Social Jetlag Among Night Workers is Negatively Associated with the Frequency of Moderate or Vigorous Physical Activity and with Energy Expenditure Related to Physical Activity.

Research paper by Mariana Silva MS Alves, Raphael Zardini RZ Andrade, Graciele Cristina GC Silva, Maria Carliana MC Mota, Sabrina Gonçalves SG Resende, Kely Raspante KR Teixeira, Bruna Fernandes BF Gonçalves, Cibele Aparecida CA Crispim

Indexed on: 23 Dec '16Published on: 23 Dec '16Published in: Journal of biological rhythms


This cross-sectional study analyzed the association between physical activity (PA) and social jetlag (SJL) among shift workers. We evaluated 423 employees, aged between 18 and 60 years, who worked in a poultry-processing company in Brazil. Physical activity levels (PAL) were determined by the short form of the International Physical Activity Questionnaire (IPAQ-SF). SJL was calculated as the absolute difference between the time of mid-sleep on work and free days. The percentage of workers insufficiently active was high on all shifts, with no significant differences between the 3 shifts. The amount of time spent in sedentary behavior on workdays did not differ between shifts. Among night-shift workers, negative associations were observed between SJL and 1) the duration and weekly energy expenditure while walking; 2) the frequency of moderate and vigorous PA; and 3) the total energy expenditure related to PA. Even though PAL did not differ among workers on different shifts, we found a high prevalence of subjects who were insufficiently active or too sedentary among all groups. Also, SJL was negatively associated with PA in night-shift workers. These results suggest that PA should be encouraged among shift workers and that SJL may be an important factor in reducing PA in this cohort.