The Impact of Sleeping Duration on the Risk of Breast Cancer: A systematic Review and meta-analysis of population-based cohort studies

Keywords: Breast cancer; sleep duration and breast cancer; systematic review; metaanalysis of breast cancer studies; population-based cohort studies.

Abstract

The impact of different sleeping categories on the risk of breast cancer has remained debatable. This paper sought to systematically synthesise the available literature on this relationship from population-based cohort studies using meta-analytic procedures. Studies about sleep duration and breast cancer were identified from the Cochrane Library database, EMBASE and PubMed databases for papers published up to February 2019.

Identified studies were analysed for quality using the Newcastle-Ottawa Scale. Effect sizes were visualised using funnel plots. Study heterogeneity was quantified using I^2 and visualised using Baujat plots. Publication prejudice was evaluated using Eggers regression model, with visualisations using funnel plots. Eight cohort studies met the inclusion criteria. Random-effects model revealed nonstatistically significant evidence of an association between short or long sleep and breast cancer Odds Ratio (OR) = 0.90;(95% CI 0.79–1.02) and OR=0.95 (0.88–1.02)respectively. There was moderate to high heterogeneity I^2 (95% CI)=74.40% (48.20– 87.40%) among studies examining short sleep and breast cancer, and low to moderate heterogeneity in studies for long sleep and breast cancer I^2 (95% CI)=3.0% (0.00– 68.60%).

This study found non-substantial evidence of associations between sleeping periods and breast cancer in women. Studies employing novel sleep-measurement methodologies should be carried out to examine the underlying relationship.

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