Sleep duration and risk of cancer in the Mexican American Mano-a-Mano Cohort

Background: To date, no study has investigated the association of sleep duration with cancer risk in Mexican Americans. Analysis: Using data from the Mano-A-Mano Mexican American Cohort study, we analyzed the relationship between sleep duration and overall cancer risk among Mexican Americans. Results: Of 10,802 subjects included in this study, 429 developed cancer during follow-up. Compared with study participants sleeping 8-9 hours per night, those sleeping less than 6 hours per night had significantly increased risk of overall cancer in both univariate and multivariate Cox regression analyses. After adjusting for social-demographic and lifestyle variables, sleeping less than 6 hours per night was associated with a 1.37-fold increased risk of overall cancer (hazard ratio = 1.37, 95% confidence interval: 1.01-1.97). In breast cancer alone, sleeping less than 6 hours per night was associated with a 1.86-fold increased risk of breast cancer (hazard ratio = 1.86, 95% confidence interval: 1.01-3.45) after adjustment for birthplace and language acculturation. In further stratified analysis, significant associations between sleeping less than 6 hours per night and overall cancer risk were evident among overweight participants, former drinkers, those with medium or high levels of physical activity, those married or living together, and those who had less than 2 hours of sitting time per day. In addition, increased cancer risk associated with long sleep duration (at least 9 hours per night) was observed among overweight participants and those with medium or high levels of physical activity. Conclusion: Our results provide evidence to link sleep duration with cancer risk among Mexican Americans.