Understanding Rapid Eye Movement: Rem Sleep Explained

Rapid Eye Movement (REM) sleep is one of the four stages of sleep. It is characterised by rapid movement of the eyes, low muscle tone, and the likelihood of the sleeper to dream vividly. The core body and brain temperatures increase during REM sleep, while the skin temperature decreases. The REM phase is also known as paradoxical sleep (PS) due to its physiological similarities to waking states, including rapid, low-voltage desynchronised brain waves.

REM sleep is characterised by rapid eye movement, irregular breathing, and increased brain activity

REM sleep, or rapid-eye-movement sleep, is one of four stages of sleep. It is characterised by rapid eye movement, irregular breathing, and increased brain activity.

During REM sleep, the body and brain undergo several changes. The eyes move rapidly in various directions, and the brain's electrical activity increases, resembling the brain's activity when awake. The brain's increased activity can lead to vivid dreams. The body experiences a temporary loss of muscle tone, and the heart rate increases. Respiration becomes irregular, and blood pressure rises.

REM sleep is important for several reasons. It is associated with dreaming and memory consolidation. It also plays a role in emotional processing, brain development, and wakefulness preparation. Most adults need about two hours of REM sleep each night.

The first cycle of REM sleep typically occurs within 60 to 90 minutes of falling asleep. As the sleep cycle repeats, REM sleep occurs several times throughout the night, accounting for approximately 20-25% of an adult's sleep cycle and over 50% of an infant's.

The transition into REM sleep is marked by electrical bursts called "ponto-geniculo-occipital waves" (PGO waves) originating in the brain stem. The extraocular movements for which REM sleep is named are largely due to the cholinergic activity of the pedunculopontine tegmentum (PPT) centre and the glutamatergic activity of the medial pontine reticular formation (mPRF).

It is the fourth stage of sleep and is also known as paradoxical sleep

Rapid Eye Movement (REM) sleep is the fourth and final stage of sleep. It is also known as paradoxical sleep, as well as active sleep, desynchronized sleep, rhombencephalic sleep, and dream sleep.

REM sleep is characterised by relaxed muscles, quick eye movement, irregular breathing, elevated heart rate, and increased brain activity. The brain activity during REM sleep is similar to that of a waking brain, and dreams typically occur during this stage. The eyes move rapidly behind closed eyelids, and the body experiences a temporary loss of muscle tone. This is thought to be a protective measure to prevent sleepers from acting out their dreams and injuring themselves. However, this hypothesis is being challenged by the discovery that dreams can also occur during non-REM sleep.

REM sleep is important for memory consolidation, emotional processing, brain development, and dreaming. It is also believed to be essential for brain development in infants, who spend most of their sleep time in this stage.

The first cycle of REM sleep occurs around 60 to 90 minutes after falling asleep. A full night's sleep involves cycling through four stages of sleep multiple times: three stages of non-REM sleep, followed by one stage of REM sleep. Each cycle takes 90 to 120 minutes to complete, and as the cycles repeat throughout the night, the amount of time spent in REM sleep increases.

The transition from non-REM to REM sleep brings marked physical changes, beginning with electrical bursts called ponto-geniculo-occipital waves (PGO waves) originating in the brain stem. During REM sleep, the body abruptly loses muscle tone, a state known as REM atonia.

REM sleep is physiologically different from non-REM sleep, which is characterised by slower brain waves and partial muscle tone. Non-REM sleep is further divided into three stages: light sleep, light sleep, and deep sleep.

It is associated with dreaming, memory consolidation, and emotional processing

REM sleep is associated with dreaming, memory consolidation, and emotional processing. Dreaming is perhaps the most well-known aspect of REM sleep. During this stage, the brain is highly active and dreams are usually more vivid. While dreaming also occurs during non-REM sleep, the dreams experienced during REM sleep are typically more intense and narrative in structure.

Memory consolidation is another important function of REM sleep. The brain processes and consolidates new information and memories during this stage. Research has shown that sleep deprivation can negatively impact memory and cognitive function, highlighting the importance of adequate REM sleep for learning and memory retention.

Additionally, REM sleep plays a role in emotional processing. The amygdala, the part of the brain responsible for processing emotions, is active during this stage. Dreams during REM sleep may be involved in emotional processing, as they can be more vivid and incorporate emotional themes.

The functions of REM sleep are not fully understood, and researchers continue to explore its role in brain development, learning, and mood regulation.

A lack of REM sleep may negatively impact physical and mental health

REM sleep is a unique phase of sleep characterised by random rapid movement of the eyes, low muscle tone, and vivid dreams. It is thought to be important for brain development, learning, memory, and mood.

In addition, REM sleep deprivation can cause mild psychological disturbances, such as anxiety, irritability, hallucinations, and difficulty concentrating. It can also increase appetite and aggression, and disrupt eating behaviour. While the long-term effects of REM deprivation are still unknown, some studies have indicated that it can increase aggression and sexual behaviour in laboratory animals, with rats deprived of paradoxical sleep dying within four to six weeks.

Overall, a lack of REM sleep appears to have negative consequences for both physical and mental health, highlighting the importance of getting sufficient, high-quality sleep.

REM sleep is important for brain development, especially in infants

Rapid eye movement (REM) sleep is a unique phase of sleep in humans and other mammals, characterised by random rapid movement of the eyes, low muscle tone throughout the body, and the tendency to dream vividly. The brain is highly active during REM sleep, and brain activity is similar to its activity when awake.

Newborns spend close to equal amounts of time in REM and non-rapid eye movement (NREM) sleep. As a baby grows, their sleep cycles progress, and they begin to spend less time in REM sleep, and more time in the three stages of NREM sleep. By adulthood, people experience REM sleep for roughly 20% of each night's sleep, which is far less than the 50% of sleep newborns spend in REM.

REM sleep plays a role in memory consolidation, emotional processing, and dreaming, in addition to brain development. During REM sleep, the brain processes new learnings and motor skills from the day, committing some to memory, maintaining others, and deciding which ones to delete.

Frequently asked questions