“That doesn’t surprise me at all,” says Dr Berk. When he took blood samples via intravenous angiocatheters as subjects watched a pre-selected comedy video, the samples showed that levels of stress hormones decreased substantially after laughing.

“It is these stress hormones, such as cortisol, that modify progesterone levels and could affect the implantation of a foetus,” he says. “We did a similarly compelling experiment, published in The American Journal of the Medical Sciences, when we selected about 60 diabetic heart patients at high risk of a second heart attack and split them into two groups. Around 30 underwent standard cardiac rehab therapy, the other half watched a video they found funny for at least 30 minutes a day, Monday to Friday. We monitored the two groups every month over a year and we noticed substantial decreases in detrimental stress hormones in the laughter group, who ultimately needed less medication and had fewer recurrent heart attacks than the other group: 42 per cent versus 8 per cent.

“If you or I had come up with a pill that did that, we would be on our way to Sweden to collect a major prize. Yet laughter has the ability to do that.”

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It works, says Dr Berk, because there is a connection between the brain, hormones, the nervous system and the immune system. “Laughter produces all kinds of things that help our immune systems. Each immune cell has a receptor which looks like a satellite dish, and when substances such as endorphins or growth hormones are plugged in, cells are told to increase activity. Adversely, if cortisol generated from distress is plugged in, activity is decreased.”

Laughter and pain relief is another area being explored. Down the road from Dr Berk, Margaret Stuber and Lonnie Zeltzer, two cancer researchers at the University of California (UCLA), head a project dubbed Rx laughter, a non-profit charity that researches and implements laughter initiatives to improve medical conditions.

One such project is looking at how laughter affects the pain levels of patients aged between 7 and 18 who are facing life-threatening illness. They have already found that the children can deal with a painful medical procedure significantly better while laughing at a comedy show, and by taking low-invasive measurements of the children’s heart rates, blood pressure and hormones, they hope to establish why.

“I think we are going to learn that exposing yourself to humour will not only change mood and stress hormones but also influence serotonin levels, which are involved in the pain control system,” says Zeltzer. “That would mean that laughter could have an effect on chronic pain over time and enhance immunoreactivity, as well as helping with depression and sleep and anxiety disorders.”

In a way, it was Cremer’s realisation that laughter had healed him that catapulted him into his chosen career. Having suffered from depression 12 years ago, he realised that his work as an improvisation comedian made him feel better physically as well as mentally, so he became a laughter coach. He sees no difference between paying to see a stand-up comedy show at the Edinburgh Fringe and attending a laughter class in your lunch break.

“There is a huge demand for laughter, and I see it as a symptom of how far Western societies have lost themselves,” he says.

“We live in an isolated world with no sense of community. As well as all the mental and physical benefits that laughter brings, it has been said to be the shortest distance between two people, and I think that this social element is one of its keys. We never laugh alone. Is it odd that we need to pay someone to encourage us to laugh? I think it’s great that we are realising the power of laughter and encouraging it, rather than sitting at home in front of the television.”

Dr Berk couldn’t agree more. “People think that the concept of getting together to laugh for no good reason is silly — but take going to the gym. Where are they all running to? Medical science needs to get serious about silliness — and the sooner it does so, the healthier we will be.”

DOCTOR, DOCTOR, HOW CAN I LEARN TO LAUGH MORE?

You can’t teach yourself a sense of humour but you can teach yourself to laugh more.