Why Is Yawning So Contagious?

Researchers have identified new factors that make yawning contagious.

Posted Mar 16, 2014

Does looking at an image of a person yawning make you yawn? About half of adults yawn after someone else yawns due to a universal phenomenon called “contagious yawning.” Contrary to popular belief, a new study from Duke University suggests that contagious yawning is not strongly related to variables like empathy, tiredness, or energy levels.

Previous studies have suggested that there is a connection between contagious yawning and empathy. However, researchers at The Duke Center for Human Genome Variation found that contagious yawning may decrease as people age and may not be associated with empathy.

The study, titled “Individual Variation in Contagious Yawning Susceptibility Is Highly Stable and Largely Unexplained by Empathy or Other Known Factors,” was published March 14 in the journal PLOS ONE. This is one of the most comprehensive studies to examine the factors that influence contagious yawning to date.

"The lack of association in our study between contagious yawning and empathy suggests that contagious yawning is not simply a product of one's capacity for empathy," said study author Elizabeth Cirulli, Ph.D., assistant professor of medicine at the Center for Human Genome Variation at Duke University School of Medicine. The researchers emphasized that a better understanding of the biology involved in contagious yawning could ultimately lead to a better understanding of illnesses such as schizophrenia and autism. 

A 2010 study from the University of Connecticut found that most children aren't susceptible to contagious yawning until they're about four years old—and that children with autism are less likely to yawn contagiously than others.

In a study of about 30 6- to 15-year-olds with autism spectrum disorders (ASD), the Connecticut researchers found that children with ASD were less likely to yawn contagiously than their typically developing peers. Children with more severe autistic symptoms were much less likely to yawn contagiously than those with milder diagnoses.

Reading the Word Yawn Can Make People Yawn

Contagious yawning is a phenomenon that only occurs in humans and chimpanzees as a response to hearing, seeing, or even thinking about yawning. How many times have you felt the urge to yawn while reading this blog post? Studies have found that certain individuals are more susceptible to contagious yawning than others. 

Spontaneous yawning typically occurs when someone is tired or bored. Spontaneous yawning is first observed in the womb, while contagious yawning doesn’t begin until early childhood. The Duke study aimed to better define how certain factors affect someone’s susceptibility to contagious yawning.

The researchers found that certain individuals were less susceptible to contagious yawns than others. On average, participants yawned between zero and 15 times while watching a 3-minute video of people yawning. Of the 328 people studied, 222 contagiously yawned at least once. If you’d like to test your susceptibility to contagious yawning, watch this “Yawn-O-Meter” video. How long did you last before yawning?

In contrast to previous studies, the researchers at Duke did not find a strong connection between contagious yawning and empathy, intelligence, or time of day. The only independent factor that significantly influenced contagious yawning was age: as age increased, participants were less likely to yawn. However, age was only able to explain 8 percent of the variability in the contagious yawn response.

Conclusion: More Research on Contagious Yawning Is Needed

“Age was the most important predictor of contagious yawning, and even age was not that important. The vast majority of variation in the contagious yawning response was just not explained,” Cirulli concluded.

Ultimately, contagious yawning remains an unexplained mystery to scientists. The researchers at Duke are planning to study potential genetic influences that contribute to contagious yawning. Their long-term goal is to identify the genetic basis of contagious yawning as a way to better understand human diseases like schizophrenia and autism, as well as general human functioning.

“It is possible that if we find a genetic variant that makes people less likely to have contagious yawns, we might see that variant or variants of the same gene also associated with schizophrenia or autism,” Cirulli said. “Even if no association with a disease is found, a better understanding of the biology behind contagious yawning can inform us about the pathways involved in these conditions.”

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