growing evidence suggests that dreams — and, more so, sleep — are powerfully connected to the processing of human emotion.

adequate sleep may underpin our ability to understand complex emotions properly in waking life.

Participants who had reached REM sleep (when dreaming most frequently occurs) during their nap were better able to identify expressions of positive emotions such as happiness in other people, compared with participants who did not achieve REM sleep or did not nap at all.

Those volunteers were more sensitive to negative expressions, including anger and fear.

Walker suggests that one function of REM sleep — dreaming, in particular — is to allow the brain to sift through that day's events, process any negative emotion attached to them, then strip it away from the memories.

Past studies have also established a link between chronic sleep disruption and suicide.

sleep disruption contributing to the psychiatric disorder?