His book, Anatomy of an Illness (New York: W.W. Norton, 1979), is a personal account of his cure. It was not only a bestseller, but it also helped to kickstart a new medical discipline: mind-body medicine, or 'psycho-neuroimmunology'. PNI, as it's now known, has firmly established hor-monal and other links between the mind and immune system, helping to explain, for example, how meditation and the placebo effect works.
Some of that research has included humour and laughter and, today, there is a small-but growing-dossier of medical studies trying to tease out their benefits, some of which appear to be substantial.
Does a lifetime of laughter help you to live longer? Actually, no. Analysisof the death rates among professional comedians has revealed that, in fact, they die sooner than the rest of us (Health Psychol, 1992; 11: 262-6). But laughter can make life easier while you're living-and not just by cheering you up.
Research by cardiologist Dr Michael Miller, of the University of Maryland, gives new meaning to the phrase 'hearty laughter'. Miller carried out a series of studies on humour and heart disease after being struck by how little his cardiac patients seemed to laugh. He decided to formally test this observation on the next 150 heart patients by using a simple question-naire designed to "measure the propensity to laugh under a variety of situations encountered in everyday life".
Compared with 150 healthy con-trols, he found that the heart patients "were significantly less likely to experience laughter during daily activities, surprise situations or social interactions". The statistical signifi-cance of the effect was far greater than for other standard risk measures such as cholesterol or high blood pressure (Int J Cardiol, 2001; 80: 87-8).
These findings set Dr Miller to wondering how it was that laughter-or the lack of it-could have an effect on the body. Following in Norman Cousins' footsteps, he used funny movies to check it out. He measured blood flow in viewers' arteries while they were watching clips from There's Something About Mary, a comedy, and Saving Private Ryan, a war movie. He found that laughter expanded the blood vessels, increasing blood flow to the heart by 22 per cent. Stress did the reverse, reducing the arterial lumen by 35 per cent (Heart, 2006; 92: 261-2).
"We believe that there is a direct effect of how our endothelium behaves, and the development and progression of heart disease," says Dr Miller. "We know that exercising and not smoking reduces the risk of heart disease. Regular, hearty laughter should probably now be added to the list."
Just how does laughter affect blood vessels? Researchers at Loma Linda University in California attempted to find the answer. Again, funny films were shown to volunteers, and their hormone levels measured afterwards. The researchers found significant reductions in the stress hormones cortisol and epinephrine, both well-known risk factors for heart disease (Am J Med Sci, 1989; 298: 390-6).
Encouraged by these results, the Loma Linda group widened their research to the immune system in general. This, too, showed that laughter offered major benefits, boosting the body's production of natural-killer (NK) cells, B cells, helper T cells and immunoglobulins. Some of these effects persisted hours after having seen the humorous video (Altern Ther Health Med, 2001; 7: 62-72, 74-6).
You'd expect that these positive findings would have spawned a whole raft of laughter therapies. However, although some hospitals have set up 'humour rooms' and mobile 'humour carts', they are merely for amuse-ment, not cure. Part of the problem is that there's still little hard clinical data that laughter is more than a stressbuster or mood-enhancer.
However, there's evidence that it can help to relieve pain (Psychol Bull, 2001; 127: 504-19), and tantalizing evidence that it can help diabetics by reducing blood sugar and preventing diabetes-related kidney disease (J Psychosom Res, 2007; 62: 703-6)-giving us glimpses of its potential.
There's only one clinic in the world that uses laughter as a core therapy-the Gesundheit Institute in Virginia. Its founder, Dr Patch Adams (famously portrayed by actor Robin Williams in the film of that name), is both a qualified doctor and a former clown. He hasn't published any evidence of his success rates, though-he's probably having too much fun to do so.
Laughing your head off
The dictionary defines laughter as "rhythmic, vocalized, expiratory and involuntary actions". Spontaneous contractions occur in the vocal cords and in 15 muscles of the face, while the epiglottis half-closes the larynx, causing gasping. Whereas emotions tend to involve only discrete parts of the brain, laughter uses most of the brain's primary areas-that is, the cortex, the frontal lobe and motor regions.