It happens every so often that when a person yawns, it starts off a domino effect and everyone starts yawning. There’s even an official name for it: contagious yawning.
Scientists say that this happens for 60-70% of people. Now, a new study notes that not only is yawning contagious, but suppressing one can make the urge even stronger, resulting in bigger yawns, TIME reports. It provides more information as to why people tend to yawn when others do, suggesting that the impulse behind contagious yawning is linked to the level of activity in people’s brains. The urge to yawn is almost impossible to resist, the study found.
Researchers tracked 36 adult volunteers for the study. They stimulated the participants’ brains magnetically to measure the activity of nerves in certain regions of the brain. The focus was on the motor cortex, as this is what controls planning and movement.
The measurements allowed the researchers to quantify how “excitable” the motor cortex was in each person, which they theorized would tell how much they were affected by contagious yawning.
The researchers showed the participants video clips of people yawning. Half of them were told to ignore the urge to yawn, while the other half were told to yawn when they felt like it. The reactions were videotaped, and the researchers counted the number of times each participant yawned, as well as the type of yawn involved.
Those who were told not to yawn ended up doing fewer wide-open-mouth yawns, but there were more stifled yawns among the participants, and they said that they had stronger urges to yawn than the other group.
The study found that a person’s propensity for contagious yawning depended on how excitable his or her motor cortex was. Stephen Jackson, professor of cognitive neuroscience at the University of Nottingham and lead author on the study, said,
Some of us have very excitable motor networks and are very susceptible to contagious yawning, while others are much less so.
Understanding why people yawn and what triggers the urge may help doctors when it comes to psychiatric and neurological conditions, Jackson said. “Studying contagious yawning helps us to understand the brain mechanisms that give rise to tics. If we can understand how alterations in cortical excitability give rise to neural disorders, we can potentially reverse them.”
The study was published in Current Biology.
