Causal Associations Between Sleep Traits and Polycystic Ovary Syndrome: A Univariable, Bidirectional, and Multivariable Mendelian Randomization Study

Mar 9, 2026The journal of obstetrics and gynaecology research

Possible two-way links between sleep patterns and polycystic ovary syndrome using genetic analysis

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Abstract

Genetically predicted sleeplessness/insomnia is associated with an increased risk of , with an odds ratio of 1.67.

A strong association exists between sleeplessness/insomnia and an increased risk of polycystic ovary syndrome (PCOS).
Sleep apnea syndrome showed a weaker association with PCOS, which diminished after adjusting for factors like body fat and insulin resistance.
No evidence indicates that PCOS causes changes in sleep traits.
Results from various sensitivity analyses support the robustness of these findings.

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BACKGROUND: Observational studies have reported associations between various sleep traits and (PCOS); however, it remains unclear whether these relationships are causal or driven by confounding factors. This study aimed to clarify the direction and magnitude of potential causal effects between eight self-reported sleep characteristics and PCOS risk using a bidirectional and multivariable (MR) framework.

METHODS: Genome-wide association study (GWAS) summary statistics for eight sleep traits (sleeplessness/insomnia, sleep duration, snoring, daytime dozing, chronotype, getting up in the morning, daytime napping, and sleep apnea syndrome) and PCOS were analyzed. Univariable MR analyses were conducted using inverse-variance weighted (IVW) meta-analysis as the primary method, supplemented by weighted median and MR-Egger regression. Sensitivity analyses included Cochran's Q test, the MR-Egger intercept, MR-PRESSO, and leave-one-out analyses. Multivariable MR analyses were further performed with adjustment for adiposity and insulin resistance.

RESULTS: Genetically predicted sleeplessness/insomnia was associated with an increased risk of PCOS (IVW OR = 1.67, 95% CI = 1.24-2.27, p = 8.6 × 10). Sleep apnea syndrome was also associated with PCOS in univariable analyses (IVW OR = 1.07, 95% CI = 1.03-1.11, p = 1.3 × 10); however, this association was attenuated after multivariable adjustment (p = 0.20). No evidence of reverse causation from PCOS to sleep traits was observed. The results were consistent across sensitivity analyses, with no evidence of horizontal pleiotropy. -4 -3

CONCLUSION: Our MR analyses support a potential causal role of sleeplessness/insomnia in increasing the risk of PCOS, whereas the association with sleep apnea syndrome may be mediated by adiposity or other confounding factors. These findings highlight the importance of sleep management in strategies for the prevention of PCOS.

Key numbers

1.67

Increase in risk

Odds Ratio for sleeplessness/insomnia associated with risk

1.07

Association with sleep apnea syndrome

Odds Ratio for sleep apnea syndrome associated with risk

254618

Sample size for GWAS

Total participants in the GWAS analysis

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Causal Associations Between Sleep Traits and Polycystic Ovary Syndrome: A Univariable, Bidirectional, and Multivariable Mendelian Randomization Study

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