The Importance Of Rem Sleep For Survival

Sleep is not considered a pathological state, but it does consume a third of our conscious lives. While we know that sleep is necessary for long-term survival, it is unclear whether we can survive without REM sleep specifically. REM sleep is characterised by heightened brain activity and is the state in which dreams are most intense. It is thought to be important for learning and memory, and it helps us concentrate and regulate our mood. However, there are cases of people who have survived without it. For example, a man in Israel with no REM sleep went to law school and became a puzzle editor for a newspaper.

REM sleep is also thought to be linked to a higher risk of death. A study published in JAMA Neurology found that men who experienced a 5% loss of REM sleep had a 13% higher death rate from cardiovascular disease and other causes. However, the study did not include a racially diverse sample, and it may not have fully controlled for depression, as many participants were taking antidepressants, which are known to affect REM sleep.

While it is difficult to say whether we can survive without REM sleep, it is clear that sleep deprivation has serious consequences for our health and well-being.

REM sleep and memory consolidation

REM sleep is a stage of sleep in which we dream and information and experiences are consolidated and stored in memory. It is thought to be important for daytime function and wakefulness, and may help with learning and memory consolidation.

REM sleep is characterised by brain activity, rapid eye movement, muscle paralysis, and dreaming. It occurs in four to six short cycles, beginning about 90 minutes after falling asleep and often increasing towards the end of sleep time.

A lack of REM sleep can lead to fatigue, irritability, changes in mood and memory, and issues with cognition and problem-solving. It can also contribute to health issues such as cardiovascular disease, type 2 diabetes, cancer, stroke, and neurodegenerative diseases like Alzheimer's.

To increase REM sleep, try to keep a regular sleep schedule, exercise, limit the use of electronic devices before bedtime, and avoid heavy meals before bed.

REM sleep deprivation and mortality risk

REM sleep is a stage of sleep characterised by rapid eye movement, dreaming, and the consolidation and storage of information and experiences in memory. While the purpose of REM sleep is still unknown, it is thought to be important for daytime function and wakefulness, and may help with learning and memory.

A 2020 study published in JAMA Neurology found that spending less time in REM sleep is linked to a greater overall risk of death from any cause, as well as from cardiovascular disease and other diseases except for cancer. The study analysed the sleep patterns of 2,675 men who participated in the clinical trial "Outcomes of Sleep Disorders in Older Men" (MrOS), and 1,375 men and women who were part of the Wisconsin Sleep Cohort. The results showed that men in the MrOS study had a 13% higher cardiovascular and overall death rate over a dozen years for every 5% loss of REM sleep, even after adjusting for multiple demographic, sleep and health variables. These findings were mirrored in the Wisconsin study, which followed participants for over 20 years and included women.

It is important to note that the study did not include a representative sample of African Americans and other races, and may not have fully controlled for depression, as many of the participants were on antidepressants, which are known to affect REM sleep. As such, further studies are needed to confirm these findings and exclude the possible contribution of depression.

While the exact mechanisms are not yet fully understood, several theories exist regarding the function of REM sleep and its potential impact on mortality risk. One theory suggests that REM sleep helps in forming new memories, while another proposes that it stimulates the central nervous system. Additionally, REM sleep may also play a role in restoring brain chemistry to a normal balance. Previous studies have shown that a short REM duration may lead to memory deficits and poor cognitive outcomes, while sleep apnea occurring during REM sleep has been linked to high blood pressure and deaths from cardiovascular disease.

Overall, while the link between REM sleep deprivation and mortality risk requires further investigation, the current evidence suggests that adequate REM sleep is crucial for maintaining optimal health and well-being.

REM sleep and antidepressants

Antidepressants are known to affect REM sleep quality and quantity. Most antidepressants suppress REM sleep, which is thought to be important for brain function. However, the resulting REM sleep restriction is well tolerated. Antidepressants that increase serotonin function by blocking reuptake or by inhibiting metabolism have the greatest effect on REM sleep.

Selective serotonin reuptake inhibitors (SSRIs) and tricyclic antidepressants (TCAs) have different effects on REM sleep. SSRIs do not activate the REM sleep homeostat, while TCAs elicit a homeostatic response similar to that of REM sleep restriction. Despite the differences, the REM sleep homeostat remains active even in the presence of pharmacological REM sleep inhibition antidepressants.

In healthy volunteers and depressed patients, reductions in the amount of REM sleep and increases in REM sleep onset latency are seen after taking antidepressants. These changes in REM sleep patterns tend to be in the opposite direction to the sleep abnormalities found in major depression but are usually of a greater degree.

The effects of antidepressants on sleep initiation and maintenance are less consistent between drugs. Some antidepressants, like clomipramine and SSRIs, are sleep-disturbing early in treatment, while others, like amitriptyline and serotonin 5-HT2-receptor antagonists, are sleep-promoting. However, these effects are short-lived, and there are minimal differences between drugs after a few weeks of treatment.

The impact of antidepressants on REM sleep may have implications for patients' quality of life. Antidepressant use has been associated with increased REM sleep latency and a complete lack of REM sleep, which may contribute to poorer quality-of-life scores. This could be due to issues such as daytime sleepiness.

REM sleep and brain development

REM sleep is vital for brain development, particularly in newborns. It is characterised by desynchronised cortical activity with low-voltage and high-frequency electroencephalograms (EEGs). During this sleep stage, the brain is active, and the body is temporarily paralysed, except for the muscles used for eye movement and breathing.

REM sleep is thought to play a role in the development of the central nervous system, maintaining and establishing new connections, particularly during early brain development. It is also believed to be important for procedural memory, which is the type of memory used when learning a new skill.

Recent findings have shown that REM sleep selectively prunes newly formed dendritic spines in the developing brain, strengthening new synapses. This process is critical for normal neuronal circuit development and behavioural improvement after learning.

During early brain development, REM sleep provides the neural stimulation needed to develop and prepare the neural circuitry for later higher cognitive processing. REM sleep facilitates the formation of new spines in the motor cortex during development and strengthens the synapses necessary for performance improvement after learning a new motor skill.

The importance of REM sleep for brain development is further emphasised by behavioural studies, which have shown a correlation between decreased startles and twitches in human neonates and poor behavioural and neurological outcomes at a later age. This suggests that twitches influence not only motor development but also the neural circuitry involved in sensory processing.

Overall, REM sleep is crucial for brain development, particularly in newborns, as it contributes to the formation and maintenance of synapses and the development of the central nervous system.

REM sleep and mental health

REM sleep, or rapid eye movement sleep, is a stage of sleep that is characterised by vivid dreams, increased brain activity, and muscle paralysis. While the exact purpose of REM sleep is unknown, it is thought to be important for memory consolidation and daytime function.

The Link Between REM Sleep and Mental Health

Research suggests that a lack of REM sleep can negatively impact mental health and cognitive function. Depressed or anxious individuals who were awakened during REM sleep reported more negative self-appraisals and recalled negative memories more frequently. They also rated themselves significantly less positively compared to others, and their dreams were associated with greater frequencies of negative emotion, aggression, and victimisation.

Furthermore, disruptions to REM sleep have been linked to certain types of depression. Some studies have found that both selective REM sleep deprivation and total sleep deprivation can provide temporary relief from depressive symptoms, suggesting that REM sleep may play a role in producing clinical symptoms in some individuals with mood disorders.

Additionally, REM sleep behaviour disorder (RBD) is a parasomnia in which individuals physically act out their dreams during the REM stage of sleep. RBD is strongly associated with certain neurodegenerative disorders, such as Parkinson's disease and Lewy body dementia. While RBD can be caused by certain antidepressants, it is often a precursor to the development of these neurological conditions.

The Impact of Sleep Deprivation

Sleep deprivation, including a lack of REM sleep, has been linked to various health issues, including obesity, metabolic disorders, and cardiovascular problems. It can also contribute to a higher risk of accidents, errors, and reduced quality of life. Chronic sleep loss is considered a public health epidemic, affecting up to 45% of the global population.

In summary, REM sleep plays a crucial role in maintaining mental health and overall well-being. Disruptions to REM sleep can have negative consequences for cognitive function and mood, while long-term sleep deprivation can lead to physical health issues and impact society as a whole.

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