In the 1990s, refinery workers in operator and maintenance positions transitioned to extended (12 hour) rotating shifts that alternate between days and nights every few days. Since then lean production management styles have resulted in average overtime rates of 40% at many facilities, which severely impact worker recovery time. This study aims to characterize the prevalence of chronic diseases that are associated with rotating shift work in the study population, using a self-reported health questionnaire administered to the oil sector membership of the United Steelworkers union. We explore associations between work schedules and health and quality of life outcomes. Reported work schedules, overtime estimates, and histories of shift work were used to estimate exposure. Self-reported diagnoses of cardiovascular disease, hypertension, diabetes, and gastro-intestinal illness were used to calculate disease prevalence in the study population. Job stress, quality of life, and sleep quality was also measured using validated tools, and a depression assessment was performed. Data was collected on fatigue related safety incidents.