At what stage of sleep do you dream

Brain Basics: Understanding Sleep | National Institute of Neurological Disorders and Stroke


Sleep is an important part of your daily routine—you spend about one-third of your time doing it. Quality sleep – and getting enough of it at the right times -- is as essential to survival as food and water. Without sleep you can’t form or maintain the pathways in your brain that let you learn and create new memories, and it’s harder to concentrate and respond quickly.

Sleep is important to a number of brain functions, including how nerve cells (neurons) communicate with each other. In fact, your brain and body stay remarkably active while you sleep. Recent findings suggest that sleep plays a housekeeping role that removes toxins in your brain that build up while you are awake.

Everyone needs sleep, but its biological purpose remains a mystery. Sleep affects almost every type of tissue and system in the body – from the brain, heart, and lungs to metabolism, immune function, mood, and disease resistance. Research shows that a chronic lack of sleep, or getting poor quality sleep, increases the risk of disorders including high blood pressure, cardiovascular disease, diabetes, depression, and obesity.

Sleep is a complex and dynamic process that affects how you function in ways scientists are now beginning to understand. This booklet describes how your need for sleep is regulated and what happens in the brain during sleep.

Anatomy of Sleep

Several structures within the brain are involved with sleep.


The hypothalamus, a peanut-sized structure deep inside the brain, contains groups of nerve cells that act as control centers affecting sleep and arousal.  Within the hypothalamus is the suprachiasmatic nucleus (SCN) – clusters of thousands of cells that receive information about light exposure directly from the eyes and control your behavioral rhythm.  Some people with damage to the SCN sleep erratically throughout the day because they are not able to match their circadian rhythms with the light-dark cycle.  Most blind people maintain some ability to sense light and are able to modify their sleep/wake cycle.

The brain stem, at the base of the brain, communicates with the hypothalamus to control the transitions between wake and sleep.  (The brain stem includes structures called the pons, medulla, and midbrain.)  Sleep-promoting cells within the hypothalamus and the brain stem produce a brain chemical called GABA, which acts to reduce the activity of arousal centers in the hypothalamus and the brain stem.  The brain stem (especially the pons and medulla) also plays a special role in REM sleep; it sends signals to relax muscles essential for body posture and limb movements, so that we don’t act out our dreams.

The thalamus acts as a relay for information from the senses to the cerebral cortex (the covering of the brain that interprets and processes information from short- to long-term memory).  During most stages of sleep, the thalamus becomes quiet, letting you tune out the external world.   But during REM sleep, the thalamus is active, sending the cortex images, sounds, and other sensations that fill our dreams. 

The pineal gland, located within the brain’s two hemispheres, receives signals from the SCN and increases production of the hormone melatonin, which helps put you to sleep once the lights go down.  People who have lost their sight and cannot coordinate their natural wake-sleep cycle using natural light can stabilize their sleep patterns by taking small amounts of melatonin at the same time each day.  Scientists believe that peaks and valleys of melatonin over time are important for matching the body’s circadian rhythm to the external cycle of light and darkness.

The basal forebrain, near the front and bottom of the brain, also promotes sleep and wakefulness, while part of the midbrain acts as an arousal system.  Release of adenosine (a chemical by-product of cellular energy consumption) from cells in the basal forebrain and probably other regions supports your sleep drive.   Caffeine counteracts sleepiness by blocking the actions of adenosine.

The amygdala, an almond-shaped structure involved in processing emotions, becomes increasingly active during REM sleep. 

Sleep Stages and Mechanisms

Sleep Stages

There are two basic types of sleep:  rapid eye movement (REM) sleep and non-REM sleep (which has three different stages).  Each is linked to specific brain waves and neuronal activity.  You cycle through all stages of non-REM and REM sleep several times during a typical night, with increasingly longer, deeper REM periods occurring toward morning. 


Stage 1 non-REM sleep is the changeover from wakefulness to sleep.  During this short period (lasting several minutes) of relatively light sleep, your heartbeat, breathing, and eye movements slow, and your muscles relax with occasional twitches.  Your brain waves begin to slow from their daytime wakefulness patterns.


Stage 2 non-REM sleep is a period of light sleep before you enter deeper sleep.   Your heartbeat and breathing slow, and muscles relax even further.  Your body temperature drops and eye movements stop.  Brain wave activity slows but is marked by brief bursts of electrical activity.  You spend more of your repeated sleep cycles in stage 2 sleep than in other sleep stages.


Stage 3 non-REM sleep is the period of deep sleep that you need to feel refreshed in the morning.  It occurs in longer periods during the first half of the night.  Your heartbeat and breathing slow to their lowest levels during sleep.  Your muscles are relaxed and it may be difficult to awaken you.  Brain waves become even slower.


REM sleep first occurs about 90 minutes after falling asleep.  Your eyes move rapidly from side to side behind closed eyelids.  Mixed frequency brain wave activity becomes closer to that seen in wakefulness.  Your breathing becomes faster and irregular, and your heart rate and blood pressure increase to near waking levels.   Most of your dreaming occurs during REM sleep, although some can also occur in non-REM sleep.  Your arm and leg muscles become temporarily paralyzed, which prevents you from acting out your dreams.  As you age, you sleep less of your time in REM sleep.  Memory consolidation most likely requires both non-REM and REM sleep.

Sleep Mechanisms

Two internal biological mechanisms–circadian rhythm and homeostasis–work together to regulate when you are awake and sleep.  

Circadian rhythms direct a wide variety of functions from daily fluctuations in wakefulness to body temperature, metabolism, and the release of hormones.  They control your timing of sleep and cause you to be sleepy at night and your tendency to wake in the morning without an alarm.  Your body’s biological clock, which is based on a roughly 24-hour day, controls most circadian rhythms.  Circadian rhythms synchronize with environmental cues (light, temperature) about the actual time of day, but they continue even in the absence of cues.  


Your body's biological clock is based on a 24-hour day and controls most circadian rhythms. These rhythms affect a variety of functions including body temperature (represented as the white line on the chart above). Melatonin - a hormone released by the pineal gland - helps you feel sleepy once the lights go down. The peaks and valleys of melatonin (represented as the gold line above) are important for matching the body's circadian rhythm to the external cycle of light and darkness.

Sleep-wake homeostasis keeps track of your need for sleep.  The homeostatic sleep drive reminds the body to sleep after a certain time and regulates sleep intensity.  This sleep drive gets stronger every hour you are awake and causes you to sleep longer and more deeply after a period of sleep deprivation.

Factors that influence your sleep-wake needs include medical conditions, medications, stress, sleep environment, and what you eat and drink.  Perhaps the greatest influence is the exposure to light.   Specialized cells in the retinas of your eyes process light and tell the brain whether it is day or night and can advance or delay our sleep-wake cycle.  Exposure to light can make it difficult to fall asleep and return to sleep when awakened.

Night shift workers often have trouble falling asleep when they go to bed, and also have trouble staying awake at work because their natural circadian rhythm and sleep-wake cycle is disrupted.  In the case of jet lag, circadian rhythms become out of sync with the time of day when people fly to a different time zone, creating a mismatch between their internal clock and the actual clock. 

How Much Sleep Do You Need?


Sleep needs change with age as shown on the chart above. Initially, babies sleep 16-18 hours a day. School-age children and teens need about 9.5 hours of sleep each night. Most adults require 7-9 hours of sleep at night. However, older adults (age 60 and above) tend to sleep for shorter periods at night.

Your need for sleep and your sleep patterns change as you age, but this varies significantly across individuals of the same age.   There is no magic “number of sleep hours” that works for everybody of the same age.  Babies initially sleep as much as 16 to 18 hours per day, which may boost growth and development (especially of the brain).  School-age children and teens on average need about 9.5 hours of sleep per night.  Most adults need 7-9 hours of sleep a night, but after age 60, nighttime sleep tends to be shorter, lighter, and interrupted by multiple awakenings.  Older people are also more likely to take medications that interfere with sleep. 

In general, people are getting less sleep than they need due to longer work hours and the availability of round-the-clock entertainment and other activities. 

Many people feel they can "catch up" on missed sleep during the weekend but, depending on how sleep-deprived they are, sleeping longer on the weekends may not be adequate.

Dreaming and Sleep Tracking


Everyone dreams.  You spend about 2 hours each night dreaming but may not remember most of your dreams.   Its exact purpose isn’t known, but dreaming may help you process your emotions.  Events from the day often invade your thoughts during sleep, and people suffering from stress or anxiety are more likely to have frightening dreams.  Dreams can be experienced in all stages of sleep but usually are most vivid in REM sleep.  Some people dream in color, while others only recall dreams in black and white.


Tracking Sleep Through Smart Technology

Millions of people are using smartphone apps, bedside monitors, and wearable items (including bracelets, smart watches, and headbands) to informally collect and analyze data about their sleep.  Smart technology can record sounds and movement during sleep, journal hours slept, and monitor heart beat and respiration.  Using a companion app, data from some devices can be synced to a smartphone or tablet, or uploaded to a PC.  Other apps and devices make white noise, produce light that stimulates melatonin production, and use gentle vibrations to help us sleep and wake.

The Role of Genes and Neurotransmitters

Chemical signals to sleep     

Clusters of sleep-promoting neurons in many parts of the brain become more active as we get ready for bed.  Nerve-signaling chemicals called neurotransmitters can “switch off” or dampen the activity of cells that signal arousal or relaxation.  GABA is associated with sleep, muscle relaxation, and sedation.  Norepinephrine and orexin (also called hypocretin) keep some parts of the brain active while we are awake.  Other neurotransmitters that shape sleep and wakefulness include acetylcholine, histamine, adrenaline, cortisol, and serotonin.

Genes and sleep

Genes may play a significant role in how much sleep we need.  Scientists have identified several genes involved with sleep and sleep disorders, including genes that control the excitability of neurons, and "clock" genes such as Per, tim, and Cry that influence our circadian rhythms and the timing of sleep.   Genome-wide association studies have identified sites on various chromosomes that increase our susceptibility to sleep disorders.  Also, different genes have been identified with such sleep disorders as familial advanced sleep-phase disorder, narcolepsy, and restless legs syndrome.  Some of the genes expressed in the cerebral cortex and other brain areas change their level of expression between sleep and wake.  Several genetic models–including the worm, fruit fly, and zebrafish–are helping scientists to identify molecular mechanisms and genetic variants involved in normal sleep and sleep disorders.  Additional research will provide better understand of inherited sleep patterns and risks of circadian and sleep disorders. 


Sleep studies

Your health care provider may recommend a polysomnogram or other test to diagnose a sleep disorder.  A polysomnogram typically involves spending the night at a sleep lab or sleep center.  It records your breathing, oxygen levels, eye and limb movements, heart rate, and brain waves throughout the night.   Your sleep is also video and audio recorded.  The data can help a sleep specialist determine if you are reaching and proceeding properly through the various sleep stages.  Results may be used to develop a treatment plan or determine if further tests are needed.

Tips for Getting a Good Night's Sleep


Getting enough sleep is good for your health.  Here are a few tips to improve your sleep:

  • Set a schedule – go to bed and wake up at the same time each day.
  • Exercise 20 to 30 minutes a day but no later than a few hours before going to bed.
  • Avoid caffeine and nicotine late in the day and alcoholic drinks before bed.
  • Relax before bed – try a warm bath, reading, or another relaxing routine.
  • Create a room for sleep – avoid bright lights and loud sounds, keep the room at a comfortable temperature, and don’t watch TV or have a computer in your bedroom.
  • Don’t lie in bed awake.  If you can’t get to sleep, do something else, like reading or listening to music, until you feel tired.  
  • See a doctor if you have a problem sleeping or if you feel unusually tired during the day.  Most sleep disorders can be treated effectively.

Hope Through Research

Scientists continue to learn about the function and regulation of sleep.  A key focus of research is to understand the risks involved with being chronically sleep deprived and the relationship between sleep and disease.  People who are chronically sleep deprived are more likely to be overweight, have strokes and cardiovascular disease, infections, and certain types of cancer than those who get enough sleep.  Sleep disturbances are common among people with age-related neurological disorders such as Alzheimer’s disease and Parkinson’s disease.  Many mysteries remain about the association between sleep and these health problems.  Does the lack of sleep lead to certain disorders, or do certain diseases cause a lack of sleep?  These, and many other questions about sleep, represent the frontier of sleep research.

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.


  • 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.


  • 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.

Sleep and health

SLEEP is a condition that, through certain neurophysiological, chemical, psychological changes, enables us to be physically, mentally and emotionally efficient the next day. Human sleep can be divided into several stages:

FIRST STAGE (it can also be called relaxed wakefulness) - superficial sleep. During this period, we are still awake, but the frequency of breathing, heart rate decreases, and the level of blood pressure and muscle tone also gradually decrease.

STAGE TWO sleep is a deeper (medium-deep) sleep during which blood pressure, heart rate, respiration rate continue to drop, and muscles further relax. At this moment, we stop responding to minor external stimuli, to the usual noise outside the window or in the apartment. In this phase, twitching of the arms and legs may occur, sometimes involving the whole body, the so-called sleepy tremors.

THE THIRD STAGE (now decided to be combined with the fourth), is called deep sleep, or delta. During deep sleep, important processes occur: the accumulation of the necessary substances for the full functioning of the body, the synthesis of amino acids, regeneration processes, somatotropic hormone (growth hormone) is synthesized. The function of the stage with rapid eye movements is psychological adaptation, ordering, analysis of the information received during the day, the formation of a program for future behavior, and the formulation of a response to the challenges received. It is important to understand that poor sleep, and even more sleep pathology, causes changes, leads to the appearance of concomitant diseases. If emotional stress, anxiety, depression cause sleep disturbances, then the sleep disorder itself causes emotional disturbances, memory loss, concentration, reaction speed, decreased libido, and impotence. It turned out that our sleep is very different. We can say that we sleep in certain fragments, each of which is called a cycle. There are two phases in the cycle: non-REM sleep and REM sleep. Then, when the REM phase ends, the next fragment begins, then another. There are 4-6 such cycles in total. It is very important that these phases - non-REM and REM sleep - are presented differently during sleep: the first of them occupies 75%, the second - 25%. Slow sleep is called slow sleep, because slow activity is determined on the electroencephalogram, vegetative activity subsides, the pulse slows down, blood pressure decreases. This is probably a very important period, allowing the body to accumulate certain forces and energy. At this time, the anabolic process takes place. REM sleep is so unusual that it is even called paradoxical. The brain registers rapid rhythmic activity, rapid eye movements occur, and muscles that relax in non-REM sleep relax even more. Vegetative and endocrine "storms" arise, blood pressure, respiration, heart rate fluctuate, and finally, it is at this time that we see dreams. This means that 25% of our sleep falls on sleep with dreams. Thus, out of 60 years of life, a person spends 20 years in sleep, of which 5 years - in REM sleep, i.e. in dreams (there are no people who do not see dreams, but only those who remember them or do not remember them). This organization of sleep helps answer the question of why it is needed.

“Sleep is needed because we really need the accumulation of energy and strength that we spend during the period of wakefulness, active activity. Only after sleep do we feel fully rested. In the evening it seems that you no longer have a reserve of strength, you feel "exhausted", and in the morning you are again ready for vigorous activity. We spend a quarter of sleep on dreams, our brain is actively working during this period. The number of neurons working during sleep is very large and no less than during wakefulness; you just need to understand what the essence of this work is. If for the whole organism it is the accumulation of energy and vigorous activity, then when we talk about work in a dream, we mean active mental activity. Psychic phenomena that occur in a dream can be described as psychological defense. When a person falls asleep, information is sorted, some important information goes into long-term memory, unimportant information is eliminated.

There are people who sleep for a long time, there are those who sleep little, they differ from each other in temperament, attitude to life, and psycho-physiological appearance. There are "larks" and "owls" adapted to either later or earlier work, as well as "pigeons" who are less pressured by these rhythms and can more easily adapt to both nocturnal and daytime activities. The state in which a person spent the night largely determines his ability to realize his life program. Therefore, sleep ensures not only the very continuation of life, but also, which is very important, its quality. Full sleep enables a more complete realization of a person in a waking state, thus, the problem of sleep has not only medical, but also social aspects, the importance of which can hardly be overestimated.

It has been proven that long periods of “lack of sleep” have a negative impact on the quality of life: a sense of humor disappears, irritability, isolation, obsession with the same problems appear. Losing just 4 hours of sleep reduces response by 45%. Memory worsens, exacerbation of various diseases is possible.


1. Try not to accumulate periods of "lack of sleep".

2. Avoid alcohol and caffeinated foods before bed.

3. It is known that the quality of sleep is also harmed if you go to bed hungry or, conversely, having eaten a lot. The most burning question is sleeping on an empty stomach. For many, it just doesn't work. In fact, nutritionists recommend that at least 2-3 hours pass from the moment of the last meal to sleep. Thus, the body will not be busy digesting food, and you will fall asleep much faster. And instead of working on digesting food, your body will be set to rest.

HOWEVER, SLEEPING A LOT IS NO LESS HARMFUL THAN LACK OF SLEEP. The ideal sleep duration for an adult is 7-8 hours per day. Some experts believe that women need an extra hour of sleep because they are more emotional.

Children need to sleep at least 10 hours a day for the normal functioning of the body. Adequate sleep can reduce their manifestations of attention deficit hyperactivity disorder and improve behavior. 20 minutes of extra sleep improves a child's school performance.

Since we spend a third of our lives sleeping, it is important to make the best use of this time to restore the body. The bed should be comfortable, the sleeping room should be dark and well ventilated, and the body position itself should be correct. In addition to the fact that sleeping in a distorted position can cause chronic neck and lower back pain, it can also cause headaches, sleep apnea, heartburn, and stomach pain. Not to mention snoring.


Even though sleeping on your stomach aids digestion and can stop snoring, the habit of sleeping in this position provokes pain in the neck and spine. The main reason is that the head has to be turned because it is impossible to breathe through the pillow.

Bending one of your legs at the knee and putting your arm under your head only makes the situation worse, as the muscles of the neck and shoulder complex become tense and the spine curves. Back pain with the habit of sleeping on your stomach is only a matter of time.

Why is it comfortable to sleep on your stomach?

Doctors believe that a person tends to sleep in the position in which it is most convenient for him to breathe - the less air passes through the throat during sleep, the more likely the person is to sleep on his stomach. This also explains why this position reduces snoring.

In contrast to sleeping on your stomach, sleeping on your back reduces the flow of air into your lungs, causing a louder inhalation and exhalation sound. Among other things, this position is not recommended for those who are prone to temporary pauses in breathing during sleep (apnea).


In this position, the spine is in a neutral position, which helps the body to effectively recuperate. However, remember that the pillow during such a dream should be as thin as possible (high increases the load on the neck), and the mattress should not be too soft, but not too hard. Additional pillows under the knees and lower back will make sleeping in this position more comfortable.


When sleeping on your side and on your back, you need a correct, not too high, pillow and a mattress that conforms to the shape of the body, able to absorb the load.

Suitable for everyone, side sleeping is also considered one of the best positions. At the same time, which side you sleep on plays an important role - sleeping on the right side can provoke heartburn, and sleeping on the left reduces the production of acid in the stomach and is useful for reflux disease.

The most correct position for sleeping on your side is to stretch them along the body - putting your hands under the pillow, you can cause both neck pain and an unpleasant feeling of numbness.


Remember that the habit of sleeping in the wrong position can be extremely persistent - it is likely that at first you will find it extremely uncomfortable to sleep in the correct position. This is especially important for those who are used to sleeping on their stomachs. When choosing a comfortable sleeping position, first make sure that the mattress and pillow are chosen correctly, then proceed to testing sleep on your back - if such a dream does not seem comfortable even with two supportive pillows, go to sleep on your side.

  • Bedroom - sleep only

Be sure to allocate a separate room for the bedroom. Believe me, it will be much easier and more comfortable to live this way, especially if you do not live alone. You will not have to wake up every time from the sounds of pouring water and other extraneous noises.

The next "enemies" of sound sleep are all digital technology. Psychologists, somnologists and interior designers repeat with one voice - down with all computers, laptops, tablets and even TV! Especially TV! All these extraneous "inhabitants" of the bedroom negatively affect the quality of your sleep, and sometimes can even cause insomnia. Remember this variety of LEDs and various sound signals from gadgets - the realm of constant stimuli.

Tip of the day! Move even the phone - the eternal distraction - to another room. Instead, leave only the classic alarm clock in the room.

  • Mattress is the head of everything

Thoughtful interior of the room and the right wallpaper will not help you fall asleep if you have a bad mattress. That is why the choice of such an important thing for you must be approached as carefully as possible.

  • Darkness is your true friend

It is necessary to sleep in the dark. And no exceptions. It's all about the hormone melatonin, which is very necessary for sound and healthy sleep. It is produced exclusively in the dark and helps to sleep better and sleep well. Of course, in large cities it is very difficult to achieve darkness that is comfortable for sleep - advertising billboards, car headlights, bright lights obviously do not contribute to sleep. That's why it's so important to take good care of the windows in your bedroom.

As an option, you can hang very thick dark curtains, they will be an excellent protection against unwanted street lighting and give you a long-awaited twilight.

Do not forget that you may be disturbed by the light not from the street, but from the neighboring room. That is why it is highly undesirable to install a door with glass in the bedroom. Any turning on of the light will immediately create discomfort for the sleeper.

The second nuance, which is also worth dwelling on, is the type of lighting. Experts do not recommend using the main lighting in the bedroom, as it becomes an additional source of heat, which is not a plus, especially in the summer heat. It is better to have a neat night light with a calm light that will help you fall asleep more quickly.

  • Quiet and cool

Yes, this is exactly the kind of atmosphere that a bedroom should have – quiet and cool. And you need to take care of this in advance - even at the stage of buying or repairing an apartment. Do not repeat once again how extraneous sounds interfere with sleep. Therefore, complete soundproofing of the bedroom, thought out in advance, is highly desirable. Be sure to consider the location of your future bedroom: in any case, do not place it on the south side, otherwise it will always be very hot in it, which does not contribute to a good rest at all. Ideal conditions for good sleep are temperatures in the range of 18-21 ° C.

Of course, this is not always possible, so it is advisable to provide for the presence of an air conditioner. You can also use well-known folk remedies - damp sheets and water containers placed on the floor (preferably near the fan).



We usually think of sleep as one single experience when we go to bed every night. But our mind and body experience different phases of sleep during the night, each with its own characteristics and benefits.


Sleep stages are formed by two different types of sleep: non-REM sleep (NREM sleep) and REM sleep (REM sleep). However, before we reach these periods of sleep, there is a stage where we are simply awake. To fall asleep, we begin this stage at rest.

NREM sleep stages is when our body slows down. All activity related to our brain waves, heartbeat, breathing and muscles is reduced to a lower level than when we are awake as our body uses this time to repair and improve our various systems. It is also a type of sleep that is rarely associated with the dream state (although vivid dreams can still occur, but are less likely).

Stages of non-REM sleep include:

  • First stage: the easiest stage of sleep. Our entry point is where we begin the transition into deeper sleep but are still easily woken up by the noises around us.
  • Second stage : Deeper stage of sleep when heart rate and body temperature decrease, but loud noises can still wake us up. This stage is characterized by rapid bursts of high-frequency brain waves thought to be important for learning and memory.
  • Third stage : Often referred to as deep sleep or non-REM sleep. It is very difficult for us to wake up in stage 3. In this stage, the body repairs tissues, builds bones and muscles, and strengthens the immune system.

REM sleep is REM sleep when our body experiences bursts of rapid eye movements and brain activity, similar to how our body behaves when we are awake. This is a type of sleep associated with vivid dreams and a kind of sleep paralysis where our muscles lose the ability to move (so it's not the stage where people sleepwalk, for example). REM sleep is vital to our memory and emotional regulation as our brain processes and clears what we no longer need.


All of the above stages of sleep together form a whole sleep cycle, which usually lasts from 90 to 110 minutes. So, if you sleep eight hours a night, your body will complete several sleep cycles that will repeat until you wake up.

During the night, each sleep cycle is different: the deepest sleep occurs in the first half of the night, and the REM sleep occurs in the second half. So by the time you get to the early hours of the morning, you'll basically be alternating between NREM sleep and REM sleep.


During each sleep cycle, the body experiences each stage of sleep for varying durations, depending on how long you rested. Here is how long each sleep stage lasts in adults:

  • NREM Stage 1 : 1 to 7 minutes in our initial sleep cycle, which is 5-10% of total sleep duration.
  • NREM Stage 2 : 10 to 25 minutes in the initial sleep cycle and lengthens with each successive cycle, eventually accounting for 45 to 55% of our total night of sleep.
  • NREM Stage 3 : 20 to 40 minutes in our initial sleep cycle and accounts for about 15-25% of our total night's sleep.
  • REM sleep : only 1 to 5 minutes in the initial sleep cycle, but lengthens with each successive cycle.


As already mentioned, REM sleep begins in short periods and then gradually becomes longer. We usually have our longest REM sleep in the morning, just before waking up. That's why you often remember your dreams more clearly if you've had a long, uninterrupted night of sleep.

Since we have several intervals during the night, each of a different duration, it is not easy to determine exactly how much REM sleep we need. However, if we don't get enough sleep throughout the night, we are more likely to miss sleep cycles with longer sleep stages. Thus, an adult needs at least seven to nine hours of sleep each night.


When we talk about light and deep sleep, we mean the stages of non-REM sleep. Light sleep occurs in stages 1 and 2, and deep sleep occurs in stage 3.

As we saw above, all stages of sleep are important because they work together in a cycle to allow our body to fully rest and regenerate throughout the night. Therefore, it is very important to get a good night's sleep in order to have a good rest and benefit from the different stages.

Often, when our sleep is disturbed, we lose deep sleep. This means we miss out on the time our bodies need each night to reap the benefits of phase 3 sleep, such as improving your memory and learning functions, supporting cell growth, and boosting your immune system.

If you are interested in getting enough deep sleep every night, you should rethink your sleep patterns to create the ideal conditions for a full night's rest. Some studies have also shown that exercising 90 minutes before bed can increase the duration of deep sleep (but may decrease the duration of REM sleep).

While deep sleep is vital, light sleep also has its benefits. For example, when we wake up naturally during this part of our sleep cycle, we are more likely to feel rested and ready to start the day—a very different morning feeling than when an alarm goes off while you are in deep sleep.


If you slept until noon as a teenager and wake up at dawn as an adult, you have probably noticed how your sleep changes throughout your life. This is how our need for sleep and experience of sleep change as we age.