Unpleasant experiences could be countered by a good night's sleep paradoxical

A team of researchers from the Dutch Institute of Neuroscience discovered that a restful night with a good REM sleep (Rapid Eye Movement) could neutralize the effects of unpleasant experiences and memories. They found the reason for such an adaptation. Their study titled "Paradoxical Rest Hinders Tonsil Overnight Adjustment" was published in the latest issue of the journal Current biology.

The team of researchers concluded that emotional experiences often trigger an "amygdala activation". Unpleasant experiences cause emotional distress in all individuals. This triggers the brain circuits mainly in the "limbic system". Several studies have shown that sleep helps to recover from this distress. Therefore, sleep can produce a "time window" for the reorganization of these activated circuits.

Their study revealed that having a night with a good amount of REM sleep can help adapt the amygdala to the next day. Having good-quality slow-wave sleep or NREM sleep prior to REM sleep also facilitates the adaptation of the limbic system. When paradoxical sleep is disturbed or agitated, the team writes that the amygdala's adaptation has failed.

The researchers explain that having a restless paradoxical sleep is characteristic of many psychiatric disorders, including insomnia and post-traumatic stress disorder. According to them, this could be due to "insufficient silence of locus coeruleus (LC) during REM sleep". This insufficient silence of the LC is responsible for inadequate recovery of the brain after a night of restorative sleep. The team wrote that the amygdala is the "siren of the brain". Its subsequent inhibition during restorative sleep is responsible for the dissolution of distress. This means that the person regains his normalcy after an unpleasant experience due to the adaptation of the amygdala.

To study their hypothesis, the team included 29 participants to study the impact of an unpleasant emotional experience on REM sleep and limbic response with the help of the 39 Functional Magnetic Resonance Imaging (fMRI). The severity of insomnia among these participants varied. Awakening and sleep pattern were badessed by electroencephalography (EEG). The goal was to determine if the activity of the amygdala was related to restful sleep and whether the reorganization of amygdala activity was hampered by sleep interruptions.

The team found that the amygdala's reactivity decreased overnight in the event of a decrease in total REM sleep. They write, "Restless REM sleep prevented amygdala adjustment overnight."

The team then used odors or smells that were badociated with unpleasant emotional experiences. These smells have been targeted to trigger unpleasant memories and reduce REM sleep. The results showed that a good REM was actually responsible for adjusting the amygdala. The team wrote that "a type of maladaptive sleep" could be "a target for interventions in mental disorders characterized by restless REM sleep".

For their olfactory experience, the team used a specific smell badociated with a shattering memory. As soon as the participant has felt this smell, he or she has shown activity in the brain scan in the amygdala area. Then they spent the night in the sleep labs and an EEG measured their brain waves. Brain waves are typical of different phases of sleep. During their sleep, they were again exposed to this odor. The next morning, in the awakened state, the same unpleasant experience was presented again. This time, the brain had adapted overnight for those who had good REM sleep. This meant that they no longer reacted to unpleasant experiences. Some participants were restless sleepers. Among them, there was no recovery of the amygdala at night when these people were exposed to the smell and again experienced distress. This proves that it is restorative sleep that helps the brain circuits to recover overnight.

The team wrote that some of the neural connections related to pleasant or unpleasant memory during the day could be strengthened or weakened during nighttime sleep. This was also disturbed if sleep was agitated.

According to the study's researchers, Rick Wbading, Frans Schalkwijk and Eus van Someren, diagnose a restless REM and target this phase of sleep could help patients with insomnia and PTSD, but also the help better manage unpleasant experiences.

The authors wrote: "REM sleep can promote nocturnal regulation of amygdala responsiveness. The effect increases with earlier longer episodes of transition to REM, but is interrupted by interruptions in REM sleep. They add that people with PTSD or "adversity of early childhood" could have chronic and agitated REM. They conclude, "Addressing the processing deficits of day-to-day emotional memory in these disorders is likely to provide clues to the underlying mechanisms of hyperexcitation, which are up to the point of failure." present remained enigmatic. "