A laugh a day may help keep the doctor away, say a growing number of healthcare professionals. Laughter is like 'internal jogging,' a form of exercise that keeps the body and the mind fit. It can give the heart muscles a good workout, improve circulation, increase your pulse rate, fill the lungs with oxygen-rich air, decrease tension, and perhaps even relieve pain, says Donald Black, professor of psychiatry at the University of Iowa College of Medicine.

"People generally do feel better after laughing, and that's always good," Black says.

Laughter is the basis of what is called humor or laughter therapy, Black says. Humor therapists are studying how it reduces stress and may help treat illnesses.

"A good, hearty laugh--the kind that makes ribs ache and eyes water--can momentarily reduce the sensation of pain in the body," he says. It may be that laughter triggers the body's endocrine system to release hormones that send pain-killing chemicals through the body.

Because of this pain-killing effect, laughter may have a place some day in the treatment of painful diseases like cancer, he notes.

Laughter already is being used to treat other medical problems. Therapists have long used laughter to treat patients' depression. And some researchers recently have had success using laughter as part of the treatment of stroke patients.

Laughter is good even for people who aren't sick. Black says strong laughter gives people a mini-workout. When people laugh, their muscles contract, their pulse rates rise and their breathing is faster.

"Perhaps in a way it's like running, although people who run usually have a much longer workout than anyone could laugh," he says.

Despite these benefits, Black emphasizes that there is no scientific evidence that laughter will cure ailments.

But he encourages people to go ahead and laugh anyway. "It sure doesn't hurt," he says. "And it may help."

"Laughter, a reflex stimulated by emotion, is known to activate the cardiovascular system and may affect the immune system," Black says. "After the initial increase in pulse rate during laughter, there may be a brief decrease in pulse that could be associated with stress reduction. Humor or laughter therapy may help restore one's sense of well-being and enjoyment of life," Black says. "It may provide welcome relief during a lengthy hospital stay." Some hospitals now have special rooms, where patients can go to read humorous books and watch funny videos.

Humor therapists suggest adopting an attitude of playfulness and uncensored thoughts, practicing exaggeration--a traditional form of American humor--listening to tapes of funny jokes and stories, taking a humor-meditation break during a tense part of the day, and sharing laughter.

Other physical and mental exercises to create humor and reduce tension in daily life include making funny facial expressions, looking at funny photos of yourself, and making lists of what makes you especially happy.

Whatever the method of creating humor, it's an important part of our lives and helps us change and adapt to situations with creativity and imagination, Black adds.

If none of the above work for you, try drawing your stressful situation as a cartoon, making it as ridiculous as possible. In the process, you may see some humor in your situation and deal with it more effectively. Or, build a laugh library of humor writers, cartoons, records, tapes, pictures, and jokes.