Restless REM sleep a risk for many mental disorders?
Upset by something unpleasant? We have all been there. Fortunately, it also passes. A new day, a new beginning. At least: if you have restful REM sleep. Researchers Rick Wassing and Eus van Someren from the Netherlands Institute for Neuroscience and Amsterdam Neuroscience discovered why you will be better able to bear tomorrow what you are distressed about today. And why that can go wrong.
Siren of the brain
Something frightening or unpleasant does not go unnoticed. In our brain, the so-called limbic circuit of cells and connections immediately becomes active. First and foremost, such experiences activate the amygdala. This nucleus of brain cells located deep in the brain can be regarded as the siren of the brain: attention! In order for the brain to function properly, the siren must also be switched off again. To do so, a restful REM sleep, the part of the sleep with the most vivid dreams, turns out to be essential.
Neuronal connections weaken and strengthen
During sleep, 'memory traces' of experiences from the past day are spontaneously played back, like a movie. Among all remnants of the day, a specific memory trace can be activated by presenting the same odor as the one that was present during the experience while awake. Meanwhile, memory traces are adjusted during sleep: some connections between brain cells are strengthened, others are weakened. Restless REM sleep disturbs these nocturnal adjustments that are essential for recovery and adaptation to distress.
The findings can be of great importance for about two-thirds of all people with a mental disorder, as both restless REM sleep and a hyperactive amygdala are the hallmarks of post-traumatic stress disorder (PTSD), anxiety disorders, depression and insomnia. Authors Rick Wassing, Frans Schalkwijk and Eus van Someren predict that treatment of restless REM sleep could transdiagnostically help to process emotional memories
overnight and give them a better place in the brain.