Rem Sleep: A Dangerous Mystery Unveiled

REM sleep, or rapid eye movement sleep, is the fourth of four stages of sleep. It is characterised by relaxed muscles, quick eye movement, irregular breathing, an elevated heart rate, and increased brain activity. While it is important for learning and memory, REM sleep has also been linked to several sleep disorders, including REM sleep behaviour disorder (RBD), where sleepers act out their dreams, and nightmare disorder.

REM sleep behaviour disorder (RBD)

During normal REM sleep, the body temporarily paralyses most of the skeletal muscles, allowing people to dream safely. However, for those with RBD, this temporary paralysis does not occur, and they can unknowingly act out their dreams. The exact cause of this is unknown, but researchers believe it may be due to a breakdown in the area of the brainstem responsible for regulating REM sleep.

RBD can be divided into two main types: isolated (idiopathic) and symptomatic (secondary). Isolated RBD occurs without an underlying cause, and most people with this type will eventually develop a neurodegenerative condition, such as Parkinson's disease, Lewy body dementia, or multiple system atrophy (MSA). Symptomatic RBD is caused by an underlying condition, such as Type 1 narcolepsy, or the use of certain medications, such as antidepressants.

The symptoms of RBD can vary in severity, ranging from mild muscle twitches to more violent behaviours such as kicking, punching, or screaming. About 80% of people with RBD experience sleep-related injuries, and it can also cause frequent sleep disruptions, affecting overall sleep quality. RBD is most common in people over 50, with an average age of onset at 61 years. It is nine times more common in men than in women.

Treatment for RBD focuses on creating a safe sleeping environment and may include safety measures such as removing sharp objects from the bedroom and placing pillows or barriers around the bed. Medications such as melatonin, clonazepam, and pramipexole may also be prescribed to help manage symptoms.

Lack of REM sleep symptoms

A lack of REM sleep can have a detrimental impact on your health and well-being. Here are some of the symptoms that may indicate you are not getting enough REM sleep:

• Fatigue and drowsiness: A clear sign of sleep deprivation is feeling tired and sleepy during the day. This can affect your ability to carry out daily tasks and can even be dangerous if you are driving or operating machinery.
• Cognitive issues: Lack of REM sleep can lead to problems with concentration, memory, and problem-solving. You may find it difficult to focus and retain information.
• Mood changes: REM sleep plays a role in emotional processing. A lack of REM sleep can result in irritability, anxiety, and mood swings.
• Poor decision-making: Being sleep-deprived can lead to careless actions and poor decisions, which can be dangerous and impact your overall well-being.
• Increased health risks: Research suggests that insufficient REM sleep is linked to a higher risk of cardiovascular disease, type 2 diabetes, cancer, stroke, and neurodegenerative diseases like Alzheimer's.
• Weight gain and increased appetite: Lack of REM sleep can disrupt the hormones that regulate appetite, leading to weight gain and a higher risk of obesity.
• Weakened immune system: Sleep is crucial for the body's immune system to function effectively. Not getting enough REM sleep can make you more susceptible to illnesses.
• Microsleep: Sleep deprivation may lead to brief moments of unintentional sleep, known as microsleep. These episodes can occur during the day and can be dangerous if they happen while driving or performing other tasks that require concentration.
• Forgetfulness: REM sleep is important for memory consolidation. A lack of REM sleep can result in forgetfulness and difficulties with memory recall.
• Impaired learning: REM sleep is believed to play a crucial role in learning and critical thinking. Not getting enough REM sleep can impact your ability to acquire and consolidate new information.

Benefits of REM sleep

REM sleep is the fourth and final stage of the sleep cycle. During this stage, the body is immobilised, but the brain remains active, resulting in rapid eye movements. The first REM stage of sleep lasts for about 10 minutes, but the duration increases as the sleep cycle repeats throughout the night. While the amount of REM sleep we get decreases as we age, it is crucial for our overall health and immune system. Here are some of the benefits of REM sleep:

Memory Consolidation and Learning

REM sleep plays a vital role in memory consolidation and learning. During this stage, the brain processes new information and experiences, committing some to memory and deciding which ones to delete. Research has shown that sleep deprivation can negatively impact working memory and increase the risk of forming false memories.

Emotional Processing

REM sleep is associated with emotional processing and mood regulation. The amygdala, the part of the brain responsible for processing emotions, is activated during this stage. Studies suggest that people who get sufficient REM sleep are better able to judge facial expressions and are less likely to have strong reactions to emotional images.

Brain Development

REM sleep is particularly important for brain development in infants and children. Newborns spend a significant amount of their sleep time in REM, and the number of minutes of REM sleep decreases as people age. Research indicates that REM sleep provides the neural stimulation necessary for mature brain structure development.

Dreaming

The majority of dreams occur during REM sleep, and they are typically more vivid than dreams during non-REM sleep. While the exact function of dreams is still debated, some theories suggest that they may aid in emotional processing, memory consolidation, or preparing for challenging situations.

Cell Repair and Regeneration

The last stage of non-REM sleep, along with REM sleep, is involved in repairing and regenerating the body's cells. This process helps in treating various health disorders and maintaining overall health.

Bone Health and Muscle Growth

Quality REM sleep is crucial for bone health and muscle growth, regardless of age. It also influences how nerve cells (neurons) communicate with each other, contributing to overall brain function.

Boosted Immune System

REM sleep boosts the immune system by triggering hormone production, which helps maintain a healthy body temperature.

In summary, REM sleep is essential for various aspects of our health, including memory, emotional processing, brain development, dreaming, cell repair, bone and muscle health, and immune function.

REM rebound

Factors that can cause REM rebound and an increase in REM sleep percentage include REM sleep deprivation, withdrawal from REM-suppressing medications (such as selective serotonin reuptake inhibitors), substance withdrawal (e.g. alcohol or cocaine), depression, and CPAP titration.

REM sleep plays an important role in brain maturation, maintaining minimal brain activity during sleep, memory consolidation, supporting brain neurotransmitter systems, and regulating emotions. Thus, REM rebound following stress serves as an important adaptive function.

REM sleep cycles

REM sleep, or rapid eye movement sleep, is the fourth stage of sleep. It is characterised by relaxed muscles, quick eye movement, irregular breathing, an elevated heart rate, and increased brain activity.

During a full night's sleep, we 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.

The first REM cycle begins about 60 to 90 minutes after falling asleep and lasts about 10 minutes. The first cycle of REM sleep is typically the shortest, and each cycle that follows gets longer and longer, up to an hour. The final REM cycle may last up to an hour.

During REM sleep, your eyes move rapidly behind your closed eyelids, your heart rate speeds up, and your breathing becomes irregular. Your brain is highly active during REM sleep, and your brain waves become more variable. Your body operates similarly to how it does when you are awake, except your eyes are closed and your muscles experience temporary loss of tone. This temporary paralysis may be a protective measure to stop you from acting out your dreams and injuring yourself.

REM sleep plays an important role in several functions, including:

• Dreaming: Most of your dreams occur during REM sleep and are usually more vivid than non-REM dreams.
• Memory Consolidation: Your brain processes new learnings and motor skills from the day, committing some to memory and deciding which ones to delete.
• Emotional Processing: Your brain processes emotions during REM sleep, and your amygdala, which is responsible for processing emotions, activates during this stage.
• Brain Development: Researchers hypothesise that REM sleep promotes brain development, as newborns spend most of their sleep time in this stage.

While REM sleep is not inherently dangerous, a sleep disorder called REM Sleep Behaviour Disorder (RBD) can cause those affected to act out their dreams, potentially injuring themselves or their bed partner. This occurs due to a breakdown in the area of the brainstem responsible for regulating REM sleep, resulting in a loss of temporary paralysis during this sleep stage.

Frequently asked questions