During full-blown laughter, air can rush out of your lungs at rates of 170 miles per hour. (Hafen, Brent Q., et al. Mind/Body Health. p 541-560. MA: Simon & Schuster, 1996.)
Benefits include stress reducer, improving performance, enhancing self-esteem, promoting creativity, strengthening the immune system, improving ability to negotiate and make decisions, increases breathing rate, clears mucus from lungs, increases oxygen delivered to cells, stimulates enzymes that function as natural laxatives, and improves digestion. (Hafen, Brent Q., et al. Mind/Body Health. p 541-560. MA: Simon & Schuster, 1996.
Laughter tends to expand lungs and increases blood and oxygen circulation similar to the way deep breathing or exercise does. Anger and stress do the reverse. (Greenwood-Robinson, Maggie, PhD. 20/20 Thinking. p 104. NY: Avery, Putnam Special Markets, 2003.)
Laughter may lead to coughing or hiccupping and coughing. This can help to clear the respiratory tract by dislodging mucus plugs. (Bartekian, Vatche. Laughter Can Cure What Ails You. Ask Men web site.)
Laughter has been shown to increase endorphin levels, stimulate immune function, reduce cortisol, stimulate circulation, massage internal organs, and have positive effects on the cardiovascular and respiratory systems. (Lubbe, Francois. UK Editor for The Healthier Life. Laughter has Potential Medical Benefits.)