And like physical exercise, they also appear to stimulate appetite, offering a potential way to help malnourished patients who are off their food. Californian scientist Dr Lee Berk said the effects of laughter mirrored those of repetitive exercise. Volunteers watched two 20-minute videos – one distressing and one humorous. There was a week between viewings to ensure the effects did not overlap.
No significant effect was seen after volunteers viewed the distressing video. But watching the humorous clip caused changes in blood pressure and Led levels of leptin to decrease as those of ghrelin went up. Similar effects are seen straight after moderate physical exercise, and are accompanied by an increase in appetite. Dr Berk said: ‘As the old biblical wisdom states, it may be true that laughter is a good medicine.’