OBJECTIVE To study shift-related differences (day shift vs. night shift) in health and quality of life in nursing staff in hospitals in the Catalan public health system. METHODS We performed a cross-sectional multicenter study in a sample of 476 nursing staff in the wards and special services of five Catalan public hospitals working for at least 6 consecutive months on the day shift or night shift. The nurses completed a validated, self-administered questionnaire on quality of life (M. Ruiz and E. Baca) and another questionnaire on health-related aspects such as sleep, working conditions, and demographic variables. RESULTS Nurses working on the night shift showed a higher prevalence of appetite disturbance (45.2% vs 34.4%; p=0.01) and varicose veins (46.6% vs 36.4%; p=0.008). Sleeping disorders were also more frequent on the night shift, including insomnia and sleep fragmentation, with no differences in those who slept during the day (22.3%vs 33.7% ) or night (17.6% vs 30%) with respect to the day shift (12.2% vs 22.6%). Multivariate analysis of the results of the quality of life questionnaire revealed the night shift to be associated with the dimensions of social support (OR: 1.17; 95% CI, 1.01-3.01), physical/psychological well-being (OR: 1.04; 95% CI, 1.004-1.07) and leisure time (OR: 1.07; 95% CI, 1.003-1.1), although the overall score was similar. CONCLUSIONS The night shift is associated a higher incidence of varicose veins, appetite disturbance and sleep disorders, as well as alterations related to social support, leisure time, and physical and physiological well-being.