One of the purposes of dreaming is to take the edge off emotional memories, research suggests.
While dreaming, which we do during 20% of our sleep, the brain chemistry related to stress powers down.
This enables us to process emotional memories without the same jolts of fear and anxiety.
People in the study who looked at a series of emotional images felt much less disturbed by them after sleeping.
Those who looked at them in the morning first, then in the evening, without sleeping, reported a higher emotional reaction.
Brain scans also showed lower emotional reactivity in the amygdalas of those who slept.
Dr Matthew Walker, who led the study, said:
“The dream stage of sleep, based on its unique neurochemical composition, provides us with a form of overnight therapy, a soothing balm that removes the sharp edges from the prior day’s emotional experiences.”
The research was inspired by the treatment of war veterans experiencing post-traumatic stress disorder.
This type of dream therapy may be inefficient in veterans since when a…
“…flashback is triggered by, say, a car backfiring, they relive the whole visceral experience once again because the emotion has not been properly stripped away from the memory during sleep.”
Dr Els van der Helm, the study’s first author, said:
“During REM sleep, memories are being reactivated, put in perspective and connected and integrated, but in a state where stress neurochemicals are beneficially suppressed.”
Dr Walker explained that the research was inspired by the side-effect of a blood pressure drug.
It happened to reduce levels of norepinephrine in the brain.
Dr Walker said:
“We know that during REM sleep there is a sharp decrease in levels of norepinephrine, a brain chemical associated with stress.
By reprocessing previous emotional experiences in this neuro-chemically safe environment of low norepinephrine during REM sleep, we wake up the next day, and those experiences have been softened in their emotional strength.
We feel better about them, we feel we can cope.”
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The study was published in the journal Current Biology (ven der Helm et al., 2011).