In a systematic review and meta-analysis of studies on laughter yoga, researchers suggest that “simulated” (nonhumorous) laughter is more effective than “spontaneous” (humorous) laughter, and that laughter-inducing therapies can improve depressive symptoms.[1] They noticed that significant medium-large effects were observed in two studies over the short term. However, researchers highlight the need to conduct rigorous trials of laughter yoga before the intervention can be considered as an evidence-based intervention to improve mental health.[2]

In a randomized, controlled clinical trial, 60 participants diagnosed with IBS and symptoms of anxiety were randomly assigned to either a laughter yoga group, an antianxiety medication group, or a symptomatic treatment (control) group.[3] Researchers found that anxiety after interventions decreased in all three groups, and especially in the yoga treatment group, but with no statistical significance between groups (p = 0.1). However, the laughter-yoga group experienced a statistically significant decrease in the severity of IBS symptoms than both the anxiety medication and control groups (p = 0.006). Authors concluded that laughter yoga is more effective than antianxiety medication in reducing the gastrointestinal symptoms of patients with IBS, and that applying laughter yoga along with standard treatments for patients with IBS might be strongly advised.[4]