Objective The goal of the present study was to investigate the roles of situational (ie, psychophysiological reactivity to acute stress) and dispositional variables (ie, neuroticism, coping styles) in shaping the effects of acute stress exposure on REM sleep.

Methods Sixty-three healthy young adults slept in the laboratory after being randomized into CTL or EXP. Measures of psychophysiological reactivity (state anxiety, stress level, and mean arterial blood pressure) were collected before and immediately after randomization. All subjects completed the Neuroticism-Extroversion-Openness-Personality Inventory Revised and the Ways of Coping Checklist.

Results A significant stress exposure by REM period interaction was found, and average RCs in the last REM period were significantly lower in EXP compared with CTL subjects (p = .005). The global slope of increase in average RC across successive REM sleep periods was less steep in EXP compared with CTL subjects (p = .02). Late-night RC was mediated by changes in subjective stress level from baseline to task notification, whereas REM latency was predicted by changes in state anxiety. Neuroticism and coping style did not directly moderate the effects of acute stress exposure on REM sleep. Rather, social coping and avoidance moderated psychological reactivity.

Conclusions The findings suggest that attenuation of REM sleep phasic activity after stress exposure may reflect adaptive regulation of waking emotional arousal. Mediation and moderation models are more informative than traditional bivariate approaches to investigating the relation between stress exposure and sleep alterations.