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Meanwhile, elsewhere in the brain of someone about to laugh, the supplementary motor area executes a bunch of commands, sending signals to dozens of muscles and glands all at once. The whole business of a laugh is what scientists call "stereotyped." People may make different noises and faces, laugh at different intensities, and have a different sense of humor, but the commands human brains give out during a guffaw are a recipe followed precisely. Here's what happens throughout the body:Face Time: When we laugh, as many as 15 small muscles squeeze our faces into a smile. Increased blood flow there may turn us a bit pinker and give us a happy glow.
Eyes Have It: If the laugh is vigorous enough, our tear ducts can activate. Sometimes our glee can have a cumulative effect till we're literally crying with joy-and studies show that tears, whether happy or sad, may reduce symptoms of stress.
Mouth Off: Of course, our mouths open to let out those "ha-ha" rhythmic blasts of vocalized air. In addition, Loma Linda's Lee Berk and others have tested the saliva of patients after laughing episodes and found that they have higher levels of disease-fighting agents called immunoglobulins. Other studies have found higher blood levels of killer T-cells, suggesting that laughter may raise our immune function.
Vocal Point: Our vocal equipment has to roll up its sleeves to produce our high-pitched hysteria. The diaphragm, a strong muscle under the lungs, pumps down and up, filling the lungs and then blasting air out of them, up through the voice box to produce the laugh. A hearty guffaw is quite a workout for this system, requiring as much effort and volume as yelling. Because the lungs are exchanging much more air than normal, they enrich the blood with oxygen.
Wrestle Your Vessels: Our heart rate and blood pressure spike briefly when we laugh (especially when laughing while wrestling). They increase a bit even when we chuckle while sitting in a chair watching a funny movie. In addition to possible immune benefits noted earlier, laughter seems to help diabetics keep their glucose levels in check.
In a recent study, University of Maryland cardiologist Michael Miller investigated the effect of laughter on the inner lining of the blood vessels, or endothelium. Yep, even that part of our body produces chemicals-good ones when it expands, bad ones when it constricts. Miller put a pressure cuff on his subjects and blew it up to restrict blood flow for a few minutes. In the meantime, the victims (I mean subjects) watched a scene from a stressful movie (Saving Private Ryan) one day, and then a scene from a funny movie (There's Something About Mary or Kingpin) another day. Then Miller released the cuff and used an ultrasound machine to see whether the blood vessel lining expanded or contracted. By significant margins, it expanded after the funny movie and narrowed after Ryan. When the blood vessel lining expands, we get a shot of good chemicals like nitric oxide (not to be confused with nitrous oxide, or laughing gas), which reduces clotting and inflammation. When the endothelium contracts, we get a shot of stress hormones like cortisol, which make our blood clot and can lead, over time, to heart disease.
Pain Reliever: Whether in our extremities or up in our brains, laughter seems to have an analgesic effect: It increases our tolerance for pain. Back in 1987, Texas Tech psychologist Rosemary Cogan used the discomfort of a pressure cuff to test another medical benefit of laughter: pain management. Subjects who had watched a 20-minute Lily Tomlin routine could tolerate a tighter cuff than those who had watched an informational tape or no tape at all.
Belly Laughs: A hearty laugh can cause us to double over and tense all our major muscle groups for minutes at a time, leading Lee Berk to a simple conclusion: Laughter is exercise. He is fond of saying, "Laughter is inner jogging." The heart rate and blood pressure go up while you're laughing, but then they fall down below your baseline afterward, the same as with exercise. This could be very important exercise, Berk avers, for elderly and sick people who can't get out and run two miles.
According to Provine, early laughter researcher William Fry found that it took ten minutes on his rowing machine to elevate his heart rate to the same level provided by a good belly laugh, a finding that may have millions of Americans rationalizing their way out of the gym and back to reruns of Friends or I Love Lucy.
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