To determine the depressive symptoms and their association with sleep quality, occupational stress and fatigue among small-scale manufacturing male workers.

A self-administered questionnaire was distributed to 856 workers employed in 62 work places under 50 members of manufacturing industries from April 1st to June 30th, 2010. The questionnaire survey included sociodemographic and health-related characteristics, job-related characteristics, sleep quality (PSQI), occupational stress (KOSS), fatigue symptoms (MFS) and depressive symptoms (CES-D).

Among all subjects, 44.3% were in the depression group (21 points and over in the CES-D score), and it was positively correlated with occupational stress, fatigue and quality of sleep. The adjusted odds ratios for the effect of depression on sleep quality, occupational stress and fatigue were significantly increased in the high risk group compared to that in the normal group. Hierarchial multiple regression analysis revealed that the following factors of influence had combined explanatory powers of 49.3% on depression: marital status, BMI, subjective status of health, leisure time, job position, job tenure, sense of satisfaction in work, quality of sleep, occupational stress and fatigue.

The study results revealed a very complicated influence exerted on the level of depression by variable factors, as well as sociodemographic characteristics, health related characteristics and job-related characteristics, particularly quality of sleep, occupational stress and fatigue. Especially, the level of depression was more influenced by occupational stress than by quality of sleep and fatigue factors.