Dreams help in emotional purge

Why sleeping on a problem is best

Sunday 27 November 2011

Sleeping on problem really does help because dreaming provides overnight therapy for painful memories, a California University study has found.

Photo: ALAMY



By Nick Collins, Science Correspondent

7:30AM GMT 24 Nov 2011
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When we enter the dream stage of sleep, known as REM, the stress systems in our brain become deactivated while our brain runs over recent emotional memories.

Brain scans showed that after sleeping, the emotional centre of the brain becomes less active while areas that govern rational thought take over, helping us to get over painful experiences from the previous day.

The study could explain why post-traumatic stress disorder victims, who typically suffer from disturbed sleep, have severe difficulty overcoming painful memories, experts said.

Although there is no scientific consensus on exactly why we spend a third of our lives sleeping, the study adds to growing evidence on the importance of the REM phase, which takes up 20 per cent of our total sleep.

Matthew Walker, senior author of the study, said dreaming "provides us with a form of overnight therapy, a soothing balm that removes the sharp edges from the prior day's emotional experiences.

"By reprocessing previous emotional experiences ... 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," he added.

Researchers from the University of California, Berkeley, monitored the brain activity of 34 volunteers with MRI scanners while they were shown a series of 150 images designed to provoke an emotional response.

The test was carried out twice with a 12 hour period in between – but while half the participants saw the images in the morning and again that evening, the other half started in the evening and had a full night's sleep before their second viewing.

Results showed that those who slept between their two scans had a much lower emotional reaction when viewing the pictures for the second time.

Brain scans identified a drop in activity in the amygdala, part of the brain which controls emotions, and an increase in the prefrontal cortex, which governs rational responses, compared with the previous evening.

Els van der Helm, a doctoral student who led the study, said: "During REM sleep, memories are being reactivated, put in perspective and connected and integrated, but in a state where stress neurochemicals [chemicals in the brain] are beneficially suppressed."

The researchers said the study, published in the Current Biology journal, could explain why blood pressure drugs which suppress stress signals in the brain during sleep have proved effective in some post-traumatic stress disorder patients, and may lead to new treatments for sleep disorders and mental illness.
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telegraph.co.uk/science/science-news/8910111/Why-sleeping-on-a-problem-is-best.html