# Sleep Traits to the Risk of Breast Cancer Disease Incidence, Adverse Progression and Mortality: Evidence From a Global Systematic Review and Meta-Analysis

## TL;DR

Poor sleep quality increases the risk of breast cancer and its progression, while long sleep duration may raise mortality risk.

## Contribution

This study provides a global meta-analysis linking sleep traits to breast cancer outcomes.

## Key findings

- Low sleep quality significantly increases breast cancer incidence, progression, and mortality risks.
- Sleep duration longer than 9 hours is associated with higher breast cancer-specific mortality.
- Sleep traits mainly affect disease progression rather than initial cancer risk.

## Abstract

This study aimed to identify the effect of sleep traits on the risk of breast cancer incidence and adverse progression and mortality.

Cohort studies measuring the relationship between sleep traits (including sleep quality and sleep duration) and breast cancer risk were eligible for inclusion. We searched the Web of Science, PubMed, EMBASE and Cochrane library databases for studies published between 2014 and 2024. Maximum covariate-adjusted odds ratio (OR) was combined. A fixed or a randomized effect model was applied according to the heterogeneity.

34 studies met the inclusion and exclusion criteria. Low quality sleep significantly increased the risk of incidence (OR:1.09, 95%CI:1.05–1.13), adverse progression (OR:1.55,95%CI:1.51–1.59), and specific mortality (OR:1.54, 95%CI:1.50–1.58) of breast cancer. Sleep duration >9 h had a poor effect on breast cancer-specific mortality (OR:1.45,95%CI:1.02–2.04).

The available evidence points to sleep traits as primarily influencing progression in breast cancer patients and having a relatively small effect on breast cancer incidence. Prolonged sleep may lead to breast cancer-specific mortality, but more research is needed in the future to continue to explore the impact of sleep duration and breast cancer risk.