Why is Yawning Contagious

From Mirror Neurons to Social Empathy: Unpacking the Complexities of Contagious Yawning

J. C. Lai

Have you ever noticed that when you look at someone yawning, you do it too? The term for this phenomenon is called contagious yawning and there is no scientific consensus to why it happens, making it “the least understood, common human behaviour.” However, a look at the various scientific theories proposed may give us a better understanding on the complexities of contagious yawning.

Before we look into why yawning is contagious, we must first look into why we yawn in the first place. Similar to the phenomenon of contagious yawning, the practice of yawning in itself is unknown and there are multiple theories that attempt to explain it. 

The main line of argument is that yawning helps regulate brain temperature, or what scientists call thermoregulation. Much like a computer, the brain functions the most effectively and efficiently at a certain temperature. To prevent overheating, we yawn to increase our heart rate, blood flow, and muscle use, all of which are essential to cool the brain. Since exhaustion and sleep deprivation both increase brain temperature, this explains why yawning occurs more often when we’re tired.

Another theory proposes that we yawn in order to wake our bodies up. The motion of yawning supposedly stretches and lubricates our lungs and their tissues, alongside our body’s muscles and joints, which in turn encourages blood flow around the body and into our face and brain, which increases overall alertness and cognitive behaviour.

A study by the University of Maryland found that the likelihood of yawning increases sixfold after seeing someone else yawn. More interestingly, the reason for contagious yawning is unrelated to the reasons why we yawn mentioned above.

Neuroscientists suspect that yawn contagion is a marker of social empathy as a result of the mirror neurons in the brain. These neurons cause our bodies to copy and impersonate the actions of the people in order to allow us to learn, be self-aware and relate to others around us. A range of evidence supports this theory. Contagious yawning begins in children around the age of 4-5, which is around the same time that empathetic behaviour and the ability to identify emotions begin to develop in the prefrontal cortex of children. Furthermore, people who suffer from empathy related disorders, such as autism and schizophrenia, have significantly lower rates of yawn contagion, which supports the theory of yawning contagion. A recent study by the University of Turin also found that yawning is more contagious with someone who we are socially or genetically close to, such as our family and friends. The phenomenon is not limited to humans, with animals such as dogs also being more susceptible to yawning contagion by its human owners. This can be attributed to us feeling more empathetic for those who we are closer to, hence reaffirming the theory.

On the contrary, another theory proposes that yawning is a form of indirect and unintentional social communication. Yawning, as an ancient, evolutionary conserved behaviour shared among many vertebrate animals, may have helped our ancestors evoke their feelings of a certain experience as unpleasant or boring, and has trickled down to today’s generation.

The average human yawns about 20 times a day, yet we have no conclusion on why we do it nor why it is contagious. Next time you yawn, think about whether you’ve yawned because you’ve caught it from another, tired, or bored. Maybe you can even prove or disprove some of the theories mentioned above.