Chin Movement And Rem Sleep: What's The Connection?

REM sleep is a fascinating phenomenon that has puzzled scientists for decades. During this stage of sleep, the body experiences temporary paralysis from the chin down, with the exception of the diaphragm and the heart. This paralysis is thought to be a protective measure to prevent people from acting out their dreams and injuring themselves. However, in some cases of REM sleep behaviour disorder (RBD), people do not experience this paralysis and may act out their dreams, potentially harming themselves or their bed partner. While the purpose of REM sleep is not fully understood, it is believed to play a crucial role in memory consolidation, emotional processing, brain development, and dreaming.

Dreaming is common during REM sleep

During REM sleep, your eyes move rapidly behind closed eyes, your heart rate speeds up, and your breathing becomes irregular. Your brain is highly active during REM sleep, and your brain waves are more variable. In contrast, during other stages of sleep, your brain waves slow down.

The first cycle of REM sleep occurs about 60 to 90 minutes after falling asleep. As part of a full night's sleep, you cycle through four stages of sleep multiple times: three stages of non-REM sleep, followed by one stage of REM sleep. Each cycle through all the sleep stages takes 90 to 120 minutes to complete. With each new cycle, you spend increasing amounts of time in REM sleep, with most of your REM sleep taking place in the second half of the night.

REM sleep is important for several reasons. Firstly, it is associated with dreaming, memory, emotional processing, and healthy brain development. Secondly, it plays a role in memory consolidation, which is the process of committing new learnings and motor skills from the day to memory. Thirdly, it is involved in emotional processing, as your brain processes emotions during REM sleep, and your amygdala, the part of your brain responsible for processing emotions, is activated during this stage. Finally, REM sleep may promote brain development, as newborns spend most of their sleep time in REM, and animals born with less developed brains spend more time in REM sleep during infancy.

While dreaming typically occurs during REM sleep, it is important to note that dreams can also occur during non-REM sleep stages. However, the dreams experienced during REM sleep tend to be more vivid and intense.

Memory consolidation occurs during REM sleep

During REM sleep, the body behaves in a manner similar to when it is awake. The eyes move rapidly behind closed eyelids, the heart rate speeds up, and breathing becomes irregular. The brain is highly active during REM sleep, and brain waves become more variable. This is the stage of sleep where most dreams occur, and it is characterised by relaxed muscles, quick eye movement, irregular breathing, elevated heart rate, and increased brain activity.

REM sleep is important for memory consolidation, emotional processing, brain development, and dreaming. Memory consolidation refers to the process by which the brain processes new learnings and motor skills from the day, committing some to memory, maintaining others, and deciding which ones to delete. Researchers have found that activity in adult-born neurons (ABNs) in the hippocampus, a brain region associated with memory, is responsible for memory consolidation during REM sleep.

The presence of dreaming during REM sleep indicates that memory formation may occur during this sleep stage. Researchers from the University of Tsukuba and the University of Tokyo found that ABNs in the hippocampus are responsible for memory consolidation during REM sleep. ABNs in the dentate gyrus region of the hippocampus are rare and not frequently active, but they show heightened plasticity, indicating their potential role in the formation of memories.

During sleep, the body "powers down" and most body systems, including the brain, become less active. However, the brain remains active and reorganises and catalogues memories and learned information. This process of brain maintenance makes it easier to access and retrieve learned information.

While it is true that muscle paralysis occurs during REM sleep to prevent people from acting out their dreams, this is not the case for those with REM Sleep Behaviour Disorder (RBD). People with RBD act out their dreams and may shout, punch, kick, or grab things or people around them, potentially causing injury. RBD may be caused by a breakdown in the area of the brainstem responsible for regulating REM sleep.

Emotional processing occurs during REM sleep

REM sleep is when you tend to have vivid dreams. You have several REM cycles per night. The first REM cycle begins about 90 minutes after you fall asleep and lasts about 10 minutes. Each REM cycle that follows gets longer and longer.

REM sleep deprivation is followed by the rebound of rapid eye movement sleep and slow wave sleep in the following nights. This effect suggests that a certain amount of REM-sleep and SWS is crucial in sleep. Clinical evidence suggests that sleep has a role in regulating our emotional brain-state since sleep impairment corresponds to affective dysfunction.

REM sleep dreaming plays a crucial role in modulating people's emotions. In a review, Payne & Nadel concluded that dream content varies as a function of sleep stage and time of night. Dreams seem to be more vivid and emotionally colorful during REM-sleep in comparison with dreams in other sleep stages where they have been found more of a thought-like cognitive nature. In REM-sleep, mentation has been found to be more expressive of motives and emotions. Moreover, the product of this culmination of emotions may result in nightmares during REM-sleep and NREM-sleep, in which negative emotional experiences are decreased, resulting in favorable “therapeutic” outcomes and compensating effects of emotion regulation failure in the daytime.

REM-dreaming functions as a central phase of the masked or unmasked reactivation and the reprocessing of emotions and emotional occurrences during the day. Dream production, especially in REM-sleep, which contains vivid simulations of painful and threatening events within real life, facilitates the processing of distressing emotions. Even more, it has been assumed to have a role in integrating traumatic and other distressing moments into our long-term memory. Changes in motivation and emotion are aspects in mood disorders, which are related with alterations in limbic processing not only during daytime, but also during REM-sleep. Every reprocessing of negative stressful events visually appearing in altered visualizations of what has happened in the day in dreaming may function to integrate negative experiences into long-term memory in order to be prepared for future negative experiences.

Earlier REM-sleep onset and higher dream activity in the initial REM-period, have even been found to predict a greater reduction of the depressive symptoms after a distressing life event. It aids the processing of negative information making aversive events bearable. In particular, intensification of phasic REM-sleep appears to be a marker of dysfunctional or too little emotion regulation during the day indicating the need of further emotion processing and emotion regulation during sleep.

In summary, abundant evidence confirms a relationship between the emotional events we experience during the day and changed sleep physiology. Although consistent knowledge about stress can elicit profound and lasting effects on sleep, the pathways in stress affecting sleep are not well understood. Some research evidence has showed how the medial prefrontal cortex might play an important role in easing the detrimental effects of stress on sleep via the mediating activity of brain areas involved in the stress response such as the hypothalamus, the locus coeruleus and the limbic system. Looking at the discussed findings, we notice an enhanced effective emotional adjustment and amelioration of mood and well being after intact sleep, especially REM-sleep. Good sleep may work as a bio-behavioral regulatory and restorative process that regulates daily emotional experiences and allostatic load of emotional stress. Future research should pay attention to the pathways in which stress affects sleep. Of importance is how affected sleep physiology exerts further influence on following emotion processing.

Brain development occurs during REM sleep

During REM sleep, the brain enters a state of high activity, resembling the brain activity of a waking person. This stage of sleep is crucial for brain development, especially in newborns and infants, as it promotes the formation and maintenance of neural connections necessary for cognitive, behavioural, and emotional growth.

REM sleep is characterised by rapid eye movements, increased brain activity, irregular breathing, and a temporary loss of muscle tone. While the body remains relaxed, the brain is highly active, processing emotions and consolidating memories. This stage of sleep is also associated with dreaming, and the dreams that occur during REM sleep tend to be more vivid than those during non-REM sleep.

The role of REM sleep in brain development is supported by the fact that newborns spend a significant amount of their sleep in this stage. Additionally, species born with less developed brains, such as humans and puppies, spend a greater proportion of their sleep in REM compared to species born with more developed brains, such as horses and birds. This suggests that REM sleep plays a crucial role in the development and maturation of the brain, particularly in the early stages of life.

The brain's increased activity during REM sleep is hypothesised to promote brain development and maturation. This is especially important for newborns and infants, whose brains are rapidly developing and forming new neural connections. The duration and proportion of REM sleep change as individuals age, with adults requiring less REM sleep than infants. This decrease in REM sleep across the lifespan may be related to the brain's reduced need for intense developmental processes as it matures.

The function of REM sleep in brain development extends beyond humans. Animal studies have shown that rats who learned to navigate a maze spent more time in REM sleep for nearly a week afterward, indicating that REM sleep plays a role in memory consolidation and learning.

REM sleep is associated with sleepwalking

Sleepwalking, or somnambulism, is a sleep disorder that occurs during deep, non-REM sleep, usually in the first half of the night. Sleepwalking involves walking or performing other complex behaviours while still asleep. While sleepwalking is distinct from REM sleep behaviour disorder (RBD), the two conditions share some similarities.

During REM sleep, the eyes move quickly behind closed eyelids, and vivid dreaming is most common. REM sleep behaviour disorder is a condition in which individuals act out their dreams, often involving a wide range of movements. Unlike sleepwalking, individuals with RBD can recall their dreams upon waking. However, both conditions can result in similar movements, such as jumping or kicking, which can potentially cause harm to oneself or one's bed partner.

Sleepwalking is more common in children and young adults than in older adults. This is because older adults experience less deep, non-REM sleep. Sleepwalking tends to run in families, with a strong genetic predisposition. Various factors, such as sleep deprivation, certain medications, alcohol consumption, stress, and underlying medical conditions, can trigger sleepwalking episodes.

While sleepwalking episodes typically last a few seconds to a few minutes, they can occasionally extend beyond 30 minutes. Sleepwalkers may sit up and appear awake, get up and walk around, or perform complex activities such as moving furniture or driving a car. They may exhibit a blank look on their face, open their eyes during sleep, and display aggressive behaviour if awakened.

In contrast, RBD episodes typically occur at least 90 minutes after falling asleep, during the REM stage of sleep. During RBD episodes, individuals may talk, shout, scream, kick, punch, or jump out of bed. These episodes can be dangerous, leading to accidental injuries to oneself or one's bed partner.

While sleepwalking is usually more challenging to wake up from than RBD episodes, it is not dangerous to awaken a sleepwalker. They may be confused or disoriented for a short time upon waking but will eventually regain their bearings.

In summary, while sleepwalking and REM sleep are distinct conditions, they share some similarities in the types of movements exhibited and the potential risks involved. Sleepwalking occurs during deep, non-REM sleep and is influenced by genetic and environmental factors. On the other hand, RBD occurs during REM sleep and involves acting out vivid dreams, with individuals typically recalling their dreams upon waking. Both conditions can result in complex movements and pose risks of injury, highlighting the importance of creating a safe sleep environment.

Frequently asked questions