That doesn't mean they buried their fury: Men and women who recovered best actually had dreams showing stronger emotions, such as anger, about their exes. But they also took more active roles in their dreams and wove in memories that felt similar — for example, of earlier abandonment experiences. Linking past challenges with the present one may help dreamers recover by showing that they have survived similar crises that felt somewhat like this one, Cartwright says.
Further suggestive evidence that dreams might affect recovery from trauma — for good or ill — comes from a study of 39 injured survivors of life-threatening accidents. A couple of months after their accidents, those who had continued to dream about the traumatic event showed the most severe post-traumatic stress disorder symptoms, whereas others who couldn't recall dreams or dreamed about different topics were in better mental health, says psychiatrist Thomas Mellman of Howard University School of Medicine in Washington, D.C. "This suggests it may help to process trauma if people dream in more metaphoric ways or don't recall dreams at all," he says. "Dreams that keep you stuck in the actual incident don't seem to be adaptive."
Such studies don't, of course, prove that the dreams actively helped. But those who study dreams note that the brain in REM sleep (when most dreams occur) is in a somewhat different state: The visual cortex is much more active. At the same time, there's less activity in the brain's prefrontal cortex, the seat of planning, conventional assumptions and censorship. This different state might facilitate new ways of thinking about problems.