Effectiveness of Moderate-Intensity Exercise Interventions on Sleep Quality in Adults with Insomnia (20–60 Years): A Systematic Review and Meta-analysis

Background: Insomnia is a prevalent sleep disorder among working-age adults and is associated with adverse physical, psychological, and socioeconomic outcomes. Exercise is recommended as a non-pharmacological therapy; however, evidence focusing specifically on moderate-intensity exercise aligned with World Health Organization (WHO) guidelines remains unclear. Objective: To systematically review and quantitatively synthesize evidence on the effectiveness of moderate-intensity exercise interventions on sleep quality, measured by the Pittsburgh Sleep Quality Index (PSQI), in adults aged 20–60 years with insomnia. Methods: A systematic review and meta-analysis were conducted in accordance with PRISMA guidelines. Electronic databases (PubMed, Scopus, Web of Science, and Cochrane Library) were searched from inception to December 2025. Eligible studies included adults with insomnia receiving moderate-intensity exercise interventions consistent with WHO recommendations and reporting pre- and post-intervention PSQI scores. Random-effects meta-analysis was performed using standardized mean differences (Hedges’ g). Results: A total of 12 randomized and quasi-randomized controlled trials involving 1,046 participants met the inclusion criteria. Meta-analysis demonstrated a statistically significant improvement in global PSQI scores following moderate exercise interventions (pooled Hedges’ g = −0.65; 95% CI −0.88 to −0.42; p < 0.001), indicating a moderate effect size. Heterogeneity was moderate (I² = 52%). Conclusion: Moderate-intensity exercise interventions consistent with WHO guidelines significantly improve sleep quality in adults aged 20–60 years with insomnia. These findings support moderate exercise as an effective first-line non-pharmacological treatment for insomnia.