P127 Study protocol for examining the role of REM sleep in trauma-recovery mechanisms: REM fragmentation and fear inhibition in adults with insomnia disorder before and after cognitive behavioural therapy for insomnia (CBT-I)

INTRODUCTION: Insomnia has been shown to increase by 2.5-3 fold the risk of developing posttraumatic stress disorder (PTSD) after a traumatic event. The mechanism underlying this increased risk, however, remains unknown. We postulate insomnia may be contributing to PTSD by disrupting rapid eye movement (REM) sleep in the same way it has been shown to impair fear inhibitory processes, which are central to the natural recovery from trauma. To test this, the following protocol aims to: (1) examine the relationship between REM sleep fragmentation and fear inhibition in insomnia; and (2) examine whether correcting REM fragmentation by treating the insomnia, in turn, improves fear inhibition. METHODS: Ninety-two adults with insomnia disorder will be randomly allocated to an active treatment or waitlist control condition. Active treatment involves 7 weekly sessions of cognitive behavioural therapy for insomnia (CBT-I) with a clinician via telehealth. REM fragmentation and fear inhibition (i.e., safety learning and extinction recall) will be assessed pre- and post-treatment in a 4night/3day testing protocol via at-home polysomnography and the fear-potentiated startle paradigm, respectively. DISCUSSION: This study aims to be the first to test an underlying mechanism potentially explaining why insomnia greatly increases PTSD risk, while demonstrating an existing clinical intervention (CBT-I) can be used to improve this mechanism. Findings will have potential clinical implications for novel approaches in the prevention, early intervention, and treatment of PTSD.