Background and Objectives:Lung cancer is the most common cancer and cancer related cause of death worldwide. However, the association between sleep duration and incident lung cancer has not been investigated in a prospective cohort study. Methods:We prospectively examined the association between sleep duration and incident lung cancer in a cohort of 21,026 United States (US) male physicians. Self-reported sleep duration was ascertained during 2002 annual follow-up questionnaire. Incident lung cancer was ascertained through yearly follow-up questionnaires. Cox regression was used to estimate relative risk of incident lung cancer. Results:hTe average age at baseline was 68.3±8.8 yr. During a mean follow up of 7.5 (±2.2) yr, 150 cases of lung cancer occurred. Using 7 h of sleep as the reference group, multivariable adjusted hazard ratios (95%CI) for lung cancer were 1.18 (0.77-1.82), 1.0 (ref), and 0.97 (0.67-1.41) from lowest to the highest category of sleep duration (P for quadratic trend 0.697), respectively. In a secondary analysis, smoking status did not modify the sleep duration-lung cancer association (P=0.78). hTere was no evidence for an interaction between sleep duration and sleep apnea on the risk of lung cancer either (P=0.65). Conclusions:Our data failed to show a higher risk of lung cancer in association with altered sleep duration among US male physicians.