The Importance Of Rem Sleep And How Much We Need

Sleep plays a crucial role in our health and well-being, and the quality of sleep we get is just as important as the quantity. Sleep occurs in different stages, including REM sleep, which stands for rapid eye movement sleep. During REM sleep, the eyes move rapidly, the body becomes temporarily paralysed, and the brain is highly active, with brain activity resembling that of a waking person. Dreams typically occur during this stage of sleep, and it is believed to be important for learning, memory, and emotional processing. While there is no official agreement on how much REM sleep is needed, it is estimated that REM sleep makes up about 20-25% of the total sleep cycle for adults, which equates to around two hours for those sleeping for seven to eight hours per night.

How Much REM Sleep?

REM sleep and dreaming

Sleep is divided into four stages, three of which are non-rapid eye movement (NREM) sleep, and the fourth is rapid eye movement (REM) sleep. After falling asleep, the body goes through non-REM sleep first, followed by a shorter period of REM sleep, and then the cycle starts over again. Each cycle lasts between 90 and 120 minutes.

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 its activity when a person is awake. Dreams typically occur during REM sleep, and they tend to be more vivid than dreams during non-REM sleep. The body also temporarily paralyses during REM sleep to prevent the sleeper from acting out their dreams.

REM sleep is important for several reasons. Firstly, it is associated with dreaming, which experts believe helps individuals process their emotions. Secondly, it stimulates areas of the brain that aid in learning and memory. During this stage, the brain repairs itself, processes emotional experiences, and transfers short-term memories into long-term memories. Finally, REM sleep may also play a role in brain development, especially in infants and children.

The amount of REM sleep needed varies depending on age. Newborn babies spend up to eight hours in REM sleep each day, while adults only need an average of two hours per night. Overall, adults should aim for 7-9 hours of sleep per night, with about 20-25% of that time spent in the REM stage.

REM sleep and memory consolidation

REM sleep is vital for memory consolidation, learning, and creativity. During REM sleep, the brain is active, and dreams typically occur. It stimulates the areas of the brain that help with learning and memory, and the brain repairs itself and processes emotional experiences. REM sleep is believed to be essential to cognitive functions such as memory, learning, and creativity.

REM sleep is one of the two types of sleep, the other being non-REM sleep. A person cycles through these stages 4-5 times every night. The first REM stage is short, but as sleep progresses, it gets longer compared to non-REM sleep. The first REM cycle usually begins about 90 minutes after falling asleep and recurs every 90 minutes. Each cycle includes three stages of non-REM sleep and a stage of REM sleep.

During non-REM sleep, the brain is not as active, and in the deeper stages of non-REM sleep, the body repairs and regrows tissues, builds bone and muscle, and strengthens the immune system. In adults, stage 3 of non-REM sleep makes up about 25% of total sleep time.

While the amount of REM sleep a person needs is not officially agreed upon, it usually makes up about 20-25% of total sleep time for adults.

REM sleep and emotional processing

REM sleep is believed to be essential to our ability to cope with emotional stress in everyday life. It is thought to be important for regulating our emotional brain-state and plays a key role in regulating emotion. REM sleep is when we tend to dream, and experts believe dreaming helps us process emotions.

REM sleep deprivation studies have found that negative emotional reactivity is enhanced and positive reactions to positive events are often subdued. REM sleep deprivation has been found to increase negative affect and impair the ability to regulate emotions.

REM sleep is associated with increased activity in emotion-related areas, including the amygdala, striatum, hippocampus, and medial prefrontal cortex.

REM sleep may be adaptive to process aversive experiences such as traumatic experiences, by presenting them as strange images and fragmented episodes of related or similar stories.

REM sleep deprivation is both a common symptom of and risk factor for a range of psychiatric disorders including anxiety and mood disorders.

REM sleep suppression increases general negative affect and enhances amygdala responses and alters its functional connectivity with anterior cingulate cortex during passively experienced experimental social exclusion.

REM sleep suppression did not impact the ability to apply cognitive reappraisal, neither behaviorally nor neurally.

REM sleep suppression did not have a significant impact on emotions after social exclusion.

REM sleep and brain development

Sleep plays a critical role in brain development, with REM sleep and non-REM sleep contributing differently to the process. REM sleep, or "dream sleep", is characterised by desynchronised cortical activity and is associated with dreaming. During this stage, the brain is active, and people may experience intense dreams as their eyes move rapidly. REM sleep is vital for brain development as it strengthens new synapses and selectively prunes newly formed dendritic spines in the developing brain. This process is essential for normal neuronal circuit development and behavioural improvement. Studies have shown that REM sleep deprivation in early development can delay maturation of the visual cortex and motor system in rats. Furthermore, REM sleep is linked to the development of cognitive functions such as memory, learning, and creativity.

On the other hand, non-REM sleep is a period of restful and restorative sleep. It is divided into three stages, with the third stage being the deepest sleep stage. During this stage, the body repairs and regenerates tissues, builds bone and muscle, and strengthens the immune system. While non-REM sleep contributes to physical restoration, it also plays a role in brain development by optimising neuronal networks through synaptic downscaling and pruning. The slow-wave activity that occurs during non-REM sleep influences brain maturation, with studies showing that it is associated with synaptic pruning.

The balance between REM and non-REM sleep changes as individuals age. Newborns have more REM sleep, which gradually decreases throughout childhood and adulthood. The proportion of deep sleep, a part of non-REM sleep, peaks in early childhood and then declines over time. Therefore, sufficient and good-quality sleep is crucial for brain development, especially in the early years of life.

REM sleep and the impact of sleep disorders

Sleep is essential for health and well-being. A good night's rest involves spending adequate time in each of the sleep stages, including REM sleep. REM stands for rapid eye movement and is characterised by vivid dreams, rapid eye movements, and active brain activity. While the amount of REM sleep needed is not definitively agreed upon, it is estimated that REM sleep accounts for about 20-25% of total sleep time in healthy adults.

REM sleep behaviour disorder (RBD) is a parasomnia in which individuals physically and/or vocally act out their dreams during the REM stage. The disorder can cause individuals to engage in complex movements and even violent behaviour, potentially resulting in injuries to themselves or their bed partners. RBD is relatively rare, affecting approximately 1% of the general US population and 2% of those aged 50 or older. However, the true rates may be higher due to the challenges associated with diagnosing this disorder.

The symptoms of RBD can vary in severity and typically occur at least 90 minutes after falling asleep. Individuals with RBD may experience mild muscle twitches, shout or scream, kick or punch, or even jump out of bed. About 80% of people with RBD experience sleep-related injuries, and their bed partners are also at risk. The disorder can be particularly dangerous, and safety measures such as removing sharp objects from the bedroom and creating a safe sleeping environment are crucial.

RBD is strongly associated with certain neurodegenerative disorders, particularly Parkinson's disease, Lewy body dementia, and multiple system atrophy. It is also linked to narcolepsy and the use of certain antidepressants. While there is no definitive cure for RBD, treatment options include medication such as clonazepam and melatonin, as well as implementing safety precautions to prevent injuries.

In summary, REM sleep is a crucial aspect of the sleep cycle, and disruptions to this stage of sleep, such as those caused by RBD, can have significant impacts on individuals' health, safety, and overall well-being.

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