This study was performed to investigate the effects of shift-work, in terms of general health concepts, insomnia, stress, quality of life and psychological health, at several manufacturing plants.

Questionnaires were distributed to 850 shift-workers (study group), and to 550 non-shift workers (as a control group). The questionnaires included questions on ; general health concepts, insomnia, stress, quality of life and psychological health. 455 shift-workers and 372 non-shift workers completed the questionnaires, and the factors influencing the health status and quality of life in workers estimated by multiple iogistic regression analysis.

From the general health questionnaires, the mental health and health perception were significantly different between the shift and non-shift workers, with the better being former than the latter (p<0.05). Shift-workers complained of more insomnia when adjusted for age, working period, education and job satisfaction. Greater job satisfaction, was coupled with less complaints of insomnia (p<0.05). There were 200(43.96 %) shift workers classified as insomniac, whereas with the non-shift workers this figure was 84 (25.15 %), showing a significant difference between the two groups (p<0.05). Shift-workers were more stressed than the non-shift workers in their daily lives, which also showed significant difference (p<0.05). Less job satisfaction, was coupled with more complaints of stress (p<0.05). The quality of life of the shift-workers was lower than that of the nonshift workers (p<0.05). With the shift-workers complaining of more anxiety than the nonshift workers (p<0.05).

Our results suggest that shift-workers suffer from physical and psychological distresses, sleep problems and stress than non-shift workers. Furthermore, it is presumed that these factors might negatively affect the quality of life of shift-workers. Accordingly, interventional methods for shift-worker's health and quality of life as a result of adverse effects of shift-work are needed.