The Relationship between Chronotype and Sleep Quality in Korean Firefighters

OBJECTIVE We examined the relationship between chronotype and sleep disturbance, and assessed various factors that might be associated with sleep disturbance in Korean firefighters. METHODS Self-administered questionnaires assessing chronotype, depression, alcohol use, posttraumatic stress disorder (PTSD), stress response and sleep quality were examined in 515 firefighters. RESULTS Evening type firefighters more reported depression, alcohol use, PTSD, stress response and sleep disturbance. Also evening chronotype was the most significant risk factor for poor sleep quality (odds ratio [OR], 4.812; 95% confidence interval [CI], 2.448-9.459), even after controlling for all other variables (OR, 3.996; 95% CI, 1.806-8.841). CONCLUSION Chronotype was the factor most strongly associated with sleep disturbance, and therefore should be considered an important variable in sleep quality, particularly in occupations involving stressful activities, such as firefighting.