Sedentary time by occupation in a nationally representative Japanese population: a descriptive study using the National Health and nutrition survey

Objectives: Prolonged sitting time is gradually being recognized as detrimental to health. As technological advances have made workplaces increasingly sedentary, describing sitting time by occupation is useful for identifying at-risk groups and promoting occupational health. This study aimed to elucidate the differences in sedentary time according to occupation using a nationally representative sample. Methods: Self-reported total sedentary (sitting or lying down during waking hours) time was obtained from the 2013 National Health and Nutrition Survey. Occupations were classified as professionals, managers, clerks, sales, service, protective services, agricultural/forestry/fishery workers, transport/machine operators, manufacturing/construction/cleaning laborers, homemakers, and unemployed individuals. Sedentary time by occupation was compared using an analysis of covariance adjusted for age and sex. Results: A total of 4071 workers aged 20–64 years were analyzed. Age-adjusted sedentary time was longer in men than in women. The age-adjusted sedentary time among different occupations ranged from 280 to 499 min/day. The longest age-adjusted sedentary time was observed among clerks (499 min/day), followed by managers (437 min/day). In contrast, the shortest sedentary time was observed among agricultural/forestry/fishery workers (280 min/day). Clerks and managers had longer sedentary time on weekdays than on days off, whereas other occupations, including homemakers, did not. Conclusions: Sedentary time differed substantially among occupations, with a variation of approximately 3.5 h per day. Prolonged sedentary time, a known health risk, may represent a substantial occupational exposure, particularly among clerical workers. Occupational health staff should monitor workers’ sedentary time to promote better occupational health outcomes.