Laughter Is The Best Medicine, from Helpguide.org, a non-profit organization dedicated to helping caregivers. Explains why humor literally is the best medicine:
“Laughter activates the chemistry of the will to live and increases our capacity to fight disease. Laughing relaxes the body and reduces problems associated with high blood pressure, strokes, arthritis, and ulcers. The sound of roaring laughter is far more contagious than any cough, sniffle, or sneeze. It can be a domino effect of joy and amusement!
And the good feeling that we get when we laugh can remain with us as an internal experience even after the laughter subsides.”