Abstract
Sleep duration is a novel and potentially modifiable risk factor for cancer. We evaluated the association of self-reported sleep duration and daytime napping with odds of colorectal and gastric cancer. We included 2008 incident colorectal cancer cases, 542 gastric cancer cases and 3622 frequency-matched population controls, recruited in the MCC-Spain case–control study (2008–2013). Sleep information, socio-demographic and lifestyle characteristics were obtained through personal interviews. Multivariable adjusted logistic regression models were used to estimate odds ratios (OR) with 95% confidence intervals (CI) for cancer, across categories of sleep duration (≤ 5, 6, 7, 8, ≥ 9 hours/day), daytime napping frequency (naps/week) and duration (minutes/nap). Compared to 7 hours of sleep, long sleep was associated with increased odds of colorectal (OR≥9 hours: 1.59; 95%CI 1.30–1.94) and gastric cancer (OR≥9 hours: 1.95; 1.37–2.76); short sleep was associated with increased odds of gastric cancer (OR≤5 hours: 1.32; 0.93–1.88). Frequent and long daytime naps increased the odds of colorectal (OR6–7 naps/week, ≥30 min: 1.32; 1.14–1.54) and gastric cancer (OR6–7 naps/week, ≥30 min: 1.56; 1.21–2.02). Effects of short sleep and frequent long naps were stronger among participants with night shift-work history. Sleep and circadian disruption may jointly play a role in the etiology of colorectal and gastric cancer.
Highlights
Sleep duration is a novel and potentially modifiable risk factor for cancer
After the exclusion of retired participants and participants with more than 6 months between the date of diagnosis and interview most results were unchanged or became stronger. In this large case–control study we found that participants with longer sleep duration (8 hours and ≥ 9 hours) had significantly increased odds of colorectal and gastric cancer, compared to those with 7 hours of sleep
Frequent (6–7 days/week) long (> 60 min) naps were associated with increased odds of colorectal and gastric cancer
Summary
We evaluated the association of self-reported sleep duration and daytime napping with odds of colorectal and gastric cancer. Long sleep duration has been associated with an increased risk of colorectal cancer in two prospective cohorts of health professionals, especially among individuals who were overweight or snored regularly[16]. Only one study, a prospective cohort of older adults, has reported an increased risk for gastric cancer associated with short sleep[18]. To our knowledge, evaluated daytime napping as a risk factor for colorectal and gastric cancer. Our aim in the present study was to evaluate habitual sleep duration and daytime napping in relation to colorectal and gastric cancer adjusting for potential confounders and other sleep characteristics in a large population based case–control study. We conducted stratified analyses by night shift work history to evaluate potential joint effects of sleep and circadian disruption in relation to gastrointestinal cancer risk
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