July 25, 2024

Rapid eye movement (REM) sleep is a stage of sleep. With a lack of REM sleep, symptoms emerge that can affect your health. It can lead to fatigue, irritability, changes in mood and memory, and issues with cognition and problem-solving. In some cases, medication (like antidepressants) may affect REM sleep quality and quantity.

A lack of REM sleep leads to physical symptoms, too, consistent with sleep deprivation in general. It can affect cardiovascular health and increase the risk of type 2 diabetes. It may also contribute to cancer, stroke, and neurodegenerative diseases like Alzheimer’s.

This article explains what REM sleep is and why it is important. It details the causes of a lack of REM sleep, symptoms common with REM sleep deprivation, and ways to increase REM sleep.

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What Is REM Sleep?

Rapid eye movement (REM) sleep is one of the two major natural sleep stages. It is so distinct that the other stages in the four cycles of sleep are sometimes grouped together as “non-REM sleep.” It occurs in four to six short cycles, beginning about 90 minutes after you fall asleep and often increasing toward the end of sleep time.

The brain is active during REM sleep. Most muscles, including skeletal muscles, are paralyzed during this phase of sleep, except those used for eye movement and breathing. Skeletal muscles are the muscles that control voluntary movements like walking.

Vivid dreams are another core part of REM sleep, though dreaming occurs across all sleep stages for a total of about two hours.

Paralysis may prevent you from acting out your dreams. Without this paralysis, REM sleep behavior disorder can happen. People with this condition act out their dreams during sleep.

The brain activity in REM sleep and other cycles can be measured in sleep studies (polysomnogram) that use different tools to measure sleep activity. These include:

  • Electroencephalogram (EEG) to measure brain waves
  • Electromyogram (EMG) to measure muscle activity
  • Electrooculogram (EOG) to measure eye movement

Functions of REM Sleep

Research is not conclusive, but it suggests that REM sleep is important for daytime function and wakefulness. It may help you learn and consolidate your memories.

REM sleep is thought to be helpful for procedural memory. This is the type of memory you use when you learn a new skill, like how to ride a bike. It differs from factual or semantic memory. This is the type of memory you use for something like dates or lists of facts.

REM sleep may also help you solve problems. During REM sleep, you may make unique connections within your brain. In newborns, REM sleep contributes to brain development.

REM sleep is characterized by other biological changes. During REM sleep:

  • Breathing speeds up
  • Heart rate increases
  • Blood pressure rises
  • The eyes, although closed, move rapidly beneath the lids
  • Males have erections
  • Body temperature falls to the lowest point of the day or night

During REM sleep, you have vivid dreams. They may unfold like a movie in which you are an actor. When the content of a dream is disturbing, you may experience it as a nightmare. Some experts believe changes in brain wave activity paired with an increase in the firing of nerve cells (neurons) in the brain during REM sleep contribute to dreaming.

How Much REM Sleep Do You Need?

Sleep occurs in cycles, with a rapid eye movement (REM) sleep stage about every 90 to 120 minutes. An adequate night’s sleep for an adult is about seven or eight hours. A healthy young adult will spend about 20% to 25% of the total sleep time in REM sleep states.

Lack of REM Sleep Symptoms

When you experience a lack of REM sleep, symptoms can include fatigue, and problems with memory and other cognitive tasks during the day. You may even have brief microsleep episodes (nodding off during the day), which can occur with sleep deprivation in general.

Some studies demonstrate a relationship between REM sleep disruptions (how long it takes for REM sleep to start, its duration, the frequency of the stages) and certain types of depression. Symptoms of depression may be linked to REM sleep.

Over time, sleep deprivation can contribute to a number of health conditions, like obesity and metabolic disorders that increase the risk of sleep apnea. Sleep apnea can be treated with continuous positive airway pressure (CPAP) therapy, and effective sleep apnea treatment can help REM sleep rebound.

What Causes a Loss of REM Sleep?

Sleep deprivation has real impacts on health and well-being. The most obvious is sleepiness. Feeling sleepy can affect your work and family life. It can also make it dangerous to do things like drive a car.

Sleep deprivation contributes to health issues, such as heart health. It also affects physical symptoms, including the ability to tolerate pain and your sensitivity to it.

Causes of a lack of REM sleep, or conditions that may contribute to symptoms, include:

Substance use has a strong impact on REM sleep. The following are known to suppress REM sleep:

Medications also affect REM sleep, including:

Brain Function, Dreams, and REM Sleep

Certain parts of the brain are especially active in REM sleep function, including the amygdala, the thalamus, the pons, and medulla of the brain stem. The thalamus sends out images, sounds, and other elements that are part of dreaming. They can be affected by brain changes.

Health Effects

The purpose of REM sleep is still unknown. It’s difficult, therefore, to assess the health effects of dream deprivation apart from all other effects of sleep deprivation.

Subjects with permanent damage to the REM-related part of the brain can seem unaffected by the loss of REM sleep. These subjects may have normal memory and no loss of function.

However, mood disorders can change the experience of dreams (for example, having more nightmares). The same brain mechanisms at work in anxiety disorders are highly active during REM sleep, for example, and changes in REM sleep patterns may contribute to more disturbed dreaming.

When to See a Healthcare Provider

You may want to see a healthcare provider if you are experiencing general symptoms of sleep deprivation, such as:

  • Falling asleep quickly, as soon as a few minutes after your head hits the pillow
  • Daytime drowsiness
  • Microsleeping

You may want to be evaluated for a sleep disorder. It also may be important to have your symptoms evaluated for another diagnosis, such as sleep apnea or anxiety.


Rapid eye movement sleep is the sleep stage associated with dreaming. During this stage, your brain is active and your muscles are relaxed. Sleep has structure, called architecture, and REM sleep happens at regular intervals during the sleep period. This is typically every 90 to 120 minutes.

Scientists don’t yet understand why we need REM sleep. It may be important for memory and daytime function. The long-term effects of dream deprivation are unknown, and more research is needed into the effects of REM sleep deprivation.

Many factors can influence how much REM sleep you get. Substance use and sleep disorders like sleep apnea can all have an effect. If you’re worried about REM sleep deprivation, contact a board-certified sleep physician. Ask about the benefits of a diagnostic sleep study.


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