Gina Johnson
Rapid eye movement (REM) sleep is a unique phase of sleep in humans and other mammals, during which the eyes move rapidly, and the body experiences low muscle tone and a propensity to dream vividly. It is characterised by increased brain activity, with brain waves resembling the pattern seen during wakefulness. The first cycle of REM sleep typically occurs around 60 to 90 minutes after falling asleep, with each cycle increasing in duration throughout the night.
REM sleep is important for several reasons. Firstly, it plays a role in memory consolidation, with studies showing that sleep deprivation can negatively impact memory formation. Secondly, it aids in emotional processing as the amygdala, the part of the brain responsible for processing emotions, is active during this stage. Thirdly, REM sleep is crucial for brain development, especially in infants, who spend a large proportion of their sleep in this stage. Finally, REM sleep is associated with dreaming, with most dreams occurring during this stage due to the high brain activity.
| Characteristics | Values |
|---|---|
| Name | Rapid Eye Movement (REM) Sleep |
| Number of Stages | 4 |
| Eye Movement | Rapid |
| Muscle Tone | Relaxed |
| Breathing | Quick and Irregular |
| Heart Rate | Elevated |
| Brain Activity | Increased |
| Occurrence | Every 90 minutes |
What You'll Learn
REM sleep is associated with dreaming and memory consolidation
Memory consolidation is the process of "strengthening" memory traces into more permanent forms of long-term storage. 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. This is done by the reactivation of memory traces, which are then consolidated into long-term storage.
The brain regions activated during REM sleep are approximately inverse to those activated during non-REM sleep and display greater activity than in quiet waking. The superior frontal gyrus, medial frontal areas, intraparietal sulcus, and superior parietal cortex, areas involved in sophisticated mental activity, show equal activity in REM sleep as in wakefulness.
REM sleep is also associated with emotional processing, as the amygdala, the part of the brain that processes emotions, is activated during this stage.
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During REM sleep, the body experiences temporary paralysis
REM atonia serves as a protective mechanism to prevent people from acting out their dreams and causing potential injury. However, this hypothesis has been challenged by the discovery that dreams can also occur during non-REM sleep stages when the body is not paralysed.
The transition to REM sleep brings about marked physical changes, including electrical bursts known as ponto-geniculo-occipital waves, which originate in the brain stem. The body abruptly loses muscle tone, and other muscles may twitch under the influence of these waves.
REM sleep typically occurs about 60 to 90 minutes after falling asleep, and each cycle through all sleep stages takes around 90 to 120 minutes to complete. As the night progresses, the amount of time spent in REM sleep increases, with most of it occurring in the second half of the night.
While the exact function of REM sleep remains unclear, several theories have been proposed. One theory suggests that it aids in memory consolidation, with the brain processing and committing new learnings and motor skills to memory. Another theory proposes that REM sleep promotes brain development, especially in newborns who spend a significant portion of their sleep in this stage.
REM sleep is also associated with emotional processing, as dreams may play a role in this process, and the amygdala, responsible for processing emotions, is activated during this stage. Additionally, the "sentinel hypothesis" suggests that REM sleep periodically activates animals to scan their environment for potential threats.
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The brain is highly active during REM sleep
During REM sleep, the brain is highly active. Brain activity during REM sleep looks similar to brain activity when awake. Brain energy use in REM sleep, as measured by oxygen and glucose metabolism, equals or exceeds energy use when awake. The rate in non-REM sleep is 11-40% lower.
REM sleep is characterised by relaxed muscles, quick eye movement, irregular breathing, elevated heart rate, and increased brain activity. During this stage, the brain processes emotions and consolidates memory. Dreaming also mostly occurs during REM sleep.
The brainstem plays a special role in REM sleep. It sends signals to relax muscles essential for body posture and limb movements, so that we don't act out our dreams. However, this hypothesis is losing steam now that scientists know we can experience dreams during non-REM sleep stages when our bodies are not paralysed.
The amygdala, an almond-shaped structure involved in processing emotions, becomes increasingly active during REM sleep.
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REM sleep is important for brain development in infants
Rapid Eye Movement (REM) sleep is the fourth of four stages of sleep. It is characterised by relaxed muscles, quick eye movement, irregular breathing, elevated heart rate, and increased brain activity.
REM sleep is important for brain development, especially in infants. Infants born at term average 16 to 18 hours of sleep per day, with 50% of it in REM sleep. Premature infants spend even more time asleep; up to 80% of it in REM sleep. The greater time spent in REM sleep in infancy and early childhood is thought to reflect the crucial role REM sleep plays in fostering optimal brain development, cognition, and behaviour.
REM sleep is associated with dreaming and memory consolidation. It was first discovered in the 1950s when scientists studying sleeping infants noticed distinct periods when their eyes moved rapidly from side to side.
During REM sleep, the brain is highly active, and brain waves become more variable. The brain processes new learnings and motor skills from the day, committing some to memory, maintaining others, and deciding which ones to delete.
Researchers hypothesise that REM sleep promotes brain development, as newborns spend most of their sleep time in this stage. Further evidence for this comes from the fact that animals born with less developed brains, such as humans and puppies, spend even more time in REM sleep during infancy than those born with more developed brains, like horses and birds.
REM sleep is also important for wakefulness preparation. Through its activation of the central nervous system, it might help us prepare to wake up. This may explain why we spend increasing amounts of time in REM sleep as the night progresses and why we are easier to wake up during this stage.
In summary, REM sleep is crucial for brain development in infants, with newborns spending up to eight hours in REM sleep each day. It plays a key role in dreaming, memory consolidation, emotional processing, and healthy brain development.
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A lack of REM sleep may negatively impact physical and mental health
A lack of REM sleep can have detrimental effects on both physical and mental health.
REM sleep is one of the two major natural sleep stages and is characterised by relaxed muscles, quick eye movement, irregular breathing, elevated heart rate, and increased brain activity. During this stage, the brain consolidates memories and processes emotions.
Missing out on REM sleep can lead to sleep deprivation, which can cause difficulty concentrating during the day, excessive daytime sleepiness, and forgetfulness or poor memory. Over time, chronic sleep deprivation can lead to more severe health conditions, such as diabetes, depression, obesity, and cardiovascular disease.
A lack of REM sleep can also negatively impact physical health. It can affect cardiovascular health and increase the risk of type 2 diabetes. Research has also found links between a lack of REM sleep and cancer, stroke, and neurodegenerative diseases like Alzheimer's.
Furthermore, disruptions in REM sleep have been associated with an increased risk of obesity and migraines. Studies have shown that even short periods of REM sleep deprivation can increase the risk of forming false memories.
In summary, getting adequate REM sleep is crucial for maintaining optimal physical and mental health.
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Frequently asked questions
REM stands for rapid eye movement sleep. It is the fourth of four stages of sleep and is characterised by relaxed muscles, quick eye movement, irregular breathing, elevated heart rate, and increased brain activity.
In non-REM sleep, the eyes don't move, brain waves are slower, and the body maintains some muscle tone. In contrast, during REM sleep, brain wave activity is similar to wakefulness, there is a complete loss of muscle tone, breathing is irregular, and the heart rate rises.
Most adults need about two hours of REM sleep each night.
Multiple studies suggest that REM sleep deprivation can interfere with memory formation. However, this could also be due to overall sleep disruption, as the two often occur together.
REM sleep behaviour disorder (RBD) is a parasomnia where the muscle paralysis that usually occurs during REM sleep is absent, leading to people acting out their dreams. It is often associated with antidepressant use and neurodegenerative conditions.
