Dream Pain: Can We Feel It During Rem Sleep?

Sleep and pain are closely linked and impact each other. People with chronic pain often find it difficult to fall asleep, and their sleep is disrupted by long night awakenings. This bidirectional relationship means that pain during the day affects sleep quality, and poor sleep increases pain levels the next day. In fact, recent findings suggest that sleep may affect pain levels more than the other way around. During the REM stage of sleep, the body repairs and regrows tissues, builds bone and muscle, and strengthens the immune system.

Dreaming and memory consolidation

Memory consolidation is a time-dependent stabilisation process that eventually leads to the permanent storage of newly acquired memory. It involves the integration of multiple experiences and the extraction of generalities. During dreaming, the intermingling of memory fragments into novel and sometimes bizarre combinations could reflect this adaptive process.

The relationship between dreaming and memory consolidation is supported by the following:

• Dreaming is associated with the reactivation of waking life.
• Dreaming could induce memory reconsolidation.
• Dreaming is the result of cholinergic and aminergic transmitters, and both of these systems participate together in consolidation and reconsolidation.
• Dreaming is characterised by high visuality, vividity, and clarity.
• Dreaming is an ideal context for memory reconsolidation.
• Dreaming is the result of the hyperactivity of the limbic and paralimbic structures, including amygdaloid complexes, hippocampal, and anterior cingulate cortex (ACC).

Emotional processing

The amygdala, the part of the brain responsible for processing emotions, is activated during REM sleep. This activation helps in the consolidation of emotional memories, which can aid in improving learning and problem-solving abilities.

The emotional processing that occurs during REM sleep is crucial for maintaining healthy brain development and function. It is believed to aid in the development of the central nervous system, which includes the brain and spinal cord. This may explain why newborns spend a significant portion of their sleep in the REM stage.

Additionally, the amount of REM sleep an individual needs varies with age. Newborns spend about half of their sleep in REM, which gradually decreases to around 20% by the age of 20. As people age further, the time spent in REM sleep decreases slightly, reaching about 17% by the age of 80.

The regulation of emotions during REM sleep can also impact an individual's ability to cope with emotions when they are awake. A lack of REM sleep can lead to symptoms such as trouble coping with emotions and difficulty concentrating.

Overall, REM sleep plays a vital role in emotional processing, memory consolidation, brain development, and dreaming.

Brain development

REM sleep is important for brain development, particularly in newborns and infants. During this stage of sleep, the brain prunes its synapses, improving memory and problem-solving abilities. It also processes emotional memories, including those associated with fear, and is thought to aid in the development of the central nervous system, which includes the brain and spinal cord.

REM sleep is characterised by relaxed muscles, quick eye movement, irregular breathing, elevated heart rate, and increased brain activity. It is the fourth of four stages of sleep, coming after three stages of non-REM sleep. During non-REM sleep, the brain is less active, and the body repairs and regrows tissues, builds bone and muscle, and strengthens the immune system.

The amount of REM sleep needed varies with age. Newborns spend about half their sleep time in REM sleep, which decreases to just over 20% by age 20. In older adults, time spent in REM sleep decreases slightly to about 17% by age 80.

REM sleep is also important for dreaming, memory, and emotional processing. Most dreams occur during this stage of sleep, and the increased brain activity during REM sleep is similar to brain activity when awake.

Pain and sleep are closely linked and impact each other

Chronic pain can affect sleep in different ways and depends on the nature of the pain. Some conditions may flare up at night or be provoked by certain sleeping positions. Others may cause persistent pain that does not ease at night. A noisy environment or an uncomfortable bed may also be additional challenges.

Chronic pain can also cause frequent nighttime wakings, which is the most common sleep complaint in people with chronic pain. As we sleep, we cycle through light sleep, slow-wave sleep, and rapid eye movement (REM) sleep. In order to feel well-rested, we need a balance of all these sleep stages, especially slow-wave sleep and REM sleep. Disrupting this cycle leads to less restful sleep and next-day tiredness.

Apart from the pain itself, some people with chronic pain also experience one or more sleep disorders such as obstructive sleep apnea or restless legs syndrome. Medication for pain or for a chronic illness may carry side effects that interfere with sleep. Pain can also be accompanied by anxiety, stress, or depression, which can cause sleep problems.

There is an unquestionable link between sleep and pain, and emerging evidence suggests that the effect of sleep on pain may be even stronger than the effect of pain on sleep. Researchers have found that short sleep times, fragmented sleep, and poor sleep quality often cause heightened sensitivity to pain the following day in chronic conditions. People with sleep problems also appear to be at a higher risk of eventually developing conditions like fibromyalgia and migraines. Encouragingly, many studies have also found that, in the long term, quality sleep may improve chronic pain.

Sleep and pain appear to share similar pathways and neurotransmitters. For example, melatonin is best known for its role in regulating our circadian rhythm, and new research is starting to uncover its role in our perception of pain. Sleep loss also causes inflammation in the immune system, with corresponding effects on our body's resilience. Vitamin D and dopamine also appear to play a role in both sleep and pain.

Sleep deprivation and its effects

Sleep is a basic human need, as important as eating, drinking, and breathing. Sleep deprivation can have far-reaching effects on your health, well-being, and safety. It can affect your mood, memory, and judgement, and increase your risk of developing serious health conditions.

• Central nervous system: Sleep is necessary to keep your central nervous system functioning properly. Sleep deprivation can disrupt how your body sends and processes information, affecting your concentration, learning, and coordination. It can also lead to mood swings, impaired decision-making, and even hallucinations.
• Immune system: Sleep deprivation weakens your immune system, reducing the production of protective substances like antibodies and cytokines, making you more susceptible to illnesses like the common cold and flu. It also increases your risk of developing chronic conditions such as diabetes and heart disease.
• Weight gain and obesity: Sleep affects the hormones that control hunger and fullness, leading to increased appetite and nighttime snacking. It can also make you too tired to exercise, resulting in reduced physical activity and weight gain.
• Cardiovascular system: Sleep is vital for maintaining a healthy heart and blood vessels. Sleep deprivation is linked to an increased risk of cardiovascular disease, heart attack, and stroke.
• Hormone production: Sleep disruption can affect the production of important hormones, including testosterone and growth hormones, which are crucial for muscle growth, cell repair, and other bodily functions.
• Mental health: Sleep deprivation can negatively impact your mental health, causing irritability, mood swings, and increased stress levels. It can also compromise creativity and decision-making abilities.
• Safety: Sleep-deprived individuals are at a higher risk of accidents, especially when driving or operating heavy machinery. It is estimated that drowsy driving causes 6,000 fatal car crashes each year in the United States.
• Increased risk of cancer: Sleep deprivation has been linked to an increased risk of certain cancers, including colorectal cancer.
• Dementia: Lack of sleep can increase the risk of developing dementia. Research suggests that for every 1% reduction in REM sleep, there is a corresponding 9% increase in dementia risk.
• Ageing: Sleep deprivation can accelerate brain ageing, with studies showing that it can make your brain appear 3-5 years older than it actually is.

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