“No pain, no gain” is a mantra often used to motivate those hard slogs at the gym. But could a daily dose of rib-tickling comedy reap some of the benefits of a gruelling workout? Lee Berk at Loma Linda University in California thinks so.
To assess the health benefits of laughter, Berk showed 14 volunteers 20-minute clips from humorous television programmes such as Saturday Night Live, measuring their blood pressure and cholesterol levels before and afterwards. The results, which he presented at the 2009 Association for Psychological Science meeting in San Francisco, should bring a smile to all lovers of levity. During the “laughercise” both cholesterol levels and systolic blood pressure fell. Direct comparison with exercise is difficult, but Berk estimates the physiological benefits were equivalent to those of a moderate 20-minute workout. Watching sombre scenes from Saving Private Ryan had no such effect.
That’s not all: laughter may also help fight off infection. Other studies have found that it boosts the performance of the immune system by increasing the production of antibodies and the activity of natural-killer cells. A mother’s laughter can even improve the quality of her breast milk, making it more effective at fighting skin allergies in newborn babies (New Scientist, 16 June 2007, p 23).
All this might suggest that you can laugh your way to a longer life. Unfortunately, what little evidence there is suggests quite the opposite. When Leslie Martin at La Sierra University in Riverside, California, compared data about the life history of 1215 Americans with their psychological profiles at age 10, she found that the most cheerful were also more likely to die young. In fact, a cheerfulness rating in the top quarter of the population increased the risk of death at any point in their life by 21 per cent over the risk for those who fell in the bottom quarter (Personality and Social Psychology Bulletin, vol 28, p 1155).
source : http://www.newscientist.com/article/mg20727691.700-laughters-secrets-the-best-medicine.html