0140 The Relationship Between REM Sleep Prior to Analogue Trauma and Intrusive Memories

Introduction Intrusive memories are a core feature of posttraumatic stress disorder (PTSD). They both predict the onset of the disorder and drive broader PTSD symptomology. Three meta-analyses concluded sleep (vs wake) after exposure to an analogue trauma decreases the likelihood of intrusive memories. However, the role of sleep prior to analogue trauma exposure has not yet been examined. This is important, insomnia, OSA, and shift work prior to trauma exposure increases the risk of PTSD 2.5-3.0 fold. Given the role of REM sleep in emotion regulation, REM sleep prior to trauma exposure may be particularly critical in the development of intrusive memories. Here, we examined the association between REM sleep prior to analogue trauma and intrusive memories. Methods To manipulate REM sleep, 27 healthy adults (MAge = 25.4, SD = 2.89, 56% Female) were randomised to either to a circadian misalignment (CM) condition or normal control (NC) condition for four nights. In CM, participants slept normally for two nights followed by a 4-hour phase advance on night three and an additional 4-hour phase advance on night four. In NC, participants had 8-hour sleep opportunities each night. On day 5, participants watched a trauma film and kept an intrusive memory diary for the next three days. Analyses focused on the relationship between REM sleep over 4 nights in the lab and subsequent intrusive memories. Results Greater REM sleep percentage (p = .004) and REM efficiency (p = .02) across 4 nights prior to analogue trauma, independent of group, were significantly associated with fewer intrusive memories in the 3 days after viewing the film. Conclusion Findings suggest REM sleep may serve to protect individuals against experiencing intrusive memories. This is consistent with evidence suggesting REM sleep influences emotional memory regulation. Occupations (e.g., emergency services/military personnel) who experience circadian disruptions likely to decrease REM sleep (e.g., from shift work) may be at heightened risk of experiencing intrusive memories after trauma exposure, and thus at increased risk of developing PTSD. Support (if any) US Department of Defence office of the Congressionally Directed Medical Research Programs (ID number: PR170893PI)