Fifteen muscles in your face contract during laughter, including the stimulation of the zygomatic major muscle (that’s the one that lifts your upper lip), which is why you can spot a real laugh from an insincere one.
It enhances your intake of oxygen-rich air, stimulating your heart, lungs, muscles and brain. In a fit of giggling, your respiratory system responds by the epiglottis half-closing the larynx, causing air intake to occur irregularly. The struggle for oxygen is the same reason your face goes red and why that friend of yours always snorts like a pig.
A hearty chuckle boosts your metabolism… a bit. “It’s sadly not true, however, that laughter burns more kilojoules than going for a run,” says neuroscientist Professor Sophie Scott. In reality, it torches an extra 40–165kJ (10–40 cals) for every 10–15 minutes of laughing. “You would have to laugh solidly for up to three hours to burn off a packet of salted crisps,” she says.
Laughter boosts your heart rate by 10 to 20 per cent, while, at the same time, it lowers your blood pressure and can reduce your risk of heart attack. It’s a simple way to live longer and actually enjoy the time you have.
Studies have shown that people score better on memory and cognition tests after a good belly laugh. This is possibly because of the extra oxygen stimulating blood flow (and essential nutrients) through the brain.
A serious bout of the giggles not only significantly decreases the stress hormone cortisol (another reason why your blood pressure goes down), it also releases a surge of the happy hormones endorphins and dopamine and could help stabilise your moods. “Laughing may help control brain levels of the neurotransmitter serotonin, similar to what antidepressants do,” says cognitive psychologist Janet Gibson.
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