The effects of shift work on free-living physical activity and sedentary behavior

Objective: Although occupation may influence physical activity and shift work schedule may influence cardiovascular disease risk factors, our understanding of the effects of shift work schedule on overall physical activity behavior and sedentary behavior is limited.

Methods: Data from the 2005-2006 National Health and Nutrition Examination Survey were used. Shift work schedule was defined as regular daytime shift, evening, night, rotating or another schedule. Physical activity and sedentary behavior were assessed via accelerometry. 1536 adult participants (≥20years) indicated they currently work and provided data on all study variables.

Results: After adjustments, and compared to adults working a regular daytime shift, those working an evening (RR=0.41, p=0.001) and night (RR=0.30, p=0.001) shift, respectively, engaged in 59% and 70% less sustained (bouts) moderate-to-vigorous physical activity, but no differences occurred for overall moderate-to-vigorous physical activity. After adjustments, and compared to those working a regular daytime shift, those working a rotating shift engaged in more light-intensity physical activity (overall: β=26.3min/day; p=0.03; bouts: β=37.5, p=0.01) and less sedentary behavior (β=-28.5min/day, p=0.01).

Conclusions: Shift work schedule differentially influences physical activity and sedentary behavior. Physical activity and sedentary intervention strategies may need to be tailored based on shift work schedule.