Doses of exposure to night shift work and nutritional status among nursing workers

Introduction: Exposure to night work (NW) has been identified as a possible risk factor for body weight gain. Recent studies highlight the need to assess the intensity and frequency of exposure to night work (i.e., years of exposure and number of nights worked). Objectives: To investigate the relationships between the dose of exposure to night work (years working nights and number of nights worked) and nutritional status (excess weight, waist circumference), abdominal obesity, and body mass index in nursing professionals. Methods: Data were analyzed on night workers (n = 529) from a public hospital in Rio de Janeiro, Brazil. Descriptive analyses were conducted and crude and adjusted regression models were constructed to test the associations between exposures and outcomes. Analyses were performed using R, version 2.15. Results: Working at night for 10 years or more was associated with excess weight (odds ratio [OR] = 1.76; 95% confidence interval [95%CI] 1.14-2.72), with abdominal obesity (OR = 1.76; 95%CI 1.14-2.74), with increased body mass index (ß = 2.28; 95%CI 1.31-3.26), and with increased waist circumference (ß = 4.63; 95%CI 2.38-6.88), when compared with exposure to NW for less than 10 years, after adjusting for covariates. The current dose of night work only exhibited a borderline association between > 5 nights/fortnight and abdominal obesity (OR = 1.55; 95%CI 1.01-2.01). Conclusions: Detailing night work exposure can contribute data to support strategies for organizing working hours that consider the possibility of limiting the time exposed to night work.