How many truck drivers have sleep disorders? Investigation of the effects of lifestyle and stress on insomnia among Japanese male truck drivers

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.