From Science Daily
The greater your sense of humour, the less of the muscle-wrecking hormone cortisol you produce. Psychologists at the City University of Hong Kong discovered this when they did a study of 45 elderly men.
In humans cortisol levels rise as it starts to get light outside. Your cortisol level is highest just after you get up in the morning – unless your hormone system is out of balance because you get up at irregular times or you have a burnout. As the day wears on, your cortisol level goes down. The researchers measured the amount of cortisol in the men’s saliva just after they had got out of bed, and then 15, 30 and 45 minutes later.
The subjects were males aged between 64 and 84. As you age you start to produce more cortisol. Stress as a result of unpleasant events, anxiety or sadness also increases cortisol production. Studies suggest that the less their cortisol levels rise as they age, the healthier people are. Cortisol is also a bad news for athletes: it inhibits muscle growth, makes you more susceptible to injuries, sabotages the immune system and encourages the build up of fat reserves.
The psychologists were interested to find out whether humour inhibits cortisol. Previous studies have already shown that people who have a well-developed sense of humour experience everyday irritations as less stressful.
The figure below comes from a study that Millicent Abel did on students in the late 90s. [Humor 15–4 (2002), 365–81.]
The psychologists from Hong Kong assessed their subjects’ sense of humour with carefully worded questions such as “Do your problems get less if you try to see the humour in them?” or “Do you often try to see the funny side of tense situations?” This is a good way of sorting out the real humour lovers from the pessimists. At least, if you’re a psychologist.
The researchers divided their subjects into two groups, according to their responses: one with lots and one with little humour. The table below shows the amount of cortisol in saliva samples from the two groups. The dark figures are those for the group with a keen sense of humour.
So humour lowers cortisol levels – and yes, the relationship was statistically significant.
The researchers also measured the men’s self esteem. The higher this was, the more cortisol the subjects produced. This relationship was not statistically significant.
Biol Psychol. 2010 May;84(2):375-80.