No laughing matter: humour can protect us from illness

In a famous case of contagious laughter in Tanganyika (now Tanzania) in 1962, a small outbreak of giggling among schoolgirls aged 12 to 18 started an extraordinary epidemic. The contagion of laughter spread through the population, touching people of all ages. The epidemic was so alarming that authorities closed schools. The episode lasted six months.

Was this just a giggling fit that somehow spread to the population as a whole? Brazilian behavioural biologist Silvia Cardoso does not think so. She believes it was caused by a freak virus that affected the part of the brain responsible for laughter.

This could be the explanation. But the laughter epidemic remains something of a mystery. Laughter, according to biologists and psychologists, is a formidable stress reliever and resistance booster in times of crisis, such as during epidemics. Studies suggest that this is because laughter reduces the production of hormones associated with stress - an effect that also benefits the immune system.

A better-documented demonstration of the power of laughter was produced by American writer Norman Cousins, who recounted his now-famous story in Anatomy of an Illness. Cousins was diagnosed with ankylosing spondylitis, a painful rheumatic disease, and was condemned to a diet of bland food and strong anti-inflammatory medicine. His felt he would never recover if he stuck to this regimen. Consequently, he devised his own: lots of vitamin C and long, daily doses of comedy shows. His book suggests that this approach had a significant degree of success.

Many of laughter's beneficial effects begin in the body, which is why it is known as one of the best possible 'inner workouts'. It sets in motion the cardiovascular system. The heart rate and blood pressure increase and the arteries dilate. This causes blood pressure to fall. The short, repeated actions of laughter are accompanied by vigorous contractions of the chest muscles, diaphragm and abdomen, which increases blood flow into our internal organs. Giggling also loosens the tension in our muscles. And it appears to release endorphins into our brains, which can lessen sensitivity to pain, increase endurance and enhance sensations of pleasure.

Comedy and jokes emerge with unusual vigour during times of crisis or adversity because we instinctively seek them out for their ability to provide a form of relief, notes psychologist Paul Wong, of Trinity Western University in Canada. Black humour in particular, he believes, helps us detach ourselves from circumstances by laughing at the situation and also at ourselves.

But in some situations - such as the present one in Hong Kong - isn't humour disrespectful? Aren't jokes in bad taste because they are being made at the expense of other people's suffering?