Watching comedy films is good for the heart because it boosts the flow of blood, a study says.
Watching comedy increased the flow of blood to the heart
A team from the University of Maryland in the US asked 20 healthy young adults to watch 15 to 30 minutes of sad and humorous films 48 hours apart.
While watching films such as There's Something About Mary, blood flow rose in all but one of participants.
Researchers said the effect was equivalent to starting a course of heart treatment drugs called statins.
But movies like Saving Private Ryan with its war scenes had the opposite effect, the Heart journal reported.
The team said it seemed likely that the act of laughing had the effect of widening the arteries - mental stress is known to narrow them.
Lead researcher Dr Michael Miller said that, even though more research was needed to confirm the findings, they would be of interest to cinema-goers.
"The overall difference in blood flow between the mental stress and laughter phases exceeded 50%."
And he added: "The extent of the impact of watching a sad film was of the same magnitude as remembering episodes of anger and doing mental arithmetic, while the impact of watching a funny film was equivalent to a bout of aerobic exercise or starting on statin treatment."
During the study, participants were asked to abstain from drinking alcohol, using vitamins or herbs, or taking aerobic exercise the evening before the experiment, as all these can affect blood flow.
In all, 160 measurements of brachial artery blood flow were taken before and one minute after phases of laughter or sadness. The brachial artery runs from the shoulder to the elbow, and is a good indicator of blood flow around the body.
Brachial artery blood flow was reduced in 14 of the 20 participants after watching film clips that caused distress, but increased in 19 of the 20 participants after watching those that elicited laughter.
Dr Charmaine Griffiths, of the British Heart Foundation, said: "It is well known that changes in emotion can be reflected in changes in the heart and circulation.
"Scientists are becoming increasingly interested in the possibility that a good giggle has positive effects on heart health.
"Whether sharing a joke with friends or watching a comedy, a good laugh is likely to be good for your heart.
"However, we would like to reassure people that watching sad films won't have any long term detrimental effects on the heart or circulation."