This meta-analysis aimed to evaluate the efficacy of laughter intervention in alleviating stress among adults through randomized controlled trials (RCTs) and explore sources of heterogeneity. Following PRISMA guidelines, 15 RCTs (1,344 participants) were identified via searches in PubMed, PsycINFO, Web of Science, CNKI, and Wanfang Data up to June 2025. Study selection, quality assessment (Cochrane Risk of Bias tool), and data extraction were conducted independently by two reviewers. Meta-analysis was performed using RevMan 5.4 and Stata17.0, with stress outcomes pooled via random-effects models. Sensitivity and subgroup analyses assessed robustness and heterogeneity. Interventions included laughter yoga, simulated laughter sessions, and comedy-based therapies, delivered either online or in person, over durations ranging from 1 to 16 weeks. Laughter intervention significantly reduced stress (SMD = − 1.41, 95% CI: −2.04, − 0.78; p < 0.001), although high heterogeneity was observed (I² = 95.8%). Subgroup analyses confirmed consistent benefits across clinical patients, nurses, nursing students, and mothers of NICU children. Sensitivity analyses supported result stability (p < 0.001). The methodological quality of included studies was variable, with most showing some concerns regarding allocation concealment and blinding. Based on currently available RCT evidence, laughter intervention appears to be beneficial for reducing stress in diverse adult populations. However, the finding is tempered by high statistical heterogeneity and variable methodological quality across studies. Despite a large aggregate effect size, high heterogeneity limits the precision of the estimate. While promising, these results should be interpreted cautiously. Future research should prioritize multi-center designs, standardized outcome measures, and integration of objective biomarkers (e.g., cortisol) to strengthen evidence. Methodological improvements in RCT design and cultural adaptations are critical for clinical applicability.
Li et al. (Sat,) studied this question.