O006 A double-blind randomized placebo-controlled trial on the effect of suvorexant on REM sleep and fear extinction recall

Abstract Disturbed sleep is common after trauma exposure. Individuals seeking relief may consult their GP and are frequently prescribed benzodiazepines. However, these drugs are detrimental as they can impair extinction processes (i.e., the reduction of the conditioned fear response to trauma-related stimuli over time) and thus increase the risk of developing post-traumatic stress disorder (PTSD). Additionally, benzodiazepines may disrupt rapid eye movement (REM) sleep, which is crucial for consolidating emotional memories. Therefore, this study explored suvorexant as a potential alternative to increase REM sleep and improve extinction consolidation compared to temazepam and placebo. Thirty healthy adults (age M=26.23, SD=7.55) completed a two-day fear conditioning paradigm, receiving either drug (double-blinded) before in-lab overnight PSG and returning for extinction recall testing 48h later. There was no significant difference between groups in REM sleep, F(1, 28)=0.01, p=.94. However, there was a significant effect for REM sleep (p=.01) and a REM by drug interaction (p<.01) on extinction recall. Post-hoc tests revealed that in the placebo group, increased REM sleep was associated with a reduced fear response indicative of better extinction recall (p=.01), with no association found in the other conditions (p>.05). Despite unsuccessful REM sleep manipulations, results suggest that in PTSD with disrupted REM sleep, suvorexant might mimic the effect seen with placebo in healthy controls, leading to improved extinction recall. However, this needs to be replicated in a clinical PTSD sample. If confirmed, suvorexant may reduce the risk of PTSD development through improving sleep-dependent extinction processes, thus offering a viable alternative to harmful benzodiazepines.