A research team from The University of California showed a group of participants a series of emotional images and then scanned them a few hours later as they viewed the images for a second time.
Between the two showings half of the participants were allowed to sleep and half were not.
When assessing the results of the scan it was found that the participants who were allowed to sleep between the showings were less active in the amygdala – the area of the brain linked to heightened emotions, and more activite in the prefrontal cortex – a brain region linked to rational thinking.
The group who were not allowed to sleep on the other hand, experienced a much more emotional response to the second round of pictures.
Scientists who worked on the study believe that the changes that occur during the REM period of sleep could help to explain why painful memories seem to be eased by sleeping.
The scientists believe that chemical changes in the brain during REM sleep may help to explain how the body makes this change.
Study leader Dr Matthew Walker has said that during the REM stage of sleep there is a decrease in a brain chemical which is associated with stress – norepinephrine.
He commented, “By reprocessing previous emotional experiences in this neurochemically safe environment of low norepinephrine during REM sleep, we wake up the next day, and those experiences have been softened in their emotional strength.”
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