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Studies Why does yawning so contagious?
You've probably already experienced this phenomenon yourself: you see another man yawn and suddenly you have to yawn too. But what's behind this effect? Why is yawning so contagious? Researchers found that about 60 to 70 percent of people are infected by the yawning of other people. In addition, trying to suppress the yawning tends to make the urge to yawn even stronger.
Researchers at the University of Nottingham have found in their recent research that yawning is often contagious and suppression of yawning tends to increase urgency. The physicians published the results of their study in the journal "Current Biology".
Yawning is contagious to most people, but what is behind this effect? (Image: Piotr Marcinski / fotolia.com) Yawning is associated with brain activity levels in humans
The researchers tried to find out why some people are yawning when other people yawn near them. Previous studies have already found that the effect has little to do with empathy. The results of the new study indicate that the infectious effect of yawning in humans appears to be linked to brain activity levels. The urge is almost impossible to ignore, the researchers add.
Physicians examine 36 volunteer subjects
The new study included a total of 36 adult participants. The scientists magnetically stimulated the brains of the subjects. This allowed them to measure how active nerves were in certain areas of the brain. The experts focused on the so-called motor cortex, because this area is responsible for motor skills. The measurements helped the physicians to quantify how easily the motor cortex was stimulated. This led them to predict how strong the subjects' propensity was for so-called contagious yawning.
The urge for contagious yawning is not the same for all people
Afterwards, the scientists showed the participants video clips of yawning people. Half of the subjects were allowed to yawn at will, but the other half were instructed to resist the yawn. The experts found that every person feels the urge to yawn when he sees other people yawning. However, this urge is not equally pronounced in all persons. Also, it will be harder not to yawn if it is to be suppressed.
Excitability of the motor cortex determines susceptibility to contagious yawning
The likelihood of infection from other people's yawning is directly related to how excitable the affected person's motor cortex is. Some of us have a very excitable motor cortex and are therefore very prone to contagious yawning, explains author Professor Stephen Jackson of the University of Nottingham.
Electrical brain stimulation increased excitability of the motor cortex
In a separate experiment, the researchers tested this theory and found that mild electrical brain stimulation triggered increased excitability of the motor cortex. This in turn increases the propensity for contagious yawning. This effect may still be important for the understanding of other neurological conditions, explain the physicians.
By understanding about contagious yawning, we learn a lot about other illnesses
Infectious yawning is a form of echo phenomenon, which is an automatic imitation of words or actions, the experts explain. This feature is also seen in various diseases such as epilepsy, dementia, autism and Tourette syndrome. Understanding why yawning can be contagious is important because it also teaches a lot about the neurological and psychiatric disorders mentioned above, the researchers add.
Results of the study could help in the treatment of so-called tics
If, for example, the excitement of patients with Tourette's syndrome could be reduced, this would reduce the involuntary movements and outbreaks (so-called tics), explain the physicians. By studying the contagious yawn, it will be possible to better understand the brain mechanisms that trigger the tics, explains the author Professor Jackson. "If we can understand how changes in cortical excitability lead to neural disorders, we may be able to reverse them," the expert adds. (As)