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What is REM sleep? - Are you getting enough?

Updated: 19/08/2022
8 Min
Simon Igild
Simon Igild

What is REM sleep? - Are you getting enough?

Updated: 19/08/2022
8 Min
Simon Igild
Simon Igild

Table of Contents


Many people mistakenly believe that the primary function of REM sleep is to dream, which is incorrect.

However, REM sleep involves various essential functions ranging from brain development to emotional processing. 

We'll explore the mysteries of REM sleep, why we need REM sleep, what happens when we don't get enough REM sleep, and what sleep disorders are associated with this sleep stage.


What Happens During Non-REM Sleep?

The first stage of sleep is also known as non-REM sleep. It consists of four stages, which are N1, N2, and N3.

Stage 1

Although your eyes are closed, you are easily awakened.

This stage could last between 5 and 10 minutes.

Stage 2

You're falling asleep.

Both your heart rate and body temperature will slow.

Your body is getting ready for deep sleep.

This can last anywhere between 10 and 25 minutes.

Stage 3

This is the deep sleep stage.

It is more difficult to rouse you at this point, and if you are, you will be disoriented for a few minutes.

During the deep stages of NREM sleep, the body repairs and regrows tissues, builds bone and muscle and strengthens the immune system. 

What is REM sleep?

REM sleep is one of the most critical stages of sleep​1​. It is characterized by rapid eye movement and dreaming. The REM cycle alternates with non-REM sleep every 90 to 120 minutes.

REM sleep occurs at the end of the sleep cycle.

It is the final stage of sleep before beginning a new sleep cycle. 

REM has the following important characteristics:​2​

  • Linked to dreaming, irregular muscle movements, and rapid eye movements.
  • Sensory stimuli are more difficult to arouse a person than during Slow - wave sleep.
  • During an episode of REM sleep, people tend to awaken spontaneously in the morning.
  • Motor tone loss, increased brain O2 use, increased and variable pulse and blood pressure
  • ACh levels have risen.
  • The brain is extremely active during REM sleep, increasing brain metabolism by up to 20%. 

What happens to the body during REM sleep? 

It is believed that REM aids in memory consolidation by strengthening the connections between nerve cells in your brain, which may explain why you remember your dreams more vividly than other types of dreams. 

REM sleep is also thought to have therapeutic effects on mental health because it is when your brain releases hormones that keep you happy and healthy. 

This type of sleep is essential for the brain's ability to store and recall memories. It also helps people wake up feeling more alert and refreshed. 

During REM sleep, brain waves are high-frequency, low-amplitude beta waves. This means your eyes are moving quickly, but your muscles are relaxed or paralyzed, so you can't act out what you see in your dreams.

Why REM sleep is essential

The human brain is a complex organ that needs to be adequately regulated. But how important is REM sleep? Sleep is the best way to regulate your brain, and it's important to take naps when necessary.

Getting more REM sleep has many benefits. It can help reduce stress, improve mood and even make you more productive.

The first benefit of getting more REM sleep is that it reduces stress. When you don't get enough sleep, your body will produce too much cortisol, which in turn causes an increase in blood pressure and heart rate. This can lead to high levels of anxiety and depression.

The other benefit of getting more REM sleep is that it improves mood. When we are deprived of REM sleep for an extended period, our bodies will produce less serotonin, the neurotransmitter responsible for regulating our mood and happiness levels.

How much REM sleep should you get?

The amount of sleep you get isn't just about how much time you spend in bed. The quality of your sleep matters too. Many people oversleep while still feeling sleep deprived; these people are most likely not getting quality sleep despite sleeping for 10+ hours. 

Research has shown that the number of hours we spend in REM (rapid eye movement) sleep is essential for our mental health and physical well-being.

The number of hours we spend in REM sleep can be affected by many things, such as our age, the time we go to bed, and what we do before we go to bed.

Because it involves a lot of brain activity that causes people to dream, REM sleep is also known as "dreamy" or "paradoxical" sleep. 

An adult should get between 7-9 hours of sleep per night, but there are no hard and fast rules about how many hours of REM a person needs to be healthy.

How long does REM sleep last? 

REM sleep typically occurs after 90 minutes of sleep, lasts 10-15 minutes during the first cycle, and gradually increases in length throughout the various sleep cycles.

In the final cycle, REM sleep will last nearly an hour. 

On average, we experience four to five sleep cycles during eight hours of sleep. 

Do you dream in REM sleep?

REM sleep is the sleep stage most commonly associated with dreams.

REM-sleep is a phenomenon typically occurring during the final phase of sleep; it should not be misunderstood as the last cycle but rather as the final stage of our sleeping stages. 

During REM sleep, the brain is more active than in any other sleep stage. The brain waves are similar to those during wakefulness, and bursts of electrical activity cause the eyes to move rapidly from side to side.

The things we see and feel in our dreams are directly related to how our brains process the information they get from our senses. 

There are two types of dreams: REM and NREM. 

Dreams that occur during REM sleep are more likely to be remembered. Moreover, it is also the type that is more vivid and has more colors. 

NREM stands for Non-Rapid Eye Movement, which is less intense than REM dreams.

What are the different sleep stages?

There are four stages of sleep plus one which is an awake stage: Awake, N1, N2, N3, and REM sleep. 

Whereas the first stage, Awake, is not considered a sleep stage because you are not truly asleep.

NREM sleep (non-rapid eye movement) is classified as stages N1–N3, with progressively more deep sleep in each stage.

The NREM stages account for approximately 75% of total sleep time, with the N2 stage accounting for the majority of total sleep time.

A typical night's sleep consists of four to five sleep cycles, with the stages of sleep proceeding in the following order: N1, N2, N3, N2, REM.

A complete sleep cycle lasts approximately 90 to 120 minutes.

The first REM period is brief, but as the night goes on, longer REM periods and less time in deep sleep (NREM) occur. 


The first stage is the wake stage, also known as stage W, and it is determined by whether the eyes are open or closed. 

N1 - (Stage 1) Light sleep

Stage 1 is a light sleep state in which surroundings can quickly awaken the sleeper. This stage lasts for about 1 to 10 minutes, and then the brainwaves become more synchronized with each other, and the sleeper enters N2.

N2 - (Stage 2) Deeper Sleep 

You will enter a deeper sleep state as your heart rate and body temperature decrease. Stage 2 is a deeper sleep state where the sleeper is unaware of their surroundings. Stage 2 sleep lasts approximately 25 minutes in the first cycle. It gradually increases in length with each subsequent cycle, eventually accounting for roughly 45 percent of total sleep.

N3 - (Stage 3) Deep Sleep

Deep Sleep is also known as SWS. 

Slow-wave sleep (SWS)​3​ is the deepest phase of non-rapid eye movement (NREM) sleep. Stage 3 sleep The deep sleep stage is the most challenging stage to awaken from; for some people, even loud noises (greater than 100 decibels) will not wake them up.

People tend to spend less time in deep sleep and more time in stage 2 as they age. Deep sleep is the stage during which the body repairs and regrows tissues, builds bone and muscle, and fortifies the immune system.

Sleepwalking, night terrors, and bedwetting are also common at this stage. 

REM Sleep - Stage 4

The next stage is called REM or Rapid Eye Movement Sleep, where brain activity increases markedly. Dreams occur during this phase because it is when brain waves are most active and similar to wakefulness. This stage typically begins 90 minutes after falling asleep, with each REM cycle getting longer throughout the night.

The first period is usually 10 minutes long, and the last one can last up to an hour.

Dreaming and nightmares occur during REM. 


How do I know if I am getting enough REM sleep?

Spending 20-25 percent of your sleep time in the REM stage is a good goal for healthy adults.

If you sleep for 7-8 hours, 90 minutes of that time should be REM.

The standard amount of REM sleep also decreases with age, beginning in infancy (when it may account for more than 50% of total sleep time) and continuing through adulthood. 

How do you measure REM sleep?

There are many ways to measure REM sleep, but an EEG(electroencephalogram) is the most common. The device measures electrical activity in the brain. It converts this into information about when you are in different stages of sleep.

What is an EEG? An electroencephalogram (EEG) is a doctor-administered test that measures the activity in your brain. There are many different EEG types, but the most common and easy to use is an event-related potentials (ERP) EEG.

What can I do to get enough sleep?

How many hours of sleep should I get? 

The average adult needs between seven and nine hours of sleep each night. You could spend a lot of time doing other things, so getting the right amount is essential.

The National Sleep Foundation recommends that adults ages 18-64 get seven to nine hours of sleep daily. This amount varies depending on your age and how active you are during the day.

If you feel sleepy during the day and your work performance declines, it may be time to reevaluate your sleep habits. You may not get enough sleep at night, or you may not get enough quality REM sleep time during the night.

Lack of REM sleep can lead to many health problems such as depression, weight gain, and memory loss.


REM sleep is the most crucial sleep stage. It changes every few minutes and is characterized by rapid eye movements and dreaming. Every 90 to 120 minutes, we switch between REM and non-REM sleep.

The human brain is a complex organ that needs to be regulated to function correctly. Sleep is the best way to regulate your brain, so take naps if necessary.

According to science, getting more REM sleep can have several benefits. It can reduce stress, improve mood, and make you more productive.

REM sleep, also known as dream sleep, is a unique sleep stage because the brain is more active than any other sleep stage.

Brainwaves are similar to those experienced while awake, and rapid eye movement causes them to shift from side to side. 

  1. 1.
    Blumberg M, Lesku J, Libourel P, Schmidt M, Rattenborg N. What Is REM Sleep? Curr Biol. 2020;30(1):R38-R49. doi:10.1016/j.cub.2019.11.045
  2. 2.
    Patel A, Reddy V, Araujo J. statpearls. Published online April 28, 2022. http://www.ncbi.nlm.nih.gov/books/NBK526132/
  3. 3.
    Zolovska B, Shatkin JP. Key Differences in Pediatric versus Adult Sleep. Encyclopedia of Sleep. Published online 2013:573-578. doi:10.1016/b978-0-12-378610-4.00496-4
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