The associations between sleep-related factors and bladder cancer: A cross-sectional study in the UK Biobank

Background: The aim of this study was to explore the associations between various sleep-related factors and bladder cancer risk. These factors included sleep duration, ease of getting up in the morning, daytime napping, insomnia, snoring, daytime dozing, and chronotype. Methods: This study is cross-sectional, and the data were obtained from UK Biobank. A total of 502,492 participants at recruitment (2006-2010) were included. Multiple imputation was performed to address missing data. Univariable logistic regression models adjusted for covariates were used to examine associations between sleep-related factors and bladder cancer, and if there were factors associated with bladder cancer, a multivariable logistic regression would be conducted to evaluate potential mutual confounding between these factors. A stratified analysis was conducted to assess if the associations would be applicable for both genders. A P-value below 0.05 was considered to indicate statistical significance. Results: There were 1414 (0.28 %) participants had been diagnosed with bladder cancer at recruitment. After adjusting for all covariables, daytime napping and insomnia with a frequency of "usually" were associated with a higher prevalence of bladder cancer. The multivariable logistic regression suggested that daytime napping and insomnia remained independently associated with bladder cancer and there was no significant evidence of confounding effects. Stratified analyses indicated a potential trend suggesting that frequent daytime napping or insomnia may be associated with an increased risk of bladder cancer in both genders. Conclusion: Daytime napping and insomnia are associated with an increased risk of bladder cancer. Future research is needed to explore the underlying mechanisms and establish causative relationships.