Whether you remember having a good dream or a nightmare just after waking up, new research shows that the brain “sorts emotions” during dreams: consolidating positive emotions and suppressing negative ones, again underscoring the importance of sleep for mental health.
Rapid eye movement (REM) is a unique and mysterious sleep state that produces dreams with intense emotions, but how and why these emotions are activated is unclear. In the past, the prefrontal cortex (PFC) was known to process many strong emotions during wakefulness, but paradoxically quieted down during REM, so the team at the University of Bern wanted to understand the underlying mechanisms and functions behind this phenomenon.
Distinguishing between the emotions of danger and safety is crucial for animal survival. For humans, excessive negative emotions such as fear and anxiety may further lead to serious mental illness, but there is always a chance to get better after a “sleep”. The team of neuroscientist Antoine Adamantidis at the University of Bern found that REM sleep can help to enhance positive emotions, while at the same time weakening emotions in highly negative or traumatic stress disorder.
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Rem Sleep Experiment Results
In experiments with mice, the researchers exposed the mice to safe auditory stimuli and dangerous (aversive) auditory stimuli, then recorded neuronal activity in the mice’s brains during the sleep-wake cycle, mapping different regions of the cells and how emotional memory during REM change.
The results of the study found that when the neuron dendrites were activated, the cell body (soma) remained silent, indicating that both were clearly part of the neuron structure, but were obviously “uncoupled” during REM: the cell body was completely asleep, and the dendrites were completely asleep. This decoupling behavior is important because strong dendrites can process danger and safety-related emotions, while cell body inhibition completely blocks circuit output. That is, the brain is sorting safety and danger emotions during this period, but preventing Overreacting to emotions, especially bad ones.
The team said that the coexistence mechanism of the cell body being completely asleep but the dendrites being fully awake is beneficial for the organism to maintain mental stability and survive. If human neurons lack this mechanism and produce excessive fear responses, it may cause anxiety disorders.
The discovery that sleep processes emotion also opens up new therapeutic directions for the treatment of traumatic stress disorder (PTSD) and explains why sleep is so reliant on early onset. Other acute/chronic psychological disorders may also be involved, such as stress, anxiety, depression, panic attack , anhedonia (i.e. the inability to experience pleasure), etc.
The importance of REM sleep for the body and mind
To this day, it has not been conclusively clarified what the significance of the REM phase during sleep is. What is certain is that REM sleep is the time when dreams are most intense. Blood pressure and pulse rise, as does brain activity .
Also, paralysis of the body occurs during REM sleep. The purpose of this is that the sleeping person does not actually carry out the movements that he dreams about. It is likely that the REM sleep phase is related to the learning process and long-term memory.
There is a widespread belief that REM sleep is restorative or particularly healthy. However, there is no scientific evidence that REM sleep is more important than other sleep stages. Also, lack of REM sleep does not affect everyone in the same way.
Is REM sleep deep sleep?
No, the REM sleep phase is different from the deep sleep phase. In deep sleep, bodily functions are reduced and the sleeper usually lies very still – in contrast to REM sleep with increased heart rate and blood pressure as well as rapid eye movements.
How can I improve my REM sleep?
Since all stages of sleep are affected by overall sleep quality, it is not possible to specifically improve the quality of REM sleep. However, measures that lead to better sleep overall can also have a positive effect on REM sleep. Such measures are, for example:
- regular sleeping and waking times
- Avoiding physical activity just before bedtime
- Avoiding alcohol and heavy meals in the evening
- Constant room temperature
- Relaxation exercises before bed
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The article is published in the journal Science.
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