Hello,
This is a very curious search wich I found on the net. According to the Cancer Treatment Centers of America, laughter therapy is a natural medicine:
What is laughter therapy?
We were born with the gift of laughter. Laughter is a natural medicine. It lifts our spirits and makes us feel happy. Laughter is a contagious emotion. It can bring people together. It can help us feel more alive and empowered.
Laughter therapy, also called humor therapy, is the use of humor to promote overall health and wellness. It aims to use the natural physiological process of laughter to help relieve physical or emotional stresses or discomfort.