Investigating the relationship between sleep quality and intrusive memories in post-traumatic stress disorder

The Sleep to Forget, Sleep to Remember model (Walker, 2009) suggests that sleep quality influences emotional memory consolidation. This model has relevance to intrusive memories in PTSD, since theories of PTSD posit that intrusive memories are a product of inadequate processing of emotional memories (Brewin, Dalgleish, & Joseph, 1996; Ehlers & Clark, 2000). The present study aims to investigate the moderating effect of sleep on the relationship between PTSD and intrusive memories. 34 PTSD, 44 trauma exposed (TE) and 40 non-trauma exposed (NTE) participants completed an emotional memory task, where they viewed 60 images (20 positive, 20 negative and 20 neutral) and, two days later, reported how many intrusive memories they had of each valence category. Participants also completed three measures of sleep quality: the Pittsburgh Sleep Quality Index, the REM Behaviour Disorder Screening Questionnaire and total hours slept before the second session. The PTSD group reported poorer sleep quality than control groups on all three measures, and significantly more negative intrusive memories than the NTE group. Moderation analyses revealed that hours of sleep before the second session moderated the relationship between PTSD symptomology and intrusive memories, as predicted by Sleep to Forget, Sleep to Remember (Walker, 2009).