This study aimed to investigate the correlation between chronotypes and posttraumatic stress disorder (PTSD) symptoms in medical students affected by earthquakes in Kahramanmaraş, Turkey, while elucidating if the PTSD manifestation varies among different chronotypes four months post-disaster. The study encompassed 193 medical students, subjected to the sociodemographic data form, the Morningness-Eveningness Questionnaire (MEQ) and the PTSD Checklist for DSM-5 (PCL-5). The results indicated that students identified as "evening types" reported significantly elevated PCL-5 scores (p < 0.001) relative to "morning" and "intermediate" types. According to PCL-5 scores, 43.5% of the participants exhibited PTSD, with a higher occurrence among the evening types. Multivariable linear regression analysis revealed that lower MEQ scores independently correlated with elevated PTSD symptoms (β = -0.1389 [95% CI = -0.273 - -0.0048], p = 0.042), suggesting the potential of eveningness as a risk factor for PTSD post-disaster. These findings could enhance our understanding of PTSD, aid the development of preventive strategies, and underscore the importance of considering chronotypes. Further expansive, population-based studies with a longitudinal design are necessary to better understand the relationship between PTSD and the circadian system.
Keywords: Chronotypes; circadian system; earthquake; morningness-eveningness; posttraumatic stress disorder.