Lifestyle and work predictors of fatigue in Japanese manufacturing workers.

BACKGROUND Fatigue is one of the most common symptoms encountered in medical practice. However, little is known about the causal relationship between change in lifestyle and fatigue. AIM To help prevent fatigue-related disorders, we investigated the association between changes in lifestyle and fatigue among employees. METHODS We studied data sets from the High-risk and Population Strategy for Occupational Health Promotion study for employees at 10 workplaces in Japan. The baseline survey was done in 1999 and the follow-up survey in 2003 via a questionnaire which examined lifestyle and fatigue variables using the vitality domain scale of the SF-36 Health Survey. The lifestyle factors focused on were diet, smoking and alcohol habits and working conditions. Four-year changes in lifestyle that predicted the vitality domain score in the follow-up survey were examined by analysis of covariance RESULTS Of the 6284 participants in the baseline survey, 4507 replied to the follow-up survey, of whom 3498, with a mean age of 37 (SD 18) years, returned valid responses. A low vitality score at follow-up was predicted by a change in lifestyle factors such as an increase in overtime work, change to non-sedentary work and increased frequency of eating between meals (P < 0.01, P < 0.01 and P = 0.02, respectively). CONCLUSION Fatigue in salaried workers as measured by the vitality domain of the SF-36 is predicted by an increase in overtime work, change to non-sedentary work and an increase in the frequency of eating between meals.