REM Sleep

Written by Ashima Yadav

Last Updated June 13, 2024

kaneesha allen Fact checked by Kaneesha Allen

Most of us have heard the term ‘REM sleep’ somewhere or another, maybe while searching for better sleep habits or while simply browsing out of curiosity. If you're conscious of your sleeping habits and sleep quality, you must be wondering what REM sleep is, why it is so important, and how to improve it. Don't worry! We are here to put a full stop to all your queries and answer them all on this one blog.

what is REM sleep

Your brain passes through four stages of sleep, one of which is rapid eye movement (REM) sleep. It is characterized by a number of physiological changes, like muscle relaxation, quicker breathing, relaxed eyes, and elevated brain activity. The main characteristic of this stage, however, as the name suggests, is rapid side-to-side eye movement.

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People usually enter the REM stage within 90 minutes of falling asleep, which reoccurs several times during sleep duration. REM constitutes approximately 25% of an adult's sleep. Therefore, considering that an adult needs about 8 hours of sleep, one should spend 2 hours or 120 minutes in REM sleep every night.

REM and NREM sleep - What's the difference?

During NREM sleep, the body progressively relaxes, restores energy, and works on healing itself. On the other hand, during REM sleep, there is an increase in brain activity, faster and irregular breathing, and rapid eye movement. NREM sleep accounts for 75% - 80% of a person's total sleep, while REM accounts for about 20% - 25% of the sleep.

Stages of sleep

A person goes through three NREM stages of sleep before finally entering the REM stage of sleep. Here, we first take a look at each of these stages in detail:

an infographic chart showing stages of sleep.

Stage 1: Very light sleep, NREM stage

This stage of sleep lasts for around 5 to 10 minutes. During this stage, the brain is still relatively active and producing high amplitude (high voltage but low in frequency, 3.5-4.5 Hz) theta waves, which are slow brain waves occurring primarily in the brain's frontal lobe. This stage is considered the border between waking and sleeping. It is characterized by the slowing down of brain activity, heartbeat, eye movements, and breathing. Your body relaxes during this stage, and your muscles may twitch.

Stage 2: Light sleep, NREM stage

This stage lasts for about 20 minutes. During this stage, your awareness level reduces, your body temperature drops, your eye movements stop, and your breathing and heart rate become more regular. This stage is also characterized by bursts of rapid and rhythmic brain wave activity, known as sleep spindles (12-14 HZ). They occur 2 to 5 times per minute. They are said to be a feature of memory consolidation.

Stage 3: Deep sleep/ Slow wave sleep, NREM stage

This is a deep sleep stage during which your muscles are completely relaxed, blood pressure drops, breathing slows, and you progress into your deepest sleep. In this state of deep sleep, any environmental noises or activity may fail to wake you. During this stage, your body also starts its physical repairs. Therefore, getting enough deep sleep allows you to feel refreshed the next day. This sleep is also characterized by deep, slow brain waves known as delta waves.

Stage 4: REM stage

REM sleep starts approximately 90 minutes after falling asleep. During REM sleep, your brain lights up with activity, your body gets relaxed and immobilized, your breathing is faster and irregular, your eyes move rapidly, and most people dream during this stage. While your brain is aroused with mental activities during REM sleep, your voluntary muscles become immobilized, which abstains you from acting out your dreams.

It's crucial to understand that these phases don't always occur in any set order as you sleep. Stages 1, 2, and 3 occur in the first sequence before stage 2 starts over again. REM sleep first occurs after this second occurrence of stage 2 sleep. A complete sleep cycle lasts approximately 100 minutes. Depending on how much sleep one gets, four to five sleep cycles may occur every night.

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Functions of REM sleep

REM sleep plays an integral role in various physiological functions like brain development, dreaming, and emotional processing.

1. Brain Development

REM sleep is essential for the development of the central nervous system (CNS), especially in infants. This is explained by the fact that the duration of REM sleep is longer in babies than in adults, and it decreases with age. Moreover, animals born with less developed brains, like humans and puppies, spend more time in REM sleep during infancy than those born with more developed brains, like horses and birds.

Research indicates that the higher level of brain activity during REM sleep plays a role in neural stimulation essential for the development and strengthening of neural connections for mature structural development of the brain.

2. Dreams

The majority of dreams take place in REM sleep, and the dreams one experiences during this stage of sleep are more vivid and frequent. It's common for us to think that we didn't have any dreams if we don't remember any in the morning. However, dreams occur every night. On average, you dream for two hours per night, with the sleep cycle serving as a break.

3. Learning and Memory

There are several theories as to why we dream, and one of them is the information-processing theory. This theory suggests that dreams are a part of cognitive development and help the brain with memory consolidation. In addition, this theory suggests that we organize our memories as we sleep and convert short-term memory into long-term memory. Our dreams, which often contain elements of what we experienced that day, are a byproduct of that process.

Another theory, the physiological-functioning theory, suggests that dreams help preserve neural pathways. According to this theory, brain activity during sleep keeps us functioning and ready to process information when we wake up the following day.

4. Emotional Processing

The Amygdala, part of the brain that processes emotions, is activated during REM sleep. Therefore, this stage of sleep plays an essential role in emotional processing. It is also believed that dreams, especially vivid ones, are involved in the process. Research shows that lack of sleep leads to poor memory consolidation and poor encoding of emotions and emotional memory.

Consequences of lack of REM sleep

Since REM sleep plays an important role in a lot of essential physiological functions like brain development and memory consolidation, insufficient REM sleep can result in some problems. A lack of REM sleep can have adverse effects on physical as well as mental health.

1. Learning and Memory

The areas of the brain that are activated during REM sleep play a significant role in memory consolidation. Therefore, not getting enough REM sleep can have a substantial impact on one's memory and learning power.

A study from 2016 showed that a lack of sleep could increase the risk of forming false memories. Moreover, when people are taught new skills and then deprived of REM sleep, they frequently find it challenging to recall what they were taught.

2. Central Nervous System Development

Since REM sleep plays a crucial role in CNS development, a lack of REM sleep affects brain development. In addition, sleep deprivation can cause disruptions in neural pathways, leading to issues in cognitive tasks such as decision-making.

3. Obesity

Sleep deprivation is associated with changes in leptin levels. Leptin is a hormone that helps your body maintain its average body weight. Even if your body has enough fat reserves, leptin resistance makes you feel hungry. This results in over-eating and gaining weight.

Sleep disorders associated with REM sleep

sleep behavior disorder

REM sleep issues can arise from a variety of different sleep disorders. The majority of people occasionally have sleep issues. However, you may have a sleep disorder if:

  • Your capacity to engage in typical daytime activities is diminished or impeded
  • You have trouble staying awake when doing something passive, like watching TV or reading
  • You have difficulty paying attention or concentrating at work, school, or home
  • You experience performance problems at work or school
  • You face difficulty with your memory
  • You have slowed responses
  • You have difficulty controlling your emotions

REM Sleep Behavior Disorder (RBD)

One important characteristic feature of REM sleep is that the nerve pathways in the human brain that prevent muscles from moving remain active. However, people suffering from REM sleep behavior disorder do not experience this muscle paralysis. Not experiencing this muscle paralysis results in them enacting their dream. Any simple, dramatic, or violent dream can be enacted by people experiencing RBD. Therefore, this disorder poses a threat to the person themselves and to people around them. It also prevents them from getting restful sleep.


Narcolepsy is a condition wherein a person experiences excessive daytime sleepiness and sudden sleep attacks. There are two types of narcolepsy. Type 1 narcolepsy is accompanied by cataplexy, a sudden loss of muscle tone, which can be triggered by strong emotions. People with narcolepsy face disruptions in their daily lives.

Nightmare Disorder

Nightmares occur during REM sleep and are disturbing dreams associated with feelings of anxiety or fear that wake you up. While we all experience unpleasant dreams once in a while, it becomes a nightmare disorder when these unpleasant dreams occur frequently and cause distress and fear of sleeping.

Sleep Apnea

Although sleep apnea does not just occur during REM sleep, it also impacts how much REM sleep a person gets. People with sleep apnea have breathing problems when they are asleep. When this occurs during REM sleep, they frequently transition to a lighter sleep cycle to continue breathing. Consequently, they spend less time in REM sleep and have excessive daytime tiredness.

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How to improve REM sleep

Understanding sleep disorders as well as following the below mentioned healthy sleeping habits may help increase the quality of both REM and non-REM sleep.

1. Sleep Schedule

The daily routine of going to bed and getting up at the same time helps your body's biological clock get in sync with it and helps you get a good night's sleep. In addition, following a sleep schedule will increase your overall sleep quality, including REM sleep.

2. Get Enough Sleep

A healthy adult requires about 7-8 hours of sleep per night. If one gets less sleep, it also reduces the time one spends in REM sleep. Therefore, to improve the quality of your sleep, you need to prioritize and catch enough sleep.

3. Avoid Alcohol Intake

Research shows that moderate to high levels of alcohol consumption before bedtime delay the onset of REM sleep as well as reduce the number of REM phases experienced. Therefore, avoiding alcohol before bedtime will go a long way toward improving your sleep quality.

4. Address Medical Conditions

Any medical condition, like sleep apnea, restless leg syndrome, REM sleep disorder, etc., that causes a hindrance to your sleep quality should be addressed. Consult your doctor regarding these issues, and taking care of them can enhance the quality of your sleep to a great extent.

REM sleep is very crucial for us, so it's important that we get enough of it every night. Your enhanced knowledge about REM sleep will help you sleep better, and you can also use the above mentioned tips to have a good night's sleep. However, if you have trouble sleeping or have disrupted sleep, then it is best to consult your doctor.

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Disclaimer: What is said in this article has been referenced from multiple sources and is intended only for educational and informational purposes. Please note that no content in this article is a substitute for professional advice from a qualified doctor or healthcare provider. Always consult an experienced doctor with any concerns you may have regarding a health condition or treatment, and never disregard any medical suggestions or delay in seeking treatment because of something you read here.