Sleep Duration, Chronotype, and Insomnia and the Risk of Lung Cancer: United Kingdom Biobank Cohort

Background: Relationships between sleep duration, chronotype, insomnia, and lung cancer risk have not been comprehensively examined. Interrelations between sleep traits on the risk of lung cancer have not been assessed. We aimed to examine sleep traits with lung cancer risk. Methods: Participants were recruited between 2006 and 2010 and followed through November 30, 2020. We included 382,966 participants (3,664 incident lung cancer) in analysis. Cox proportional hazards models estimated HRs and 95% confidence intervals (CI) for associations between sleep duration, chronotype, and insomnia symptoms and lung cancer risk. Joint effects analyses were examined between sleep duration and three traits (chronotype, insomnia, and daytime napping). Nonlinear associations between sleep duration and lung cancer risk were assessed in restricted cubic spline analysis. Results: Longer sleep (>8 hours) was positively associated with lung cancer risk compared with normal sleep duration (7-8 hours; HR = 1.22; 95% CI, 1.10-1.36). Frequent insomnia symptoms increased the risk of lung cancer compared with never/rarely experiencing symptoms (HR = 1.16; 95% CI, 1.05-1.28). Joint effects between sleep duration and chronotype, and sleep duration and insomnia symptoms were observed. In analysis excluding participants reporting shift work at baseline, evening chronotypes ("slight,""definite") were at a greater risk of lung cancer compared with definite morning chronotype (HR = 1.17; 95% CI, 1.06-1.28 and HR = 1.37; 95% CI, 1.21-1.54, respectively). Conclusions: Sleep traits such as long sleep duration, frequent insomnia symptoms, and definite evening chronotype may be risk factors for lung cancer. Joint effects should be further investigated.