a good sleep environment: Make sure your bed and pillows are comfortable. Turn down the lights and avoid loud sounds. Keep the room at a comfortable temperature.
Exercise every day: Stay active but try to avoid exercising during the few hours right before bed.
Relax: Before bed, take a warm bath, read or do another relaxing activity.
See your healthcare provider: If you’ve been having trouble sleeping or feel extra drowsy during the day, talk to your provider. There are many treatments available for sleep disorders.

Don’t:

Consume caffeine, nicotine and alcohol late in the day: These substances can interfere with your ability to fall and stay asleep.
Lie in bed awake: It’s better to do a soothing activity, like reading, until you feel tired.
Nap during the day: A short nap (less than 30 minutes) is OK if you’re very sleepy. But try to avoid naps after 3 p.m.
Think negative thoughts: Try to avoid a negative mindset when going to bed, such as, “If I don’t get enough sleep now, I won’t get through my day tomorrow!”
Use electronics right before bed: Electronics, such as your phone or tablet, can interfere with your body’s production of melatonin. This hormone gets released before bed to help you feel tired.

A note from Cleveland Clinic

Far from being a state of doing nothing, sleep is an essential part of our lives. It helps our body rest, recharge and repair. There are four sleep stages — three in the non-REM phase plus REM sleep. Many factors can affect sleep quality, including the food and drink you consume before bed and room temperature. Many people experience trouble sleeping now and then. But if you think you may have a sleep disorder, talk to your healthcare provider. Common sleep disorders include insomnia (trouble falling asleep) and sleep apnea (breathing trouble during sleep). Your provider can help you get the diagnosis and treatment you need.

Phases and cycles of human sleep

The body requires daily rest. Normal sleep cycles are necessary for the restoration of the immune system, streamlining the information flow received during the day, and a lot of other functions. Lack of sleep, insomnia affect well-being and vigor. There is a violation of coordination, inhibition of thought processes.

When a person's sleep cycles are constantly disrupted, irreversible and increasing symptoms occur, turning into a chronic form and treatment of the sleep disorder is necessary.

Which phases of sleep (sleep stages) are important for health?

According to statistics, a person needs an eight-hour sleep cycle, consisting of 5 phases of 90-100 minutes each, to replenish health. Each cycle has slow and fast sleep phases:

REM sleep phase. From fatigue or lack of sleep, a person “falls asleep on the go”, uses the slightest opportunity to “take a nap”. He instantly falls asleep and plunges into the phase of a paradoxical dream. The name arose after comparing the electroencephalograms of sleeping people. They revealed similar frequency indicators of heart rate and respiration with those who were awake. But the tone of most muscles was zero, except for the diaphragmatic, auditory ossicles and above the eyelids. The conclusion is that only the body sleeps, and the brain continues to work. The most vivid realistic dreams fall on this phase of sleep. After 20 minutes, sleep enters the second phase - slow.
According to studies, the proportion of slow-wave sleep in humans is 75%. The slow phase is divided into 4 sub-phases:

Slumber. A healthy and observant person will fall into a deep sleep in 5-10 minutes.
Immersion. Duration up to 20 minutes. The heartbeat begins to slow down, the body temperature drops, the brain gives bursts (spindles) of activity to the EEC. Consciousness is completely disabled.
Deep sleep phase.
Delta sleep or deepest sleep. It is also called the REM phase (REM - from the English "Rapid Eye Movement" - "rapid movement of the eyeballs"). At this stage, typical rapid movements of the eyeballs are noted, which determined its name. It is difficult to wake up a person who is in this phase. After a sharp awakening, he will not perceive reality for a long time. It is at this stage that sleepwalking, enuresis, talkativeness in a dream is manifested, nightmares are pestering when people suffer from these disorders.

Next, the sleeper automatically switches to the fast phase and again in a cycle. Passing through all stages gradually, a person wakes up cheerful and rested.

Sleep phases are important for the physiological state

What happens in the body during sleep is of paramount importance. Deep sleep phases are vital for the body to recover physically.

Peace and relaxation of a sleeping person is a visual statement that the body continues to work:

There is a maximum evaporation of moisture through the epidermis, as a result, a slight weight loss.
Collagen, the most important protein for strengthening blood vessels and elasticity of the dermis, is being produced. Compare your face after a good night's sleep and after a sleepless night.
Rost. The concentration of growth hormone is maximum at night's rest. Children must sleep at night.
Immersion in dreams gradually relaxes all the muscle ligaments of the body. The only load remaining is the muscles of the eyelids, so that they do not open in the sleeping person.
Brain rest. Night rest is a brainstorming of the information received during the daytime, sorting and "arranging" for the safety of important and secondary information. At this point, the brain completely stops responding to external stimuli. No wonder the saying is in use - "mornings and evenings are wiser." A person wakes up with a different view of the problem.

The sleep apnea patient usually has disturbed sleep cycles and does not reach the deep sleep phase at night, as he is constantly awakened as a result of alarm signals sent by the body. This significantly worsens the patient's well-being during the day. After a diagnostic night in our laboratory, when the diagnosis of obstructive sleep apnea was confirmed, the patient was indicated for therapy with CPAP devices.

everything about how, how much and why to sleep

Nenad Aksic/Shutterstock. com

Sleep takes up a third of our lives. If you live 90 years, you will sleep through 30 of them. A lot, right? This condition is the subject of research by many scientists around the world (neurologists, psychologists, anthropologists, sociologists). Everyone wonders how much sleep you need? How does sleep affect productivity? What to do if you can't sleep?

Sleep is a special state of consciousness, as well as a natural physiological process, characterized by a reduced reaction to the outside world and specific brain activity.

Israel Sundseth/Unsplash.com

The structure of human sleep includes two phases: slow-wave sleep (Non-REM) and fast sleep (REM, or REM - “rapid eye movement”).

Slow sleep
Comes immediately after falling asleep. Consists of four stages. The total duration of the Non-REM phase is about 90 minutes. The breathing is calm, even, the pressure decreases, the eyes first make slow movements, and then they are motionless, the brain is inactive, the body is relaxed. You rest, restore physical strength.

REM sleep
Follows REM sleep and lasts 10 to 20 minutes. The temperature and pressure rise, the heart beats faster. The body is immobilized, with the exception of the muscles responsible for the heartbeat and breathing. Under closed eyelids, eyeballs make quick movements (hence the name - REM). The brain is active. You see dreams.

Non-REM and REM phases alternate with each other. First, you fall into slow sleep and go through all its stages. It takes about 90 minutes. Then comes the phase of REM sleep. The first time it is short, no more than 5 minutes. This cycle is called the sleep cycle. The cycles are repeated. At the same time, the proportion of non-REM sleep decreases and the duration of REM sleep increases (up to 1 hour). A healthy person usually goes through five cycles of sleep at a time.

Good sleep contributes to success in professional and personal life. Agree, you are unlikely to hear “Yes!” If during the interview you yawn or fall asleep at the screening of your favorite movie of a girl you like.

But most importantly, sleep is a guarantee of health. During sleep, a number of important hormones are produced, tissues are regenerated, and physical strength is replenished. The brain is also not idle: some of its areas become even more active than during wakefulness.

Dyaa Eldin/Unsplash.com

Have you noticed that when you want to sleep, some tasks seem too difficult, but once you get enough sleep, the solution comes by itself? The fact is that during sleep, selective, that is, selective, erasure of memory occurs. The brain analyzes the information received during the day: the unnecessary is sent to the “basket”, and the important from the short-term memory is “archived” into the long-term. This is how our memories are formed. Improves perception, concentration and learning ability.

Lack of sleep impairs the functioning of certain parts of the brain. For example, inhibition of neural processes in the parietal lobe is observed, which may cause problems with the reaction rate. And when the work of the prefrontal cortex slows down, it is difficult for a person to formulate thoughts, there may be problems with vision. Fatigue of the brain turns into a whole bunch of negative consequences.

Deterioration of cognitive functions (memory, attention, thinking), coordination, speech, orientation, control and others. Often this leads to accidents at work and on the road. According to statistics, every fifth accident occurs due to the fact that the driver fell asleep at the wheel.
Immunity vulnerability. Studies show that lack of sleep increases the risk of getting sick by three times. During sleep, the immune system synthesizes cytokines. The more infections around, the more they are required. But if a person sleeps little, then there is simply no time to produce cytokines. No wonder they say that sleep heals.
Overeating and excess weight. Lack of sleep stimulates the production of ghrelin, the hunger hormone. As a result, the person overeats. A tired brain requires more and tastier food.
Reduced productivity. When a person wants to sleep, he does everything slowly and poorly. What usually takes an hour can take two, three or more. And not the fact that it will not have to be redone. The efficiency of time stolen from sleep tends to zero.
Decreased motivation. The constant lack of sleep destroys motivation, as groundwater erodes the foundation. Every day less and less I want to move forward towards my goals.
Bad habits and bad mood. Lack of sleep is a serious obstacle to the formation of good habits. But an excellent catalyst for harmful ones: with a lack of sleep, a person is looking for external stimulants (nicotine, caffeine, and so on). A sleepy person is quick-tempered, irritable and offended by the whole world.
Poor appearance. Lack of sleep is literally imprinted on the face in the form of bruises and bags under the eyes. Prolonged lack of sleep provokes premature aging of the skin.

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The situation is aggravated by the fact that often a person does not realize or does not recognize the decline in their mental and physical abilities: “Sleep is for the weak! I'm fine!".

Long-term sleep deprivation can cause serious health problems: the risk of developing heart and vascular diseases, diabetes mellitus. However, there are people who consider sleep a waste of time and deliberately keep it to a minimum.

Time is the most valuable and, alas, irreplaceable resource.
Wasting it on sleep is a crime.
This is the philosophy of polyphasic sleep supporters.

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Polyphasic sleep is a sleep pattern in which sleep time is broken up into several short periods instead of a long rest once a day. At the same time, the total duration of sleep is significantly reduced, and wakefulness increases to 20–22 hours.

Dymaxion - four times for 30 minutes every 6 hours. Total - 2 hours.
Uberman - six times for 20 minutes every 4 hours. Total - 2 hours.
Everyman - 1.5-3 hours at night and three times 20 minutes during the day. Total - 2.5-4 hours.
Tesla - 2 hours at night and 20 minutes during the day. Total - 2 hours 20 minutes.

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Sleep is shortened by skipping Non-REM phases. According to supporters of the polyphasic pattern, the main energy recharging occurs during REM sleep, which means that you need to immediately “dive” into it, without wasting time on slow sleep.

Of course, training is needed. If you do not know how to fall asleep quickly and do not like to sleep during the day, it will be difficult. But gradually the body will get used to it, and the brain will tune in to the desired wave.

Polyphasic sleep was practiced by many prominent personalities: Leonardo da Vinci, Salvador Dali, Nikola Tesla, Bucky Fuller. Among our contemporaries are the president of Yahoo, Marissa Mayer, businessman and billionaire Donald Trump, basketball player Kobe Bryant and others.

Adepts of polyphasic sleep claim that they feel great: they not only get enough sleep, but are also full of physical and creative energy.

However, there are many critics of polyphasic sleep, who argue that sooner or later this jagged schedule will come back to haunt the problems with the cardiovascular system. Opponents of polyphasic sleep believe that you cannot force the body, you need to listen to your biological clock.

In ancient times, people lived according to the laws of nature - everything depended on the change of time of day. After all, there were only two "lamps": during the day - the sun, at night - the moon. This has shaped human circadian rhythms.

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Circadian rhythm
This is the body's internal clock that determines the intensity of various biological processes (thermoregulation, digestion, hormone production, and so on).

The circadian frequency of sleep and wakefulness depends on light. Visual receptors react to the level of illumination and send a signal to the suprachiasmatic nucleus of the brain. This kicks off the production of two important hormones responsible for sleep and awakening: melatonin and cortisol.

Melatonin is a sleep hormone. Produced in the pineal gland when it gets dark. It reduces pressure and temperature, calms the body and gives it the command “Time to sleep!”. In the morning, the synthesis of melatonin stops. The more light, the more cortisol is released into the blood. This hormone wakes us up, gives vigor and energy for the accomplishments of a new day.

This determines the 24-hour circadian rhythm of sleep and wakefulness: it gets dark - melatonin gives us the opportunity to rest, the sun rises - cortisol wakes us up. But how much sleep do you need to be healthy and positive? After all, for example, in summer the nights are shorter than in winter, and artificial lighting allows you to adjust the natural schedule.

The vast majority of studies have proven that a healthy adult needs 8 hours of sleep.

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This comes from the very nature of sleep. Remember, under normal conditions, we go through five sleep cycles of about 100 minutes each: 100 times 5 divided by 60 is about 8 hours.

The duration of sleep depends on age. The younger the person, the more sleep they need. The National Sleep Foundation, an American non-profit organization with 25 years of experience in the field, makes the following recommendations:

0 to 3 months - 14-17 hours;
from 4 to 11 months - 12-15 hours;
from 1 year to 2 years - 11-14 hours;
from 3 to 5 years - 10-13 hours;
from 6 to 15 years old - 9-11 hours;
from 14 to 17 years old - 8-10 hours;
from 18 to 64 years old - 7-9 hours;
65 years and over - 7-8 hours.

Sleep duration directly affects physical and mental activity. Maybe, to become the best in your field, it is enough to sleep as much as outstanding scientists, writers and politicians slept? There is no definite answer to this question.

Einstein and Schopenhauer slept 10-12 hours a day. Honore de Balzac, Leo Tolstoy and Charles Darwin - 8 hours each. Sigmund Freud and Vladimir Nabokov adhered to six hours of sleep. Mozart and Margaret Thatcher (5 hours each), Napoleon Bonaparte and Voltaire (4 hours each) rested a little less. Waking record holders are Thomas Edison and Nikola Tesla, who practiced polyphasic sleep.

There is no universal recipe. Sleep duration is like shoe size. For most, 8 hours is suitable, but for some this is not enough, and for some it is a lot. To understand how much you need to sleep for you, you can experimentally.

Answer three questions:

Do you need an alarm to wake you up?
Do you drink coffee or energy drinks to keep you awake during the day?
Do you fall asleep within the first five minutes?

Yes to the first two questions and no to the last one, you need to increase your sleep.

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Circadian rhythms also affect a person's psychological state. Depending on the peaks of mental activity, people are divided into two chronotypes: morning (larks) and evening (owls).

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Early rise and early bed. Waking up at 5-8 am. Lights out usually no later than 10 pm. Most productive and efficient until noon. In the afternoon can not solve problems effectively. By evening, completely exhausted.

Get up late and stay up late. Wake up at 9 am or later. Lights out, usually after midnight. Productivity peaks in the afternoon and evening. Waking up early is unsettling.

This classification was invented in the West in the 1970s. Since then, disputes have not ceased, who is better: larks or owls?

Larks are associated with hard work and success. Who gets up early... The world seems to be made for early birds. Government agencies, clinics, shops, organizations - if you want to be in time everywhere, get up earlier. But, according to scientific research and real life examples, owls are no less efficient and successful. For example, for a trader on the stock exchange or an IT freelancer, the generally accepted work schedule is not so important: they have their own.

Sometimes discussions reach the point of ridiculousness: supposedly owls are more sociable and romantic, while larks are more responsible and friendlier. In fact, such subjective qualities do not depend on the chronotype, but on the character of the individual. In addition, there is a sleep regime, the adherents of which are difficult to unambiguously classify as larks or owls.

The theory of biphasic, or segmented, sleep was developed by the historian, teacher at the Virginia Polytechnic Institute Roger Ekirch (Roger Ekirch). The result of his 16-year scientific work, he outlined in the book "When the day ends: a dream in the ages past. "

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Ekirch studied hundreds of historical documents and came to the following conclusion.

Until the 19th century, when artificial lighting spread to homes, people spent up to 14 hours a day in the dark. Winter evenings were especially long and tedious. The so-called two-phase sleep has become a protective mechanism here.

People went to bed almost immediately after sunset. Slept for about 4 hours and then woke up and stayed awake for a couple of hours. What they were doing? Differently. The aristocracy and intelligentsia, who could afford candles, read or prayed. In the 15th century, there were even special prayers for the night vigil. But most often they created, because they felt something akin to insight. Simpler and poorer people, hard workers and peasants, indulged in carnal pleasures. This Ekirch explains the high birth rate in these social groups. After midnight activity, people again went to bed and slept until the first roosters.

Modern experiments have shown that biphasic sleep can actually increase your creativity scores. The fact is that people wake up immediately after REM sleep, when the electrical activity of the brain is similar to the state of wakefulness. The memory is cleared of unnecessary information, the mind is bright, the attention is clear, you are full of creative energy.

Biphasic sleep has been practiced by some tribes since ancient times and is becoming more and more popular in pop culture. Despite the fact that the adherents of this system cannot be attributed either to larks (they go to bed early and get up early), or to owls (they work at night).

This is another argument in favor of the claim that we can change our own chronotype. If desired, an owl can become a lark, and vice versa.

Get up at 6 am! Sounds like a judgment. Can you imagine how difficult it will be to take your head off the pillow and how bad it will be during the day? But this will happen only if the duration of sleep is disturbed. Waking up early doesn't mean sleeping less. Waking up early means sticking to a routine. For example, if the rise is scheduled for 7:00, then you need to go to bed no later than 22:00.

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Why do you want to get up early? Find your motivation. The word "should" doesn't work. Just by forcing yourself, you will inevitably break the regime. Perhaps you dream of losing weight and improving your health? Start jogging in the morning or sign up for a pool. Many of them open early so people can swim before work. Not enough time for self-development? Early morning is perfect for this. Everyone is still sleeping, no one will stop you from writing a note on your blog, reading your favorite book, drawing or, say, lying in the bath for a longer time.

1st minute: open your eyes, think about the people you love, smile.

2nd minute: take a few deep breaths to oxygenate the body, stretch sweetly.

3rd minute: lightly massage the back of the head, temples, eyebrows and earlobes, rub palms together to improve blood circulation.

4th minute: Sit down slowly and drink a glass of water stored in the evening - this will restore the body's water balance and activate the metabolism.

5th minute: get out of bed, open the curtains, fill the room with light, say to yourself: “Good morning!”

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Now take a shower, exercise, meditate and have breakfast. In any order. Physical activity and contrast showers will increase adrenaline levels, a nutritious breakfast will finally awaken your metabolism, and meditation will help you tune in to a new day.

A few more life hacks that will help make the morning really good:

Fill your morning with bright colors and cheerful smells. For example, eat oatmeal off an orange plate and hang citrus pomanders around the house.
Take care of everything from the evening. Iron your clothes, assemble your lunch box, make a plan, and so on. Often you do not want to get up, because you know how many boring things are in the morning.
Do not turn on the radio and TV. News and advertising only spoil the mood. Better get ready for work to your favorite energetic tunes.

Having created the right morning rituals, you will soon feel how getting up with the first rays of the sun sets you in a creative mood, and you will notice that you no longer need an alarm clock.

The first mechanical alarm clock was designed by Levi Hutchins in 1787. He called only once a day - at 4 o'clock in the morning. Modern people hate alarm clocks. These soulless squeakers steal our sleep, so in the hope of extending the sweet moments, we press the "Snooze for 10 minutes" button. In fact, we ourselves make the enemy out of the alarm clock.

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As the morning light fills the room, the body stops producing melatonin and starts producing cortisol. The temperature rises, blood pressure, the level of PER protein in the blood. Your body is preparing to wake up. Therefore, observing the regimen, you open your eyes just a few moments before the alarm signal.

The Snooze button breaks this process. You begin to doze off again, falling into the first stage of non-REM sleep. The body is perplexed: melatonin is needed again, but what to do with cortisol ?! As a result, after 5–10 minutes you force yourself to get up, but you feel lethargic and overwhelmed.

“Nonsense! I never wake up before the alarm, you won’t wake me up with a gun!” If so, then you simply do not sleep enough and do not follow the regime.

To make friends with the alarm clock:

do not use the Snooze button;

set a pleasant melody, the volume of which slowly increases;

keep the alarm clock away to turn it off after the first 5 minutes of waking up, when you have already got out of bed.

Insomnia (insomnia) is a sleep disorder characterized by inadequate sleep duration and/or poor quality of sleep. It occurs in people of all ages. Insomnia can be chronic (lasts from a month or more) and acute (several nights in a row).

Symptoms:

You can't sleep at all.
Constantly waking up.
You are pissed that you are not sleeping well.
Everything falls out of hand, I don't want to communicate with anyone.

Possible causes:

Stress, problems at work and in private life, depression.
Non-compliance with the regime. Deciding to lie around longer on the weekend, you can earn insomnia.
Shift work schedule, and as a result - disruption of circadian rhythms.
Medicines. Investigate if insomnia is a side effect of the drug you are taking.
Violation of sleep hygiene (stale air in the room, too hot, noisy or light).

In addition, insomnia can be a companion of somatic and neurological diseases. Here you need to see a doctor. But in most cases, you can get rid of insomnia on your own.

Most often, our own thoughts prevent us from falling asleep. Not always pleasant.

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There are various techniques to stop the round dance in the head. For example, visualization. Imagine yourself dozing on the beach under the lapping of the waves. The more detailed the picture, the faster you will find yourself in the realm of Morpheus. Another technique is auto-training: “My eyelids are getting heavy, I fall asleep…”. You can also run the events of the outgoing day in reverse order or dream up and tell yourself a bedtime story.

Also try focusing on your own breathing: inhale deeply through your nose for 4 seconds, hold your breath for 7 seconds, and exhale slowly through your mouth for 8 seconds. Thanks to this exercise, you will calm down, and while counting seconds, you will have no time to think about anything else.

Thank you for the passing day. Who or what are you grateful for today? From a positive psychology point of view, expressing gratitude strengthens interpersonal relationships and is highly motivating. Falling asleep with good thoughts, you set yourself up to continue the chain of goodness tomorrow.

Sometimes we can't fall asleep because of some trifle like an uncomfortable posture or a chemical smell from bed linen. But in the science of sleep, there are no trifles. Pay attention to the position of the body in which you usually wake up. Lie down like this the next time you can't sleep. Use special candles or an essential oil lamp to fill your bedroom with the soothing scent of lavender.

But the most important thing is to work out and follow the evening rituals that set the body to sleep.

Keep a diary. There you can record the events of the passing day, your thoughts and experiences. Give preference to a pen and paper notebook.
Read. Better - a regular book or an e-book with an E-Ink screen. And no horror, action and drama. Choose light, positive pieces.
Planning. By making a plan in the evening, you will not only save time in the morning, but will also be ready for action.
Communication. Evening is a time for family and friends. Do not engage in intellectual work at night looking. And communication is not social networks and chats, but a live conversation.

In addition, proper nutrition, meditation and walking will help normalize sleep.

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Many people think you have to be tired to sleep well. Physical activity really has a positive effect on the quality and duration of sleep. But intense training is recommended to end at least 4-6 hours before bedtime.

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Light aerobic exercise, yoga or just meditation can be done 1-2 hours before bed.

One of the best yoga postures for relaxation is shavasana. Lie on your back. Place your hands along the body with palms up, but do not touch the body. Stretch your legs and spread them a little. Close your eyes. Relax one by one all the muscles of the body, starting with the toes. Gradually move up: buttocks, lower back, abdomen, back, chest, and so on. Finish relaxing with the muscles of the neck, face and eyes. Usually by this point the person is disconnected.

But the best option for evening physical activity is a walk. You will enrich the body with oxygen, literally step over the worries and anxieties of the day and, perhaps, work up an appetite.

Eating at night is harmful. But going to bed when your stomach is growling with hunger is wrong. The last meal should be 2-3 hours before bedtime. At the same time, you need to eat foods that are conducive to relaxation.

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Specifically, rich foods:

melatonin, sleep hormone;

tryptophan, an amino acid from which melatonin can be synthesized;

calcium, which promotes the absorption of tryptophan;

magnesium - a natural muscle relaxant that helps to relax;

a protein that lowers the acidity of the stomach and causes drowsiness.

Cherry juice or fresh cherries. This berry contains a lot of melatonin, and contains the hormone itself, and not its predecessor. Regular consumption of cherry juice significantly increases the duration of sleep.
Bananas. They are rich in magnesium and also contain tryptophan.
Yogurt or low-fat cottage cheese. Dairy products are high in calcium and protein.
Turkey, legumes, eggs. These are low-calorie, nutritious foods that help lower stomach pH and induce sleepiness through tryptophan.
Spinach and other dark greens, pumpkin seeds, almonds. Rich in magnesium to help relax muscles and help you fall asleep.

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Avoid fatty foods, coffee and caffeinated foods, and alcohol before bed. The first can cause indigestion and adversely affect the figure. Coffee, black tea, energy drinks and other caffeinated products will keep you awake for a long time. They should be discarded at least 3 hours before bedtime. The last cup of espresso must be drunk no later than 14:00. At night, it is better to drink herbal teas with chamomile, oregano, lemon balm or hawthorn. They will help you calm down and relax.

Alcohol is especially insidious. It helps to switch off, but it has a bad effect on the REM phase, and due to dehydration and the breakdown of ethanol, we wake up without having time to rest. So a jar of beer or a glass of wine before bed is not the best sleeping pill.

It is better to drink a mug of warm milk with honey. Milk contains tryptophan, protein and calcium. This drink has a warming and lulling effect. Just like in childhood.

Sometimes the cause of insomnia lies not in us, but in our partner, who lies next to us and snores. Do not rush to hit him with a pillow - help him solve this problem. Snoring is the process of breathing during sleep, in which a person makes a characteristic rattling sound. According to statistics, 45% of adults snore in their sleep at varying intervals.

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Snoring can be a sign of certain diseases (apnea, obesity, hypertension, and others), but the most common cause of snoring is weakened throat muscles, clogged nasal passages, or palatal vibration.

Throat muscles lose tone with age. But they can be strengthened with some simple exercises.

Close your mouth and close your lips as tightly as possible for 30 seconds.

Open your mouth, move your lower jaw to the right and hold for 30 seconds. Then repeat the same on the other side.

Stick out your tongue as far as possible, then relax. Repeat 10 times. Stick your tongue out again and try to touch your chin and then your nose. Repeat 10 times.

Alcohol, coffee and sedatives relax the throat muscles. And smoking blocks the airways, causing irritation of the mucous membranes of the throat and nose. Therefore, sometimes, to get rid of snoring, it is enough to give up bad habits.

And the simplest thing: change your posture. During sleep on the back, the muscles of the lower palate relax, the tongue sinks, and pressure on the airways appears. Therefore, sleep on your side or stomach, raise the pillow higher or use a special orthopedic pillow.

Churchill never missed an afternoon nap, even during the war. The politician believed that an afternoon nap, like nothing else, increases efficiency. And he was right. Daytime naps are really helpful. Especially if you don't get enough sleep at night.

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Winston Churchill wrote: “You must sleep between lunch and dinner, and no half measures, never! Take off your clothes and get into bed. Don't think that you will do less work because you are sleeping during the day. This is a stupid opinion of people who have no imagination. On the contrary, you will be able to do more, because you get two days in one - well, at least one and a half.

Short nap improves memory and other cognitive functions. It helps to transfer accumulated information from short-term to long-term memory.

Such sleep stimulates creativity and enhances the ability to learn.

It helps to resist stress and improves mood.

10-20 minutes. This is the ideal length of daytime sleep. You will pass the first two stages of slow wave sleep and wake up easily, having time to rest your mind and body.

30 minutes. After half an hour of daytime sleep, a state of inertia similar to a hangover may occur. It will continue for another 30 minutes.

60 minutes. After such a smoke break, it is easy to remember facts, faces and numbers. But for a while you will act by inertia.

90 minutes. A complete sleep cycle has been completed. It is easy to wake up, you feel a surge of strength.

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When, how and where to take a nap

The best time for a siesta is from 13:00 to 16:00. But specific hours depend on your routine and biorhythm. For example, if you wake up at 10:00, you are unlikely to want to take a nap in just 3 hours.

Daytime sleep takes some getting used to. Practice it for several days at the same time. Try to sleep the same number of minutes. Consider the time it takes to fall asleep. If you switch off in 10 minutes, then for a full 20-minute daytime sleep, you need to start the alarm clock half an hour ahead.

You can take a nap anywhere: in the car, at the table, on the couch. The sleep is short, which means that you almost do not risk getting up with back or neck pain. Ideally, find a quiet place with dim lights. If the office does not have this, use a sleep mask and earplugs.

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Stick to the routine. Go to sleep and wake up at the same time according to your internal biological clock. Use special tracker applications to study the features of your sleep.

Create a comfortable sleep environment. The optimal temperature in the bedroom is 18-21 ºС. Ventilate the room at night. Shade windows so that the light of outdoor advertising, street lamps and passing cars does not interfere with you. If you sleep more than one, discuss with your partner what factors affect your and his sleep, and create comfortable conditions for both.

Buy a comfortable mattress, pillow and sleepwear. Change bedding as often as possible. Do not let pets in bed.

Walk and meditate before bed.

Don't lie down on an empty stomach, but don't overeat either. No coffee or alcohol at night.

Use the bedroom only for sleep and sex. Do not watch TV in bed, do not use a laptop, tablet and smartphone. The light from the screens suppresses the production of melatonin - the quality of sleep decreases.

Avoid digital noise at least 2-3 hours before bed. Instead of scrolling through social media feeds, watching emails and watching videos, go about your evening rituals.
Learn more

Dangers of catfish

Different types of projection

How to tell if your boyfriend is using you

Chest hurts from stress

Bulimia eating disorder

Self preservation psychology in relationships

Topics to start conversations

How to describe feeling

What do teens need

How to remove mannerism

Getting past resentment in a relationship

Sleep stages 3 and 4 are referred to as

The Stages of Sleep: What Happens During Each

NREM Stage N1

NREM Stage N2

NREM

Sleep apnea

Restless leg syndrome

Shift work disorder

Narcolepsy

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