Circadian instability predicts PTSD symptom severity following mass trauma

ObjectiveTrauma exposure may lead to posttraumatic stress disorder (PTSD) in a subset of vulnerable individuals. Circadian rhythm disruptions have emerged as both risk factors and consequences of PTSD. Whether circadian disruptions in trauma aftermath predict future PTSD risk, and if so, what behavioral and physiological indices of circadian disruption underlie risk prediction, is not yet clear. MethodsSurvivors of the Supernova music festival mass trauma event (n=211) were monitored in real-life settings for a full month, three-to-six months post-event, using wearable sensors that tracked their heart rate (HR), activity and sleep. PTSD symptoms were assessed using the Posttraumatic Checklist for DSM-5 (PCL-5) before and after the recording month, as well as at follow-up eight-to-eleven months post-event. Matched controls (n=113) underwent an identical procedure. Behavioral and physiological indices of circadian rhythm disruptions were quantified using interday sleep stability and cosinor HR analysis, respectively. Linear regressions tested associations between circadian measures and PTSD status and severity at follow-up. ResultsCompared to controls, trauma survivors exhibited circadian instability three-to-six months post-event, expressed behaviorally as reduced interday sleep stability and physiologically as higher variance in daily HR phases. Critically, 54% of trauma survivors exceeded the clinical threshold for PTSD at follow-up. Circadian instability three-to-six months post-event was particularly potent among survivors with PTSD at follow-up and predicted their symptom severity. ConclusionsSpecific behavioral and physiological indices of circadian instability three-to-six months post-trauma predict future PTSD risk. Maintaining stable circadian rhythms in trauma aftermath may mitigate PTSD symptoms, highlighting avenues for monitoring and early interventions.