Background: Very few studies have examined sleep duration in relation to cancer incidence with the exception of breast cancer.
Methods: We assessed the associations between sleep duration and incidences of total and 18 site-specific cancers in the NIH-AARP Health and Diet Study cohort, with 173,327 men and 123,858 women aged 51-72 years at baseline. Self-reported sleep duration categories were assessed via questionnaire. We used multivariable Cox proportional hazards regression to estimate hazard ratios (HR) and 95% confidence intervals (CI), using 7-8 hours/night as the reference.
Results: We observed a significantly increased risk of stomach cancer among male short sleepers (multivariable HR5-6 vs. 7-8 hours = 1.29; 95%CI: 1.05, 1.59; Ptrend = 0.03). We also observed suggestive associations in either short or long sleepers, which did not reach overall significance (Ptrend >0.05), including increased risks in male short sleepers for cancers of head and neck (HR<5vs.7-8 hours = 1.39; 95%CI:1.00-1.95), bladder (HR5-6vs.7-8 hours = 1.10; 95%CI:1.00-1.20), thyroid (HR<5 vs. 7-8 hours = 2.30; 95%CI:1.06, 5.02), Non-Hodgkin Lymphoma (NHL) (HR5-6vs.7-8 hours = 1.17; 95%CI:1.02-1.33), and myeloma (HR<5vs.7-8 hours = 2.06; 95%CI:1.20-3.51). In women, the suggestive associations include a decreased total cancer risk (HR<5vs.7-8 hours = 0.9; 95%CI:0.83-0.99) and breast cancer risk (HR<5vs.7-8 hours = 0.84; 95%CI:0.71-0.98) among short sleepers. A decreased ovarian cancer risk (HR≥ 9 vs. 7-8 hours = 0.50; 95%CI:0.26-0.97) and an increased NHL risk (HR≥ 9 vs. 7-8 hours = 1.45; 95%CI:1.00-2.11) were observed among long sleepers.
Conclusion: In an older population, we observed an increased stomach cancer risk in male short sleepers and suggestive associations with short or long sleep duration for many cancer risks in both genders.