A study of the impact of occupational and domestic factors on insomnia among industrial workers of a manufacturing company in Japan.

Insomnia is one of the most common health problems and has recently been re-termed 'Disorders of initiating and Maintaining Sleep', or DIMS. The main purpose of the present study was to investigate the relationship between daily psychosocial stressors, to which workers are exposed in occupational and/or private life, and insomnia among male industrial workers in a medium-sized company located in Nagasaki City, Japan. All of the workers in the company (n = 368, male = 319) were asked to answer six sleep related questions and 24 questions about working and private conditions. Two hundred and seventy-one (85.0%) of them completed the questionnaire (average age was 40.9 years old). Twenty seven point seven per cent of the subjects complained of insomnia in the last month prior to the survey and the prevalence was in general accord with previous surveys. On the other hand, the proportion of hypnotic use (1.1%), especially in insomniac group (2.7%) was lower than previous reports. The results of multiple logistic regression analysis demonstrated that four psychosocial factors were significantly associated with insomnia: i.e. VDT work overload (odds ratio [OR] 5.058; 95% confidence intervals [95% CI] 2.381-10.745), limited space of bedroom (OR 2.612; 95% CI 1.283-5.683), over-involvement in job (OR 2.78; 95% CI 1.188-6.540), frequent alcohol beverages consumption (OR 2.595; CI 1.77-5.719).