Laughter

Milton Berle once said: Laughter is an instant vacation. Now science has added some concrete proof top that statement or so suggests a new study from an international research team, led by Oxford University. The study found that when we laugh properly, as opposed to producing a polite titter, the physical exertion leaves us exhausted and thereby triggers the release of protective endorphins. These endorphins, one of the complex neuropeptide chemicals produced in the brain, manage pain and promote feelings of well being.

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Laughing is a reaction to certain stimuli, fundamentally stress, which serves as an emotional balancing mechanism. Traditionally, it is considered a visual expression of happiness, or an inward feeling of joy. It may ensue from hearing a joke, being tickled, or other stimuli. It is in most cases a very pleasant sensation.
The fact that only this type of laughter releases endorphins has probably evolved as a way of promoting socializing amongst humans, says the paper. It points out that many studies have already shown that laughter is 30 times more likely to occur if you are with others than when alone. The endorphin rush appears to be limited to a good belly laugh, shared with others.

A link between laughter and healthy function of blood vessels was first reported in 2005 by researchers at the University of Maryland Medical Center with the fact that laughter causes the dilatation of the inner lining of blood vessels, the endothelium, and increases blood flow. Drs. Michael Miller (University of Maryland) and William Fry (Stanford), theorize that beta-endorphin like compounds released by the hypothalamus activate receptors on the endothelial surface to release nitric oxide, thereby resulting in dilation of vessels. 

The research paper makes an important distinction between relaxed, unforced laughter that creases the eyes, and polite laughter which does not reach the eyes. It concludes that when we laugh properly we produce a series of exhalations without drawing breath, an involuntary physical mechanism that is limited to humans and appears to trigger the release of endorphins. Laughter is important to other great apes too but they breathe in as well as out when they laugh, unlike humans.
The paper is based on more than ten years of research in which different experiments were staged to discover what determined our level of pain tolerance. Subjects were asked to watch TV clips or live staged shows, and their pain thresholds were measured before and after doing this using a number of different pain manipulations (ice-cold sleeves, pressure from a blood pressure cuff, and a painful, strenuous quad work-out).

The participants watched 15 minute clips from comedies like Mr Bean and Friends, and these were contrasted with clips on how to play golf or factual programs, both designed to elicit a neutral response. In other experiments, they watched nature programs designed to produce a positive, feel-good quality; however, like the golf instruction clips, these did nothing to increase the pain threshold, suggesting that it is the endorphin-activating effects of laughter itself that is important, not just the feel-good factor. 

Another experiment compared the pain thresholds of participants who had watched stand-up comedy at the Edinburgh Fringe Festival with those who sat through staged dramas. This experiment confirmed that the pain tolerance effect of shared laughter is not just something confined to the laboratory, but occurs in real life too.
Lead author Professor Robin Dunbar, Head of the Institute of Social and Cultural Anthropology at the University of Oxford, said: "Very little research has been done into why we laugh and what role it plays in society. Using microphones, we were able to record each of the participants and found that in a comedy show, they laughed for about a third of the time, and their pain tolerance rose as a consequence. We think that it is the bonding effects of the endorphin rush that explain why laughter plays such an important role in our social lives."

In both primates and humans, laughter has been found to play an important role, yet has received very little attention in academic literature. This latest paper supports other work by Professor Dunbar that suggests the importance of group activity in producing endorphins. A previous study by Professor Dunbar and Dr Emma Cohen found that members of a rowing team increased their pain tolerance by training as a group rather than as individuals. Other communal activities like music making, dancing and religious rituals have also been shown to create euphoric states which, according to some studies, can also be associated with the release of endorphins.

For further information: http://www.ox.ac.uk/media/news_stories/2011/111409_1.html