By Matthew Hutson, published on May 1, 2008 - last reviewed on October 22, 2010
Name: Chelsea Peretti
Age: 12 (on the inside)
Who's better at finding comedy-gold in a rough world than a self-deprecating comedian? "It helps to have a sense of humor about yourself," Peretti says. Peretti's a rising star in New York's stand-up scene, with a strong Web presence and a TV pilot in the works.
How would she describe her own laugh? "There's a difference between a laugh where you're like 'ha ha, good joke,' and one where you're caught off guard. And, of course, when I'm with my boyfriend my laugh is really cute and giggly."
Chuckling heartily pumps up the expression of at least 14 genes that regulate natural killer-cell activity. These immunological assassins destroy tumors and cells besieged by viruses on contact.
Laughter causes the inner lining of blood vessels to expand, increasing blood flow. Such vasodilation, also caused by aerobic activity, may be the result of a heaving diaphragm or the release of endorphins.
Breast-feeding mothers have even more reason to laugh. Watching a funny movie increases levels of the relaxing hormone melatonin in breast milk. And drinking the milk reduces allergic reactions in infants with atopic eczema.
Got diabetes? Some gentle ribbing could save your kidneys. Laughter increases their receptors for certain proteins that prevent cellular damage in diabetics. It also curbs the spikes in blood glucose after meals, either through muscle use or changes in neuroendocrine levels.
Just the expectation of laughter can work wonders. Blood drawn from people right before they watched a comedy showed a beta-endorphin increase of 27 percent and a human growth hormone boost of 87 percent. Endorphins help the immune system, while HGH is good for muscles, bones, and internal organs.
A contagious laugh promotes bonding, reduces stress, and spreads the wealth of laughter's physical benefits. And we're programmed to capitalize on it: Just hearing laughter activates neurons in the premotor cortex that prepare the face to smile.
Sources: 1) Biomedical Research 2) American College of Cardiology conference 3) The Journal of Psychosomatic Research 4) The Journal of Psychosomatic Research and Diabetes Care 5) Experimental Biology conference 6) The Journal of Neuroscience