Doctors examined whether yawning can really be infected
You have probably already experienced this phenomenon yourself: you see another person yawning and suddenly you also have to yawn. But what is behind this effect? Why is yawning so contagious? Researchers found that about 60 to 70 percent of people get infected by yawning other people. In addition, the attempt to suppress yawning seems to rather lead to the urge to yawn being intensified.
In their current research, the University of Nottingham scientists found that yawning is often contagious and that suppressing yawning tends to lead to an increased urge. The doctors published the results of their study in the journal "Current Biology".
Yawning is associated with brain activity levels in humans
In their investigation, the experts tried to find out why some people are more likely to yawn 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 to ignore the urge is almost impossible, the researchers add.
Doctors examine 36 volunteers
The new study included a total of 36 adult participants. The scientists magnetically stimulated the test subjects' brains. This allowed them to measure how active nerves were in certain areas of the brain. The experts concentrated on the so-called motor cortex, because this area is responsible for motor skills. The measurements helped the doctors to quantify how easily the motor cortex could be stimulated. This made them predict how strong the tendency for the so-called infectious yawning was among the test subjects.
The urge to infect yawning is not equally pronounced in all people
The scientists then 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 yawning. The experts were able to find out that everyone feels the urge to yawn when they see other people yawning. However, this urge is not equally pronounced in all people. It will also be harder not to yawn if it is to be suppressed.
Excitability of the motor cortex determines susceptibility to infectious yawning
The likelihood of infection by yawning other people is directly related to how excitable the motor cortex of those affected. Some of us have a very excitable motor cortex and are therefore very susceptible to infectious yawning, explains the author Professor Stephen Jackson from 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 slight electrical brain stimulation triggered increased excitability of the motor cortex. This in turn increases the tendency for infectious yawning. This effect can still be important for understanding other neurological conditions, explain the doctors.
By understanding infectious yawning, we learn a lot about other diseases
The infectious yawn is a form of echo phenomenon, which means an automatic imitation of words or actions, the experts explain. This characteristic can also be observed in various diseases such as epilepsy, dementia, autism and Tourette syndrome. Understanding why yawning can be contagious is important because it also means that a lot can be learned about the above-mentioned neurological and psychiatric disorders, the scientists add.
Results of the investigation could help in the treatment of so-called tics
If, for example, the arousal of patients with Tourette syndrome could be reduced, this would reduce the involuntary movements and outbreaks (so-called tics), the doctors explain. By studying infectious yawning, it becomes 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," added the expert. (as)