Medical matters: One of my favourite TV channels is Paramount Comedy. And if I was confined to just watching just one programme each day it would have to be Frasier; thankfully Paramount offers regular reruns of the antics of the highly neurotic psychiatrist and his equally engaging brother, Niles.
Now there is scientific proof that comedy is good for your heart. A study presented at the recent Annual Scientific Meeting of the American College of Cardiology shows that laughing causes the tissue that forms the inner lining of blood vessels (the endothelium) to expand, increasing blood flow.
Researchers asked 20 healthy people to watch 15 minutes of Kingpin, a 1996 Woody Harrelson comedy. After a 48-hour break, the same volunteers were asked to view the opening battle scene from Saving Private Ryan.
After watching each film segment, researchers carried out a non-invasive ultrasound test to measure the changes in the reactivity of blood vessels. They found that blood flow increased by 22 per cent after watching Kingpin, but decreased 35 per cent after Saving Private Ryan. The average increase in blood flow after exercise is similar to that achieved by watching comedy.
Dr Michael Miller, the lead author of the study said: "There is great variability among people, but anything that evokes an emotional response has an impact on the heart." Put like that, and given the known relationship between stress and acute heart attack, it makes sense that laughter would be beneficial.
Nor is the power of laughter confined to heart health. There have been previous reports of skin rashes disappearing when patients with dermatitis watched a Mr Bean video. And a stand-up comedy act apparently helped lower blood glucose levels in patients with diabetes.
In the case of Mr Bean, the researchers demonstrated lower levels of a stress-related chemical in the blood, indicating that laughter triggered a positive reaction in the immune system of people with dermatitis.
Further evidence of a direct effect on the immune system comes from US research which found that people shown a comedy had higher levels of natural killer (NK) cells in the body. Low NK activity is linked to decreased disease resistance and illness complication in people with HIV and cancer.
The benefit of humour in helping to tolerate pain is well known; it had been thought this was simply by means of distracting the patient. But the possibility also exists that laughter may lessen the tension in muscles and contribute in a more direct way to the relief of symptoms.
Researchers at the Institute of Neurology in London claim to have located the brain's "funny bone". The medial ventral prefrontal cortex is a billiard-ball sized area of the brain that processes humour, sarcasm and irony. According to the researchers, the temporal lobes process jokes while word puns are analysed in the left side of the brain - an area concerned with speech.
Laughter is an intensely physical experience. After the brain has processed the incoming signals, it triggers the contraction of 15 muscles in the face. At the chortling and gasping stage, the voicebox gets partly covered, leading to irregular breathing. And, in those all too rare moments of helpless laughter, our tear ducts are stimulated and our faces redden.
By this stage in the process, laughter is clearly a highly aerobic form of exercise, and so the recently published findings really do begin to make sense. However, when Dr Miller was asked at the conference if laughter could now be prescribed as an alternative to physical exercise, he said: "We don't recommend replacing exercise with laughter as a public health measure."
To finish, a medical joke from a reader:
A consultant dies and approaches St Peter at the gates to heaven. Peter tells him, much to his dismay, that he must join the regular queue despite his eminence as a consultant. He reluctantly takes his place but within a few minutes a person wearing a white coat and stethoscope passes him heading for the gates.
The person nods casually at St Peter and continues into Heaven, without breaking his stride. The now irate consultant rushes up to St Peter and reminds him of what he said only a few minutes before: even consultants must go to the end of the waiting line. But, he said, a person who was clearly a consultant had been admitted without demur. He demanded an explanation. "Oh," said St Peter, "that was God - he just thinks he is a consultant."
Dr Muiris Houston is pleased to hear from readers at mhouston@irish-times.ie but regrets he cannot answer individual queries.