REM theta activity predicts re-experiencing symptoms after exposure to a traumatic film

Extensive empirical evidence indicates that sleep plays an active role in memory consolidation. Moreover, sleep has been found to preferentially enhance emotional memories and may modulate affective reactions to previously encountered stimuli. Notably, recent findings suggest that disruptions of sleep-related memory processing could be involved in posttraumatic symptom development such that sleep disturbances may accelerate symptoms of intrusive re-experiencing.

Based on this emerging evidence, we investigated whether an analogue traumatic event would result in immediate impairments of sleep quality in a group of healthy, robust sleepers. In addition, we examined associations between a specific oscillatory correlate of emotional memory consolidation processes (REM theta activity) and subsequent analogue PTSD symptoms. Thirty-three healthy participants entered the study and were exposed to either "traumatic" or neutral films. Thereafter, participants were subjected to an 8.5-hour-long nocturnal sleep opportunity under standardized laboratory conditions including full-night polysomnographic recordings. Ambulatory intrusive memories and subjective symptom ratings were assessed during a period of three consecutive days.

Our results provide partial support for impaired sleep quality after exposure to a traumatic film. Correlation analyses further reveal that a longer REM sleep duration after "traumatic" exposure predicts reduced analogue PTSD symptoms. Critically, REM theta activity selectively predicts lower re-experiencing symptoms. As previous findings suggest that REM theta activity is reduced in patients with posttraumatic stress disorder, our findings provide a new perspective on the functional role of REM sleep in trauma memory processing.