London - The ability to withstand pain is increased after a good laugh because it triggers the release of chemicals that act as a natural painkiller.
Research at Oxford University in 2011 looked at two groups of adults — one was shown 15 minutes of comedy videos, while the other a “boring” 15-minute film about golf.
Those who had a good belly laugh were able to withstand up to 10 percent more pain from holding a bag of ice on their arm than they had been before watching the videos. However, those in the golf group were less able to bear the pain. And it seems that only a good guffaw had this effect — tittering and giggling had no benefit.
Slapstick humour seemed to score highly, whereas clever stand-up comedy routines, though found to be enjoyable, had no effect on raising pain thresholds.
Uncontrollable laughter is thought to release chemicals called endorphins which, as well as generating mild euphoria, also dull pain by binding to pain receptors in nerve cells and impeding the transmission of pain signals. - Daily Mail