Subjective sleep parameters: A marker to PTSD symptoms evolution? A 4-year longitudinal study.

Disturbed sleep is a common feature after exposure to a traumatic event, especially when PTSD develops. However, although there is evidence suggesting a potential role of sleep disturbance in the progression of PTSD symptoms, the interrelationship between sleep and PTSD symptoms has yet to be determined. In order to address this knowledge gap, we have investigated the influence of initial sleep characteristics on the evolution of post-traumatic stress disorder (PTSD) symptoms over 4 years of follow-up among individuals exposed to the Brazilian Kiss nightclub fire. Participants were individuals exposed to the 2013 Kiss nightclub fire in Brazil. Sleep characteristics and PTSD symptoms were measured within the 4 years following the fire by self-report questionnaires, such as The Pittsburgh Sleep Quality Index (PSQI), and PTSD Checklist - Civilian version (PCL-C). Generalized estimating equations (GEE) models were used to examine the longitudinal associations (by estimating the relative effects of initial sleep problems on PTSD symptoms after adjusting for covariates). Comprehensive information concerning socio-demographic factors, health status, and sleep complaints were obtained. A total of 232 individuals were included. In GEE models, no significant interactions were observed between sociodemographic variables and PTSD symptoms in the follow-up period, however, associations were found between PTSD at baseline and the following factors: the female gender, the victim individuals and the existence of prior psychiatric disease. Initial subjective sleep parameters were strongly associated with PTSD symptoms over 4 years, mainly the presence of disturbed dreams (p = 0.012), increased sleep latency (p = 0.029), and reduced sleep duration (p = 0.012). Sleep complaints and PTSD symptoms were common among individuals after the disaster. The current study has found that the presence of sleep complaints, especially increased sleep latency, presence of disturbed dreams and short sleep duration, in the initial presentation after the fire was consistently associated with the perpetration of PTSD symptoms in the next 4 years of follow-up. These findings suggest that interventions addressing these sleep complaints have the potential to reduce the persistence and/or severity of PTSD symptoms.