Dreaming And Rem Sleep: Understanding The Connection

Sleep is a complex and mysterious process that has been the subject of extensive research by experts in the fields of neuroscience and psychology. While the specific reasons for why we dream remain unknown, dreams are typically associated with the rapid eye movement (REM) stage of sleep, characterised by relaxed muscles, quick eye movement, irregular breathing, elevated heart rate, and increased brain activity. REM sleep is believed to play a crucial role in memory consolidation, emotional processing, brain development, and dreaming itself.

Dreaming occurs in non-REM sleep too

Dreams are fascinating and mysterious aspects of sleep. Dreaming is considered healthy and normal, but frequent nightmares can interfere with sleep. While everyone dreams, the content of those dreams and their effect on sleep can vary dramatically from person to person.

The most common and intense dreams occur during REM sleep when brain activity increases. However, dreaming can also happen during non-REM sleep.

REM sleep

REM sleep is the fourth out of four total stages of sleep. It is characterised by relaxed muscles, quick eye movement, irregular breathing, elevated heart rate, and increased brain activity. Most adults need about two hours of REM sleep each night.

REM sleep is important for:

• Dreaming
• Memory consolidation
• Emotional processing
• Brain development
• Wakefulness preparation

Non-REM sleep

Non-REM sleep has three stages:

• Light sleep: Your brain slows down, and your body has some muscle tone and regular breathing.
• Light sleep: Your heart rate and body temperature decrease, and specific brain wave patterns begin to occur as you transition toward deep sleep.
• Deep sleep: Your brain waves are at their slowest, and it's difficult to wake you up. Your body repairs itself, boosts your immune system, and restores your bones, muscles, and tissue.

Dreaming in non-REM sleep

Dreaming in non-REM sleep has been observed in scientific studies. Dreaming in non-REM sleep is determined by the proportion and distribution of two distinct types of slow waves.

Dream experiences are more likely to occur when the majority of slow waves are:

• Small
• Sparse
• Shallow
• Especially in posterior brain regions

The content of dream experiences is more likely to be reported if high-amplitude slow waves occur in frontocentral brain regions and are followed by high-frequency increases (local "microarousals").

While dreaming most commonly occurs during REM sleep, it can also happen during non-REM sleep. Dreaming during non-REM sleep is associated with specific characteristics in brain activity.

REM sleep is important for memory consolidation

Dreaming is a normal and healthy part of sleep, and it is during REM sleep that our most vivid dreams occur. But why do we dream, and what purpose does it serve?

While there is no clear answer to these questions, one theory is that dreaming is important for memory consolidation. Dreaming has been associated with the consolidation of memory, suggesting that it may serve an important cognitive function of strengthening memory and improving recall.

During REM sleep, the brain processes new learnings and motor skills from the day, deciding what to commit to memory, what to maintain, and what to delete. This process is similar to a librarian sorting and shelving books at the end of the day, making it easier to access and use learned information.

Research has shown that people who achieve REM sleep are better able to judge facial expressions and process emotions afterward. One study found that people who spent more time in REM sleep had lower fear-related brain activity when exposed to mild electric shocks the next day, suggesting that sufficient REM sleep may make a person less prone to developing post-traumatic stress disorder (PTSD).

Furthermore, studies have shown that being deprived of REM sleep interferes with memory formation. However, it is important to note that memory problems associated with a lack of REM sleep could be due to overall sleep disruption, as these two factors often occur together.

While the specific function of REM sleep and dreaming remains a mystery, it is clear that this stage of sleep plays an essential role in memory consolidation and emotional processing.

Dreaming is controlled by different brain mechanisms than REM sleep

Dreaming and REM sleep are indeed controlled by different brain mechanisms. While REM sleep is characterised by relaxed muscles, quick eye movement, irregular breathing, elevated heart rate, and increased brain activity, dreaming is controlled by forebrain mechanisms.

The cholinergic brain stem mechanisms that control the REM state can only generate the psychological phenomena of dreaming through the mediation of a second, probably dopaminergic, forebrain mechanism. This mechanism can also be activated by a variety of non-REM triggers. Dreaming can be manipulated by dopamine agonists and antagonists with no concomitant change in REM frequency, duration, and density. Dreaming can also be induced by focal forebrain stimulation and by complex partial (forebrain) seizures during non-REM sleep, when the involvement of brainstem REM mechanisms is precluded. Likewise, dreaming is obliterated by focal lesions along a specific (probably dopaminergic) forebrain pathway, and these lesions do not have any appreciable effects on REM frequency, duration, and density.

These findings suggest that the forebrain mechanism in question is the final common path to dreaming and that the brainstem oscillator that controls the REM state is just one of the many arousal triggers that can activate this forebrain mechanism. The "REM-on" mechanism (like its various non-REM equivalents) therefore stands outside the dream process itself, which is mediated by an independent, forebrain "dream-on" mechanism.

Lack of REM sleep can cause trouble coping with emotions

Dreaming is a normal and healthy part of sleep, but a lack of REM sleep can have adverse effects on our ability to process emotions. While REM sleep is not the only stage in which dreams occur, it is when the majority of dreams take place, and they tend to be more vivid and intense than non-REM dreams.

REM sleep is important for emotional processing. Dreams, particularly those in REM sleep, are thought to be involved in this process, as the brain activates the amygdala – the part that processes emotions. Studies have shown that a lack of REM sleep can cause an increase in negative self-appraisals and negative moods, as well as a decrease in positive self-appraisals. This means that not getting enough REM sleep can make it harder to cope with emotions, as you are more likely to view yourself and your situation in a negative light.

Furthermore, REM sleep deprivation can also cause an increase in the frequency of negative memories being recalled. This is because REM sleep plays a role in memory consolidation, and a lack of it can disrupt the brain's ability to form new cells. This disruption can lead to cognitive impairments, such as difficulty concentrating and forgetfulness, which can further impact your ability to process emotions in a healthy way.

Overall, while the specific function of dreaming is still not fully understood, the adverse effects of a lack of REM sleep on emotional processing are clear.

REM sleep is important for brain development

REM sleep is vital for the development of a healthy brain. Recent findings suggest that REM sleep is important for pruning and maintaining new synapses in the developing brain. This process is critical for normal neuronal circuit development and behavioural improvement after learning.

REM sleep is also important for memory consolidation and emotional processing, which are essential for brain development. During REM sleep, the brain processes new learnings and motor skills from the day, deciding which to keep and which to delete. It also plays a role in emotional processing by activating the amygdala, the part of the brain responsible for processing emotions.

REM sleep is especially important for infants and children, as their brains are still developing. Newborn babies spend eight hours in REM sleep each day, and this gradually decreases to an average of two hours per night by adulthood.

REM sleep deprivation can have negative consequences for brain development. Studies suggest that it interferes with memory formation and the brain's ability to generate new cells. Therefore, getting adequate REM sleep is crucial for promoting healthy brain development.

Frequently asked questions