Long working hours, occupational health and the changing nature of work organization.

BACKGROUND The impact of long working hours on health has been of major concern since the late 19th Century. Working hours are again increasing in the US. METHODS An overview of historical, sociological, and health-related research presented at an international conference on long working hours is discussed as an introduction to a special section in this issue. RESULTS Research indicates that long working hours are polarizing along class lines with professionals working regular though longer hours and less well-educated workers having fewer though more irregular hours. Extended and irregular hours are associated with acute reactions such as stress and fatigue, adverse health behavior such as smoking, and chronic outcomes such as cardiovascular and musculoskeletal disorders. CONCLUSIONS Improved methodologies are needed to track exposure to long working hours and irregular shifts longitudinally. Research should focus on the adverse impact that sleep-deprived and stressed workers may have on the health of the public they serve. A variety of protective efforts should be undertaken and evaluated.