Factors Associated with Insomnia Among Truck Drivers in Japan

Purpose: Truck drivers with insomnia are at a high risk of traffic accidents. We aimed to investigate the prevalence of insomnia and identify its associated factors among truck drivers in Japan. Methods: Participants were 2927 male truck drivers younger than 65 years old. Self-administered questionnaires were used to assess insomnia symptoms, State-Trait Anxiety Inventory, drinking, smoking habits, body mass index, caffeine intake, as well as daily driving hours, consecutive days away from home, and driving distance. Insomnia symptoms included difficulty initiating sleep, maintaining sleep and early morning awakening. Insomnia was defined when any of these symptoms were observed with daily tiredness. Results: The prevalence of insomnia among the subjects was 13.3% (n=356), of which 13.5% had difficulty initiating sleep, 78% had difficulty maintaining sleep, and 26.4% had early morning awakening. After adjusting for covariates, drinking habits, daily driving hours, and STAI score were significantly and linearly associated with insomnia; the adjusted odds ratio (OR) of drinking habits for insomnia was 1.74 [95% confidence interval (CI), 1.23-2.47] for heavy drinkers compared to non-drinkers (trend p<0.001); the adjusted OR of daily driving hours was 1.87 (95% CI, 1.00-3.49) for 12 hours or longer in a day compared to <8 hours in a day (trend p<0.001); the adjusted OR of STAI quartiles was 5.30 (95% CI, 3.66-7.67) for the highest quartile compared to the lowest quartile (trend p<0.001). Conclusion: The present study demonstrated that insomnia is prevalent among truck drivers in Japan, and its risk factors include drinking habits, daily driving hours, and anxiety.