REM Sleep: What Is It?

One of the four phases the brain experiences throughout the sleep cycle is rapid eye movement sleep, or REM sleep. Numerous physiological changes are indicative of it, such as relaxed muscles, higher brain activity, eye movement, and rapid breathing.

This stage of the sleep cycle typically occurs ninety minutes after the person goes to sleep. Usually, REM sleep cycles last between ninety and one hundred minutes. REM sleep accounts for around 25% of a person’s entire sleep duration.

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Although the Centers for Disease Control and Prevention (CDC) recommend that individuals get between seven and eight hours of sleep every night, this depends on their age. You should spend around 120 minutes a night in REM sleep as it makes up roughly 25% of your entire sleep.

The symptoms and implications of REM sleep are covered in this article. It also looks at various actions you may do to enhance your quality of REM sleep.

REM Sleep Indications

Several changes that are typical of this stage of sleep occur in the body and brain. Important indicators of REM sleep include:

Variations in body temperature

twitching of the body, especially in the arms, legs, and face

elevated blood pressure

elevated brain activity comparable to that of conscious states

elevated heart rate

increased brain oxygen consumption

jerky eye motions

Breathing too quickly or irregularly

Arousal sexually

A common side effect is atonia, which is a transient paralysis. The muscles that immobilize the body during REM sleep activate, briefly paralyzing the person. This keeps you from physically enacting out your dreams and is a typical effect of REM sleep.

NREM versus REM sleep

The distinct eye movements and brain wave patterns that identify REM and NREM sleep allow for their differentiation. Rapid eye movements, elevated brain activity, and suspension of homeostasis are characteristics of REM sleep. Three separate phases of NREM sleep are distinguished by progressively slower brain waves.

The physiological distinctions between REM and NREM sleep are also significant. Acetylcholine secretion and reduced serotonin and other monoamine synthesis are what trigger REM sleep.

Does REM Sleep Occur When?

Sleep occurs in four distinct phases. The first three phases of sleep are accounted for by NREM, whereas REM sleep is thought to be the fourth stage.

Phase 1: The phase of NREM sleep that begins with falling asleep is known as this. During this stage of sleep, the body relaxes more and the brain slows down. This is a relatively quick stage that lasts around five minutes.

Stage 2: Brain waves and bodily activity both slow down during this phase of sleep. People sleep in stage 2 sleep for around half of the night. Usually, this phase lasts for ten to sixty minutes.

Stage 3: This stage, sometimes referred to as deep sleep, is characterized by slower brain waves and bodily movements. Sleeping at this time is crucial for learning and memory. Stage 3 often lasts between 20 and 40 minutes.

Stage 4: REM sleep, during which the body and brain become more active, rapid eye movements start, and dreaming takes place.

It’s crucial to remember that when you sleep, these phases don’t always happen in the same order. Stages 1, 2, and 3 take place in the initial sequence, after which stage 2 recommences. When stage 2 sleep occurs a second time, REM sleep initially manifests.

A whole sleep cycle takes around one hour to finish. A person may have four to five cycles every night, depending on how long they sleep for.

Effects of Rapid Eye Movement

In addition to its involvement in mood, dreaming, and memory, REM sleep is crucial for brain growth.


During the rapid eye movement (REM) phase of sleep, dreams take place. Your dreams last two hours on average each night, divided by your sleep cycle.

The precise causes of human sleep are not entirely understood by researchers. They are aware that rats who are deprived of REM sleep have much shorter lifespans and that babies dream. Fish, turtles, and lizards are examples of cold-blooded creatures that do not experience REM sleep periods, while other mammals and birds do.

Mental Development

According to research, REM sleep is critical for the early development of the central nervous system (CNS). Developing and enhancing synaptic connections may be aided by the brain’s high levels of activity during this sleep phase.


It’s possible that the brain uses dreams to organize memories. The brain may be able to analyze and restructure the day’s events during dream time, as well as make connections between new and past experiences. The brain can accomplish this without needing further input or running the risk of the body “acting out” the memories of the day since the body is shut down.

According to some academics, dreams are more akin to structured and interpreted background “noise.” According to the activation-synthesis idea, dreams are only the brain’s effort to interpret haphazard impulses that happen while we sleep.

Processing Emotions

It is also thought that REM sleep is crucial for processing emotions. Dreaming might contribute to this procedure. Studies indicate that insufficient sleep is linked to impaired encoding of emotional memory and reduced consolidation of emotional memory.