London: Dreams are a gateway to grapple the inner turmoil human beings face in their lives, reveals a new study. Scientists have found that dreaming is essential to cope with emotional stress, a newspaper reported.

Researchers from the University of California - Berkeley found that our brains process emotional experiences during dreams and this takes the painful edge off difficult memories.

The team studied 35 healthy young adults, divided into two groups. All of them viewed 150 emotional images, twice and 12 hours apart, while an MRI scanner measured their brain activity.

Half of the participants viewed the images in the morning and again in the evening, staying awake between the two viewings. The remaining half viewed the images in the evening and again the next morning after a full night of sleep. Those who slept in between image viewings reported a significant decrease in their emotional reaction to the images.

The MRI scans showed that sleep caused a dramatic reduction in reactivity in the amygdala, a part of the brain that processes emotions.

This allowed the brain's rational pre-frontal cortex to regain control of the participants' emotional reactions. The overnight recordings of the participant's electrical brain activity showed levels of stress neurochemicals reduced while asleep.

The findings explained why people with post-traumatic stress disorder (PTSD) suffer recurring nightmares.

The researchers said the therapy element of sleep may malfunction in PTSD sufferers. Therefore, when a flashback is triggered by, say, a car backfiring, they relive the whole experience because the emotion has not been properly stripped away from the memory during sleep.

'Dreaming is vital in softening the emotional strength of experiences, we feel better about them, we feel we can cope with them,' said Mathew Walker, researcher who led the study.

While we spend one-third of our lives sleeping, there is no scientific consensus on the function of sleep.

(Agencies)