Longitudinal sleep duration and subsequent development of cancer in the Japanese population

Evidence of the association between sleep duration and subsequent cancer development is inconsistent. The aim of this study was to evaluate the association between sleep duration and any type of cancer incidences in the Japanese population. A retrospective longitudinal study was conducted from 2005 to 2018 at St. Luke's International Hospital, Tokyo, Japan. All participants were ≥50 years old and underwent health check-ups at the Center for Preventive medicine at the hospital. Our outcome was the development of any type of cancer during follow-up. The outcomes were evaluated across the sleep duration categories with a longitudinal analysis adjusted for potential confounders. A total of 24,873 participants were included in this study; the mean age was 59.1 years (standard deviation: 7.2) and 13,258 (53.3%) were male. During the median follow-up of 1,841 days (interquartile range: 821-3,246); 2,544 (10.2%) developed a type of cancer. After adjusting for potential confounders, the development of any type of cancer did not vary across the sleep duration categories compared to the reference group (6-7 hours) (adjusted ORs were from 0.95 to 1.15, all were statistically insignificant). In terms of each type of cancer, sleep duration was associated with malignant neoplasms of digestive organs associated with a U shape and long sleep duration was associated with a higher incidence of malignant neoplasms of lymphoid, hematopoietic, and related tissues (OR 15.9, 95%CI: 1.61-156) among females. According to our longitudinal study, there was no clear association between sleep duration and subsequent development of any type of cancer. However, sleep duration was associated with certain types of cancer such as that of digestive organs, lymphoid, hematopoietic, and related tissues in females, and genital organs in males.