REM and Non-REM Stages of Sleep

During sleep, many things happen in the body. As your sleep starts, your rapid eye movements and non-rapid eye movements cycle begin.

What is Rapid eye movements?

REM refers to rapid eye movement. The brain goes through four different stages. It is one of them in which the eyes move fast in different directions. Rapid eye movement is the final stage, and other three stages are non-REM.

According to research dreams occur while rapid eye movements sleep.

Generally, an individual enters a rapid eye movement sleeps during the initial 90 minutes as they fall asleep. As the sleep cycle continues during the night, several rapid eye movement occurs. Nearly 20-25% adults and 50% infant’s get the rapid eye movements.

Why do eyes move in sleep?

During sleep time if you dream, your eyes move fast from one side to another which happen in REM-rapid eye movement sleep. According to an earlier study, eyes move because we seek around in the dream, but it refused because a blind person also goes under the REM phase and his dream has only emotions and sounds.

Recent studies say that eyes move whenever a change occurs in the scene and the eyes flicker as the image changes in a dream.

According to new research, during REM (rapid eye movement) sleep, the signaling pattern to the brain is similar to the things we imagine or see a new image.

The research of Tel Aviv University discovered that a burst occurs in neurons activity which happened by eyes flickered.  This burst in activity reflects a change in scene or concept which is different from image process while sleeping.

The scientist explained that it is a similar brain activity which happens when a person displays an image which is related to memory.

Dr. Yuval Nir – a co-authored of Nature Communication study said to BBC news explained the neurons burst become quickly active after the 0.30 seconds when an image appears. There is a possibility of a similar occurrence when individual close eyes and imagine an image or concept.

Rapid eye movements sleep Facts

While rapid eye movements sleep, the brain rapid eye movement remains as active like awake. During the rapid eye movements phase, the individual may feel irregular and fast breathing.

It helps to combine the memories. Rapid eye movements sleep gets reduced if an individual drinks alcohol before sleeping. Individuals with rapid eye movements sleep behavior disorder can behave outside of their dreams.

The normal sleep cycle begins with non-rapid eye movement before entering rapid eye movements. The initial rapid eye movements phase normally rapid eye movement remains for 10 minutes. As the rapid eye movements phase repeat, the time of movements progress.

Sleep stages

It is necessary to know the difference between sleeplessness and sleep to understand the characteristics of sleep and sleep stages. Sleeplessness is a phase of consciousness followed by increased perception, environmental responsiveness, realistic thinking, and physical activity.

Whereas, sleep is a behavioral phase of reduced perception, comparatively less responsiveness to the physical inactivity/rest and environment.

A calm body is a most prominent aspect of sleep, but the brain still stays active at different levels. It happens while the brain is balancing the sleep and functioning important tasks. However, the brain stays more active in certain phases than wakefulness.

There is two significant phase of sleep such as rapid eye movement (REM) and non-rapid eye movement (non-REM). The different parts of the brain are responsible for regulating these two sleep phases.

Brainstem regulates the rapid eye movement.

Higher brain center regulates the non-rapid eye movement.

Non- Rapid Eye Movement – Stage 1

Stage 1 of non- rapid eye movement begins when you decide to sleep and close your eyes. It also refers as dreamless sleep, somnolence or drowsy sleep.

During this stage, you will fall asleep for 1 to 10 minutes, and it is possible to awake quickly.

In a scientific way, stage 1 is a phase of transition from nearly unsynchronized gamma and beta brain waves with each frequency of 12 – 30 Hz and 25 – 100 Hz. It is a normal range of awake phase to occur together. The slower alpha waves range from a frequency of 8 -13 Hz and beta waves 4 to 7 Hz. It is challenging to find the exact point of falling asleep. As the process continues, the brain wave activity gets slow.


  • Even if you were sleeping, you feel like you were not sleeping.
  • During this stage, your eyelids slightly appear open, and your eyes begin to roll shortly. Your body muscles also stay active.
  • The heartbeat becomes normal, and your breathing slows down.
  • Your brain temperature and blood pressure slow down.
  • While falling asleep, you may also experience hypnic jerk accompanied by the feeling of falling down. According to some people, it is a human developed vestigial reflex. It occurs while the evolutionary process to stop dropping from the tree they rested on.

Non- Rapid Eye Movement – Stage 2

The non-rapid eyes movement of stage-2 involves light deep sleep. As the stage-1 ends, the individual enters in the 2nd stage of non – rapid eye movement. This phase remains for 10 to 25 minutes. It also identifies as light sleep.

During this phase eye movement stops and overall body, functions slow down.

As sleep cycles continue to occur entire night,  an individual spends more time in non-rapid eyes movement stage 2 than other sleep phases stated by the National Institute of health. Adults are likely to spend 55% of total time in this sleep.

During the 2nd stage, an individual’s body reduces muscle activity, and consciousness starts to fade completely. At this point, the individual may hear the outer sound but unable to understand the content.

The theta brain waves range from stage 1 to stage 2 which characterized by different phenomena such as

Sleep spindles, it is a burst of the brain functions in the area of 12 – 14 Hz which remain for half a second. It also identifies as sigma waves.

K -complexes, it is a high voltage short negative peaks accompanied by the moderate positive complex. The final negative peak occurs with the complex which lasts for 1 – 2 minutes.

These servers combine to protect the sleep and suppress the outside stimuli response. It also helps to combine the sleep based memory and knowledge process because an individual goes through this stage at different times while sleeping at night. It happens in stage 2 more than other stages.


  • The sleep of stage 2 remains for 20 minutes.
  • During this sleep, the body temperature and heart rate get slow.
  • The body signal all muscles to reduce the activity level because the body is going in sleep mode.
  • As it is a deep sleep phase, you will find hard to wake up.
  • The metabolic functions and blood pressure also get slow.

Non- Rapid Eye Movement – Stage 3

This non-REM phase is a combination of stage 3 and stage 4 sleep. The stage three describes as delta, deep, or slow wave sleep. An individual is completely unaware of the outer world during stage 3 sleep.

This stage describes by delta brain waves. It has a frequency of nearly 0.5-4 Hz accompanied with sleep spindles which are lesser than stage 2.

According to the American Academy of sleep medicine, the stage – 3 divided into two stages that stage -3 and stage – 4. It will depend on the delta waves frequency. Earlier stage 4 used to describe when delta waves pass 50% more than it total.


  • During this phase, the non-rapid eye movement begins in 35 to 45 minutes after sleeping.
  • As electroencephalograms display, the brain waves become slower and larger.
  • At this phase, an individual can sleep in extreme noises and disturbances without displaying any reaction.
  • If you awake during non-rapid eye movements stage sleep, then you are more likely to feel confused for some time.

Rapid eye movements – Stage 4

Rapid eye movement is the final phase of the standard sleep cycle. The initial rapid eye movement (REM) sleep phase stays around 10 minutes and commonly occur after staying awake for at least 90 minutes.


  • As this stage name symbolizes that an individual’s eyes move rapidly in a different direction while rapid eye movement sleep.
  • It is a powerful phase of sleep in which dreams occur.
  • Some people experience bedwetting and sleepwalking episodes.
  • You can notice the increased heart rate and raised respiration with irregular rhythms during the 4th stage.
  • Rapid eye movement stages usually get longer in the entire night. Every REM stage can last for an hour.

Rapid eye movement also describes as paradoxical sleep, because the brain waves get a release while this stage which is different to sleep. It’s like you are sleeping, and your brain waves seem as if recording like while you are fully sleepless. Another feature of this paradox is the fact that your brain appears to be more active, but most of your body’s muscles seem paralyzed.

What Is Deep Sleep?

Illustration Tiefschlaf

Deep sleep occurs in stage 3 and stage 4. It also describes as delta sleep or slow wave sleep. An individual in deep sleep cannot wake up with any noise even others find difficult to wake the person. Children also go through deep sleep and unable to wake up which causes them problems such as

  • Bed Wetting
  • Night terrors
  • Sleepwalking

During deep sleep, an individual will not have any muscle activity or eye movement.

Deep sleep provides healthful sleep of all stages and decreases the sleep drive. It is a reason if you take a short sleep during daytime, you can still get the sleep at night. But if you get deep sleep, then you will find difficult to get sleep at the night. It happens because your daytime long deep sleep reduces the needed sleep.

Deep sleep helps human growth hormone to release and makes muscle to get stress free. It also reboots your immune system. Deep sleep also helps the brain to get refresh itself to learn new things.

Sleep Cycle and Age

Sleep can have different cycles which last for a different phase of time during the night. For initial half of the night, the non-rapid eye moments occur, and the second half of night the rapid eye movement occur.

  • It depends on your age the specific amount of time you spend in a particular stage.
  • The infant spends 50% of the time in rapid eye movement stage.
  • Adult spends 20% of the time on REM, and the remaining 30% of the time gets divided into other 3 stages.
  • Whereas old age people progressively spend less time in rapid eye movement sleep.

Learning and memory

According to research, if an individual unable to enter in rapid eye movement sleep, then the individual finds difficulty to remember the what he/she learned before sleeping. It is important that one should get a combination of rapid eye movement (REM) and non-rapid eye movement (Non-REM) sleep to learn and remember.

Development and Central nervous system (CNS)

For proper brain development, an infant needs REM sleep. According to some research, REM sleep is responsible for the development of neural stimulation and mature neural connections.

What happens if you don’t get REM sleep?

Here are things which occur due to the lack of REM sleep.

Decreased managing skill

According to research the animals who denied REM sleep displayed abnormalities in managing mechanisms and preventive responses in unsafe situations.


An individual who lacks enough rapid eye movement (REM) sleep has a link to migraines.


According to the study of Pittsburgh University, the children and adolescent who have short REM sleep related to the overweight problem.

REM sleep behavior disorder

The disorder of REM behavior affects some individuals. It is a condition in which the normal occurrence of muscles paralysis of REM does not happen. It makes an individual act out of a vivid dream.

For example, the individual may yell, kick.

  • Rapid eye movement sleep behavior disorder develops slowly without symptom. It becomes worse over time.
  • REM sleep behavior disorder occurs because of the malfunction of the brain nerve pathways. The progressive risk factors include.
  • Overage of 50
  • Being male
  • Certain medications such as antidepressants
  • Alcohol and drugs withdrawal
  • Developing neurodegenerative disorder

REM and Alcohol

Alcohol influences rapid eye movement sleep. In some cases, drinking alcohol can help to fall asleep quick. According to research, alcohol reduces REM -rapid eye movement sleep. More alcohol contributes to the reduction of your REM sleep.

During the review study of 2013, REM sleep get reduction due to alcohol at moderate levels. Still, low alcohol consumption didn’t show any result.

The REM sleep begins after 90 minutes of falling asleep, and it was notably delaying due to alcohol.

Alcohol also affects sleep in some other ways such as snoring and sleep apnea which may result in frequent restroom visits. It also causes to disrupt the circadian rhythm of the body which is an internal clock setting for managing wake time and sleep.

How to enhance REM sleep

There are many ways to improve the REM and Non-REM sleep to get good sleep benefits. Here are the sleep improvement tips.

Set a bedtime routine

Establishing a specific bedtime routine for every night helps mind and body to sleep.  A consistent bedtime routine helps to increase the sleep quality. It helps to maximize the REM sleep phases during the night.

Overcome night-time waking

You will interrupt the good sleep due to warm temperature, loud noise, and bright lights. You can help your sleep by keeping the cell phones off and reduce the noise. Remove the light which directly irritating your eyes. If you afraid of sleeping in the dark without light, then put some paper around light so it should not point toward eyes and there will be some light in the room. It is important to keep your room temperature around 60 to 67-degrees F.

Get enough sleep

A healthy individual requires 7-9 hours good sleep. Reducing the number of sleep hours causes to decrease the phases of REM sleep.

Medical conditions

Some medical conditions such as sleep apnea cause to influence on the sleep quality and reduce REM sleep.

Recent Scientific study of REM sleep



According to scientific study, REM sleep has a link with two specific genes.

The experiment went on mice. Mice without the genes Chrm1 and Chrm3 sleep shorter hours than normal mice and develop undetectable rapid eye movement sleep levels. This is the first time that REM sleep discovery found essential genes stated by Hiroki Ueda from Biosystem Dynamics Research from RIKEN Center of Japan.

The scientists also found that mice without only Chrm 1 had more shattered and short sleep. The mice without only Chrm3 had insufficient non-Rapid eye movement sleep.

For healthy lifestyle healthy and complete sleep also important. If you experience sleep problems, having short sleep phases check with your doctor and find the underlying cause.



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