Yawning is so contagious that one sleepy person in a room can easily set off the rest.
But anyone trying to stifle their yawns at a particularly dull work meeting or date is fighting a losing battle, scientists have found.
However much you try not to look bored by yawning, you will yawn just the same amount, it has emerged. And trying to stifle a yawn by keeping your mouth tightly shut will only make you want to do it more.
Scientists at Nottingham University made the discovery after showing 36 adults video clips of yawning to study the copycat effect.
They say yawning, much like coughing and urinating, is something you feel driven to do more when you know you can’t or shouldn’t.
However much you try not to look bored by yawning, you will yawn just the same amount, it has emerged in the latest study
Study leader Stephen Jackson, professor of cognitive neuroscience at Nottingham University, said: ‘This contagion effect is highly individual, with some people yawning 30 times in our 10-minute session and some not at all.
‘When people try not to yawn there is a tension in the brain, in the primary motor cortex which controls yawning, which wants to cause this action. This may be why it cannot be stopped and people feel a greater urge to do it.’
Humans, dogs and chimpanzees all suffer from contagious yawning, making them more likely to do it after someone else does.
It has been suggested copycat yawning is linked to empathy, meaning you can spot a psychopath because they won’t yawn along with other around them.
YAWNING LINKED TO INTELLIGENCE
Next time you try to stifle a yawn, it might be worth discarding polite etiquette by letting your mouth gape for as long as you need because it could help to reveal how smart you are.
Biologists have discovered a surprising relationship between the length of time mammals yawn for and how big and complex their brains are.
They believe it may also be a sign of greater cognitive ability.
Primates, including our own species, tend to have the longest yawns of all compared to other species – up to 50 per cent longer.
The findings last October helped to suggest a possible role for why yawning evolved – it helps to cool the brain.
Writing in the journal Biology Letters, researchers at the State University of New York at Oneonta, said it appeared yawning duration may be related to cognitive capacity too.
How was the study carried out?
The Nottingham researchers asked people to watch a video of others yawning, telling them to yawn as much they liked. On a second occasion, they watched the same video but with the instruction to stifle the reflex.
When practising self-control, the group recorded an average of 0.17 full yawns and 3.86 stifled ones over 10 minutes. But their efforts to look less tired had clearly failed, because they yawned just as many times as under normal conditions.
However, when asked to record the urge to yawn on a sliding scale, those asked to rein it in found they wanted to do it much more.
What do the findings mean?
The results could help to treat people with dementia, for whom one of the symptoms is finding it harder to stop themselves mimicking others’ yawning and coughing.
The practice of automatically and unconsciously copying others’ behaviour is known by experts as echophenomena.
Professor Jackson said: ‘We suggest that these findings may be particularly important in understanding further the association between motor excitability and the occurrence of echophenomena in a wide range of clinical conditions that have been linked to increased cortical excitability and/or decreased physiological inhibition such as epilepsy, dementia, autism, and Tourette syndrome.’