People who laugh a lot are much healthier than those who don't.
Dr. Lee Berk at the Loma Linda School of Public Health in California found that laughing lowers levels of stress hormones, and strengthens the immune system.
Laughter increases levels of a hormone called beta-endorphines (which elevates mood state) by 27% and increases human growth hormone by 87%. Human growth hormone (HGH) is used to treat patients with hormone deficiencies and has been shown to improve the immune system, bone and muscle mass, and reduces body fat. This is the same hormone that athletes use to improve their athletic performance in their sports.
Laughter also has been shown to reduce levels of three stress hormones: cortisol, dopac, and epinephrine. Epinephrine is also known as adrenaline, the hormone that triggers the "fight-or-flight" response when we are afraid. At chronic levels, these three hormones can harm the immune system's function as well as contribute to other detrimental health effects.
Berk also found that mirthful laughter raised good cholesterol and lowered inflammation during a test of the effects of laughter on diabetic patients.