Weight gain in relation to night work among nurses Elaine C Marqueze a,* , Lucia C Lemos a , Nilson Soares a , Geraldo Lorenzi-Filho b and Claudia R.C. Moreno a a Departamento de Saúde Ambiental, Faculdade de Saúde Pública, Universidade de São Paulo, Av. Dr. Arnaldo, 715, Zip Code 01246-904, São Paulo, SP, Brazil b Instituto do Coração - InCor - Universidade de São Paulo, Av. Dr. Enéas de Carvalho Aguiar, 44, Zip Code 05403-900, São Paulo-SP, Brazil Abstract. Objective: To investigate the relationship between working at night and increased body weight in nurs- ing. In addition, we evaluated the differences in the proportion of variables sociodemographic, work and health, according to the work shift and their association with body mass index. Methods: Based on questionnaires, we obtained data from 446 nursing professionals about aspects of their job, health and lifestyle. We performed linear and logistic regression analysis. Results: Working at night is associated with a weight gain greater than (=0.24 kg/m 2 ) working during the day (=0.15 kg/m 2 ), as well as with aging (=0.16 kg/m 2 ) and duration of working in nursing (=0.18 kg/m 2 ). Night workers have a higher educational level, have been working for more years in nurs- ing and also in the current shift, do not have diabetes and have reported longer sleep than day workers. There are also a higher number of smokers among the night workers than day workers. Logistic regression analysis also showed the more time to work in nursing and as an assistant was more likely to develop overweight/obesity. Con- clusion: Working at the night contributes to more weight gain than the day shift, aging and duration of working in nursing. Keywords: shift work, weight gain, nursing professionals, night work, body mass index. * Corresponding author. Phone + 55 11 3061-7905. E-mail: ecmarqueze@usp.br 1. Introduction Shift and night workers represent about 20% of the workforce of the European community [34] and also the United States [15]. Fischer [12] estimates that in Brazil, this percentage reaching 15% of the work- force. Schemes of work that alter the organization of work and sleep schedules of the individual can pro- duce fatigue, mental irritability, tendencies toward depression, disturbances in appetite, intestinal organs and also in sleep [14]. Night work is usually associated with reduced du- ration and quality of sleep. In recent researches an association between sleep and obesity has been ob- served [4, 7, 16, 21-22, 24-25, 30], where the low quality and short duration of sleep are closely related to weight gain. However, obesity is a multifactorial syndrome in which disorders of energy balance, resulting from temporal desynchronization with the biological tem- poral organization, may have an important and deci- sive role in its genesis. Some authors suggest that chronic desynchronization of circadian rhythms, as observed among shift workers, can affect energy me- tabolism and body weight regulation, promoting the development of obesity [10-11, 31]. Karlsson et al [19] present that not only the sleep reduction, but also its change associated with the cir- cadian desynchronization is associated with obesity. In animal models, Salgado-Delgado et al [28] found that obesity was caused by food intake during the rest Work 41 (2012) 2043-2048 DOI: 10.3233/WOR-2012-0429-2043 IOS Press 1051-9815/12/$27.50 © 2012 – IOS Press and the authors. All rights reserved 2043