Background: This case-control study investigated the relationship between sleep duration and quality with the occurrence of breast cancer among women, both pre- and post-menopausal, in the northwest Khyber Pakhtunkhwa (KP) region of Pakistan.
Method: This case-control research was carried in multiple tertiary care facilities. Newly diagnosed primary breast cancer patients were recruited as cases (n = 408), and 5+ years age-matched controls (n = 408) were randomly selected from the general population. Participants completed a Pittsburg sleeping quality index (PSQI) questionnaire that included questions on sleep characteristics. Statistical analysis included independent t-tests to compare mean sleep durations and quality scores between groups, and logistic regression to adjust for potential confounders.
Results: Sleep onset latency between cases and controls was not significantly associated with health outcomes, with a P-value of .142. However, sleep duration showed a significant association (P = .049). For sleep duration, the adjusted odds ratio for ≤6 h was 1.02 (95% CI: .5-2.1), while for 7-8 h the adjusted odds ratio was 1.0 (95% CI: .6-1.6). Self-reported sleep quality did not demonstrate significant associations, with the P-value for "very good" sleep quality being .561. Sleep duration of less than 6 h among women with triple-negative breast cancer (TNBC) was found to be strongly associated with a more aggressive type of breast cancer, with an adjusted odds ratio of 1.5 (95% CI: 1.02-2.3, P < .05).
Conclusion: This study does not provide evidence to support an association between sleep duration or quality and the risk of breast cancer. However, it reports a significant association, with shorter sleep durations linked to an increased risk particularly in the context of aggressive breast cancer types such as TNBC.
Keywords: breast cancer; case-control study; sleep duration; sleep quality.