Science of Laughter

Also, researchers from the University of Maryland studied 20 young volunteers and found that the flow of blood in their brachial artery - the major blood vessel in the upper arm - was increased in those who watched a comedy film compared to those who watched more serious films. Of those who watched the films which generated laughter, 19 of the 20 volunteers had increased blood vessel relaxation.

So should we all start a course of laughter, three times a day and before meals? Unfortunately, these studies were done in small numbers of volunteers and were not blinded or randomised, so it is hard to make any definite conclusions regarding the health benefits of laughter. It is difficult to control for individual personalities, social situations or general attitudes to life in these trials. Dr Harry Witchel of the Department of Physiology at the University of Bristol is sceptical about the evidence for laughter as a miracle treatment: "It is not a cure for any disease," he says. "There are a variety of conditions where it might improve certain cases, for example, in psychological stress-based disorders or for people on in vitro fertilization (IVF) programmes."

Until there is good scientific evidence that regular laughter prolongs life, the health benefits of laughter will be controversial. In social situations, however, laughter is a natural mechanism we use to help interactions go smoothly. Professor Christie Davies, a sociologist from the University of Reading and author of the book The Mirth of Nations, says that for social reasons, we feel that we have to keep a conversation going and laughter is one method we use. "It is a social noise that people are not conscious they are making," he says.

It does seem intuitive that laughter is a good thing and everyone feels better after a good chortle. It may not be the magic treatment for all ills, but it does no harm and improves quality of life. So perhaps laughter is no joke after all.