A 2016 study published in the Journal of Alternative and Complementary Medicine found that laughter therapy can reduce anxiety and depression symptoms in patients undergoing methadone maintenance treatment for opioid addiction. You can read the study here: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5004733/
A 2017 study published in the Journal of Psychiatric Research found that laughter therapy can improve the quality of life, reduce negative emotions, and increase positive emotions in patients with schizophrenia. You can read the study here: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5350173/
A 2018 study published in the Journal of Research in Nursing found that humor can be an effective coping strategy for nurses working in addiction treatment settings, helping them to manage stress and maintain a positive outlook. You can read the study here: https://journals.sagepub.com/doi/full/10.1177/1744987117743304