OBJECTIVES: This study aimed to investigate how many male truck drivers have sleep disorders and what factors are most associated with chronic insomnia symptoms. METHODS: A cross-sectional study of 505 truck drivers in Akita prefecture was conducted using a self-administered questionnaire and health checkup data. We defined insomnia based on the International Classification of Sleep Disorders, third edition, sleep apnea syndrome (SAS) with a simple 4-variable screening tool, and restless legs syndrome (RLS) with RLS/Willis-Ekbom disease diagnostic criteria. Investigated factors included sleep duration, driving characteristics, caffeine types (foods and beverage) and amounts, caffeine intake timing, State-Trait Anxiety Inventory (STAI), individual stress, and other covariates. RESULTS: The prevalence of suspected SAS was 23.2% (n = 154), and that of RLS was 0.8% (n = 5). After excluding those, chronic insomnia symptoms were present in 36/505 drivers (7.1%). After adjusting for covariates, a logistic model demonstrated that drinking habits [odds ratio (OR), 6.21
95% CI, 1.07-35.8], caffeine intake before sleep (OR, 2.65
95% CI, 1.09-6.45), sleep duration on days off (OR, 1.44
95% CI, 1.01-2.05), and STAI score (OR, 12.8
95% CI, 2.53-64.2) were significantly associated with chronic insomnia symptoms. STAI was significantly positively correlated with individual stress, such as family worries (r = 0.22), relationships with non-partners (r = 0.28), and health (r = 0.23). CONCLUSIONS: Our study revealed that one-fourth of male truck drivers had sleep disorders that require further medical evaluation. For male truck drivers, lifestyle modification and stress relief may be key to address insomnia.