The effects of group-based Laughter Yoga interventions on mental health in adults: A systematic review.

Introduction Laughter Yoga is claimed to promote mental health and is increasingly popular worldwide. Despite its popularity, there has been no systematic review of Laughter Yoga intervention studies and thus evidence of its effects on mental health is unclear. Aim This review aimed to critically evaluate the effects of group-based Laughter Yoga on improving mental health in adults. Method We conducted a systematic review of experimental studies (published from 1995 to 2017). Study quality was assessed, the effect sizes for individual mental health outcomes were calculated and all reviewed studies were narratively synthesized. Results Six experimental studies with inconsistent results were included in this review. The most promising effect of Laughter Yoga is the improvement of depressive symptoms, indicating significant medium-large effect sizes in two studies over the short term. The overall level of evidence was weak due to poor study quality and risks of bias. Discussion Laughter Yoga shows potential, but currently there is insufficient evidence to support its effectiveness in improving mental health when compared to other group-based interventions. Implications for practice This review highlights the need to conduct rigorous trials of laughter yoga before the intervention can be considered as an evidence-based intervention to improve mental health.