Associação entre jetlag social e padrão de atividade física em trabalhadores em turnos fixos

Abstract

Social jetlag (SJL) measures the discrepancy between sleep time on workdays and days off, and if a discrepancy becomes chronic, can have harmful health consequences. Although some studies suggest that shift workers are mostly sedentary, little is known about the associations between physical activity patterns and SJL among these workers. The aim of this study was to analyze the association between physical activity and social jetlag (SJL) among workers who were performing different shift work schedules. Four hundred and twenty-three shift workers (122 early-morning shift, 133 day shift and 168 night shift) employed at a Brazilian poultry processing company participated in the study. PAL was assessed using the short version of the International Physical Activity Questionnaire (IPAQ-SF). Demographics, work hours, sleep patterns, SJL and chronotypes were identified from a questionnaire. Measurements of weight, height and waist circumference (WC) were also obtained. The percentage of workers inactive was high on all shifts with no significant differences among the three shifts (p= 0.69). The amount of time spent in sedentary behaviors on workdays, as well as the weekly energy expenditure did not differ between shifts (p = 0.10 p = 0.8, respectively). The results of the linear regression analysis indicated a negative association between SJL and the frequency of moderate (β= -0.14, p= 0.04) and vigorous (β= -0.17, p= 0.03) physical activity among night shift workers. In the same individuals, it was also found a negative association between SJL and the energy expenditure (MET) for vigorous physical activity (β= -0.15, p= 0.04). We concluded that SJL is negatively associated to the frequency of moderate and vigorous physical activities, as well as to the energy expenditure for vigorous physical activity among night-shift workers. Despite the PAL did not differ among workers of different shifts, it was found a high prevalence of individuals who are insufficiently active and engage in sedentary behavior among all groups of workers. These results suggest that physical activity should be encouraged among shift workers, and that SJL may be an important complicator of physical activity in these individuals.