A Killer Joke
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.
A Bloody Good Time
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.
Milking It for Laughs
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.
Wait For It...
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.
Laugh One, Laugh All
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