Rapid eye movement sleep may be just what the doctor orders for people with posttraumatic stress syndrome, according to a new study from the University of California at Berkeley. The problem is that the symptoms of posttraumatic stress syndrome include nightmares, insomnia, and other sleep disturbances - meaning that victims are often naturally deprived of the very sleep that could cure their condition. Rapid eye movement or REM sleep takes up 20% of a normal person's sleeping hours, and is the kind of sleep that produces dreaming. The Berkeley research team, led by Prof. Matthew Walker, found that during REM sleep certain electrical activity patterns decrease in the brain, and there is also a sharp decrease in levels of stress neurochemicals. Fewer amounts of such chemicals reduce the emotional reactions to whatever the person experienced in the daytime. "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," said Dr. Walker. "We know that during REM sleep, there is a sharp decrease in levels of norepinephrine, a brain chemical associated with stress." Blood pressure medicines can also suppress norepinephrine in the brain. For the Berkeley study, which was published in the journal Current Biology, 35 young adults were divided into two groups. After being hooked up to magnetic resonance imagining (MRIs) technology, they viewed 150 emotional pictures in two sessions 12 hours apart. Half of them looked at the images in the morning and then at night. The other group looked at the pictures at night, then went to sleep and returned to the lab the next day to view them again. The group that got to sleep between viewings were less emotional in their reaction to the pictures. The researchers monitored participants while they slept, and found that the second group was able to process the emotional content of the pictures during REM sleep. "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," said Prof. Walker. "We feel better about them, we feel like we can cope." Prof. Walker believes that people suffering from posttraumatic stress syndrome may have experienced some kind of breakdown in the natural function of REM sleep. "When a flashback is triggered by -say, a car backfiring," he said, "they relive the whole visceral experience once again, because the emotion has not been properly stripped away from the memory during sleep." Other experts, including Dr. Roderick Orner, disagree, noting that other factors besides sleep may be involved in posttraumatic stress syndrome. "In cases of severe trauma," Dr. Orner said, "it may be just too difficult for the patient to process it during sleep, especially if that event had a significant impact on that person's day to day life." One form of popular new therapy for post-traumatic stress syndrome is called Rapid Eye Movement Desensitization and Reprocessing, in which the patient recalls the event that had caused him extreme trauma while watching an object oscillate back and forth. Each session lasts less than 30 seconds. After the recollection session ends, the patient discusses the memory with a therapist. This type of therapy using rapid eye movement has proven very effective in the short run, and can work much faster and at a lesser cost than ordinary psychotherapy. However, there are no current long-term studies that prove the positive outcomes are permanent.