Sleep traits and breast cancer risk - a two-sample Mendelian randomization study

Sep 21, 2026

Uploaded by Liam

Breast cancer remains the leading cause of cancer incidence and mortality among women, and sleep behaviors may influence tumor onset and progression. This study evaluates seven sleep traits using a two-sample Mendelian randomization framework, drawing genetic instruments from UK Biobank and 23andMe and disease summary data from the Breast Cancer Association Consortium. Chronotype effects were observed across overall and subtype analyses, with several sleep traits showing protective associations against breast cancer risk.

LanguageEnglish

CategoryResearch & Report

FormatPDF

Pages9

Reading Time23 min

AccessFree to download

Introduction

Sleep-related risk context

Epidemiology and lifestyle links

Sleep disorders prevalence

Chronotype and circadian factors

Genetic and environmental determinants

[www. nature.com/scientificreports](www. nature.com/scientificreports) OPEN Sleep traits and breast cancer risk: a two‑sample Mendelian randomization study Jing Feng1, Yixue Wen1, Zhen Zhang1* & Ye Zhang2* Globally, breast cancer continues to be the leading cause of cancer‑related incidence and mortality among females. Research has shown that sleep patterns significantly influence tumor onset and progression. In this research, the association was examined through the application of a two‑sample Mendelian randomization (MR) approach. For the analysis of seven sleep patterns, genetic tools were sourced from both the UK Biobank and 23andMe, including morning/evening person (chronotype) n = 177,604, morning person (chronotype) n = 248,094, daytime dozing/sleepiness n = 193,472, getting up in the morning n = 193,717, and sleeplessness n = 193,987; sleep duration n = 192,810; and nap during the day n = 166,853. The Breast Cancer Association Consortium (BCAC) supplied genome‑wide association studies (GWAS) data, including 133,384 breast cancer cases and 113,789 controls, alongside subtype‑specific data with 106,278 cases and 91,477 controls. We discovered that chronotype encompasses both morning and evening types contributes to the risk of overall breast cancer. While daytime dozing and morning person (chronotype) are linked to a lower risk of breast cancer in general, In subtype‑specific analyses, morning person (chronotype) was negatively associated with luminal B, HER2‑negative‑like, and daytime dozing was negatively correlated with luminalA‑like, luminal B‑like, and HER2‑enriched‑like. The study corroborates that chronotype is a danger element for breast cancer, aligning with previous observational findings. The association between being a morning person (chronotype) or having daytime dozing and a decreased risk of breast cancer underscores the significance of sleep patterns in formulating strategies for cancer prevention. Keywords Sleep traits, Chronotype, Daytime dozing, Breast cancer, Mendelian randomization Abbreviations MR Mendelian randomization GWAS Genome-wide association studies BCAC Breast Cancer Association Consortium SNPs Single nucleotide polymorphisms IVs Instrumental variables LD Linkage disequilibrium IVW Inverse Variance Weighted GRS Genotyping and weighted genetic risk score Across the globe, breast cancer emerges as the primary malignancy affecting females, holding the position asthe foremost contributor to oncological fatalities within this population, thus severely impacting the health and longevity of women1. The latest 2020 statistics estimate that approximately 2.3 million individuals were diagnosed with breast cancer, resulting in approximately 685,000 fatalities. Over half of these diagnoses and two-thirds of the related deaths are reported in the less developed regions, with an anticipated surge in cases in areas undergoing economic transformation1,2. Global research efforts have sought to delineate the etiology of breast cancer, revealing it to be a multifaceted disease influenced by genetic factors, lifestyle, environmental exposures, and their interplay3. A myriad of lifestyle factors, including but not limited to body composition, obesity, physical activity levels, alcohol intake, smoking habits, dietary patterns, and vitamin intake, have been definitively linked to the risk and advancement of breast cancer4–6. In recent years, scientific inquiry has increasingly concentrated 1Department of Breast Center, Mianyang Central Hospital, School of Medicine, University of Electronic Science and Technology of China, Mianyang, Sichuan, People’s Republic of China. 2Department of Neurosurgery, Mianyang Central Hospital, School of Medicine, University of Electronic Science and Technology of China, Mianyang, Sichuan, People’s Republic of China.*[email: jiangzhangtong@sina.com](email: jiangzhangtong@sina.com); [zhangye6660@163.com](zhangye6660@163.com) [www. nature.com/scientific

FAQs

Which sleep traits were evaluated in the study?

The study analyzed seven sleep patterns, including chronotype (morning/evening), morning person, daytime dozing/sleepiness, getting up in the morning, sleeplessness, sleep duration, and day naps.

What data sources were used for the Mendelian randomization analysis?

Genetic instruments for sleep traits came from UK Biobank and 23andMe, while breast cancer outcome data were provided by the Breast Cancer Association Consortium, including overall and subtype-specific GWAS results.

What relationship did the study find between chronotype and breast cancer risk?

Chronotype, encompassing both morning and evening types, was associated with overall breast cancer risk. Some sleep-related traits, such as morning person and daytime dozing, were linked to a decreased risk overall and in several subtype-specific results.

Sep 21, 2026

Uploaded by Liam

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