Association between probiotic intervention and sleep quality in the general adult population: a systematic review and meta-analysis

Abstract

Background: The discovery of the microbiota-gut-brain axis provides a theoretical basis for using probiotic supplementation to improve sleep health. This meta-analysis systematically evaluated the efficacy of probiotics in adults, including both healthy individuals and those with poor sleep quality.

Methods: Eight public databases were searched to identify relevant randomized controlled trials (RCTs) published before December 2025 to be included in this review. Data from the included studies were extracted, and their risk of bias was assessed. Meta-analysis, sensitivity analysis, and publication bias assessment were conducted using Review Manager 5.4.1.

Results: A total of 13 studies involving 890 participants reported outcomes using the Pittsburgh Sleep Quality Index (PSQI). The meta-analysis revealed that probiotic supplementation significantly reduced PSQI scores compared to the control group (mean difference [MD] = -0.59, 95% confidence interval [CI]: -0.83 to -0.35, p < 0.001), indicating moderate heterogeneity (I ² = 46%). For the Insomnia Severity Index (ISI), the probiotic group also showed significantly lower scores (MD = -0.86, 95% CI: -1.60 to -0.12, p = 0.02; I ² = 26%). In contrast, no significant changes were observed in the Epworth Sleepiness Scale (ESS) scores or serum cortisol levels.

Conclusion: Probiotic supplementation was associated with a modest but statistically significant improvement in sleep quality among adults, regardless of their baseline sleep status (ranging from healthy to suboptimal), as measured by PSQI and ISI scores.

Systematic review registration: https://www.crd.york.ac.uk/PROSPERO/view/CRD420251237016, PROSPERO (CRD420251237016).

Keywords: adult; meta-analysis; probiotics; sleep quality; systematic review.