The Science of Laughter

Far from mere reactions to jokes, hoots and hollers are serious business: They're innate -- and important -- social tools.

By Robert Provine, published on November 01, 2000 - last reviewed on April 11, 2005

Laughter is an energetic activity that raises our heart rate and blood pressure, but these physiological effects are incompletely documented and their medicinal benefits are even less certain. Lennart Levi, of the Karolinska Institute in Stockholm, reported that comedy activates the body's "fight or flight" system, increasing catecholamine levels in urine, a measure of activation and stress. Lee Berk, DHSc, of the Loma Linda School of Medicine, countered with a widely cited study that reported that laughter reduced catecholamines and other hormonal measures of sympathetic activation. This reduction in stress and associated hormones is the mechanism through which laughter is presumed to enhance immune function. Unfortunately, Berk's studies show at best a biological response to comedy. His reports included only five experimental subjects, never stated whether those subjects actually laughed, and were presented in only three brief abstracts.

Does a sense of humor or a lighthearted personality add years to your life? Not necessarily. A large-scale study by Howard Friedman, Ph.D., professor of psychology at the University of California at Riverside, found optimism and sense of humor in childhood to be inversely related to longevity. This may be because people with untempered optimism indulge in risk-taking, thinking, "I'll be okay."

Pain reduction is one of laughter's promising applications. Rosemary Cogan, Ph.D., a professor of psychology at Texas Tech University, found that subjects who laughed at a Lily Tomlin video or underwent a relaxation procedure tolerated more discomfort than other subjects. Humor may help temper intense pain. James Rotton, Ph.D., of Florida International University, reported that orthopedic surgery patients who watched comedic videos requested fewer aspirin and tranquilizers than the group that viewed dramas. Humor may also help us cope with stress. In a study by Michelle Newman, Ph.D., an assistant professor of psychology at Penn State University, subjects viewed a film about three grisly accidents and had to narrate it either in a humorous or serious style. Those who used the humorous tone had the lowest negative affect and tension.

A problem with these studies is that none of them separate the effects of laughter from those of humor. None allow for the possibility that presumed effects of laughter or humor may come from the playful settings associated with these behaviors. And none evaluate the uniqueness of laughter by contrasting it with other vocalizations like shouting.

Rigorous proof that we can reduce stress and pain through laughter remains an unrealized but reasonable prospect. While we wait for definitive evidence, it can't hurt -- and it's certainly enjoyable -- to laugh. So, a guy walks into a bar...