Stop Making Me Yawn

Whether you are waking up from a long nap or staying up late studying for finals, the impulse to yawn can seem unavoidable. Just like blinking or breathing, yawning is a universal experience. However, the process of yawning is special due to its ability to be contagious. If people around you are yawning, you are far more likely to yawn as well. Yawns are typically associated with fatigue and tiredness, but ongoing research has found evidence supporting new theories surrounding this involuntary phenomenon. 

Yawning is a reflex that involves a deep inhalation, widening of the jaw, and a rapid exhalation of air. This benign phenomenon has been widely analyzed by renowned scientists, but only theories for its cause have arisen over the years. One theory revolves around equalizing air pressure surrounding the ear drums. Traveling inside an airplane or driving through a tunnel causes the air pressure around the ears to change drastically, resulting in the well-known popping sensation that we have likely all experienced. To combat this, yawning helps equalize the air pressure by opening the Eustachian tubes, which connect the ears to the throat. Another theory on why yawning exists is to regulate the brain’s temperature. Since the brain produces heat energy from its many processes, increasing airflow helps decrease the brain’s temperature, allowing for ideal neural activity to continue. Though yawning is typically associated with exhaustion, it has also been theorized that the action helps us stay alert. This makes biological sense, as being tired limits reflex mobility, thus creating an undesirable vulnerability. The process of yawning is facilitated by molecules like oxytocin and dopamine, which release neurotransmitters such as adenosine and catecholamines. These neurotransmitters are normally associated with increasing alertness, providing an effect similar to caffeine. Yawning has been shown to be more frequent during slow, non-interactive activities––when oxytocin and dopamine are at their peaks. Though these theories explain the cause of yawning, none of them provide a reason for its contagiousness.

A plausible theory explaining contagious yawning comes from the evolutionary context behind humans and chimpanzees (e.g. group hunting). Yawning is believed to be an ancient method of communication between members of a group. Researchers suspect that yawning was able to indicate the conditions of the environment, conveying if it was safe enough to sleep in an area or if the group should search for a different location. This method of communication allowed for social alertness and increased cognitive performance within ancient primate groups of these species. Interestingly, while yawning has been shown as a common trait in almost all mammals, contagious yawning has only been seen in humans and chimpanzees. Among other mammals like dogs, there is limited evidence supporting the occurrence of contagious yawning. Moreover, as actions like laughter and weeping have the ability to be contagious, yawning can also be attributed to this family of spontaneous reactions. Researchers have classified emotions like laughter and crying as positive interactions, as they convey feelings that strengthen connections. This could be by diffusing tense situations through joy or indicating comfort. As yawning is capable of conveying feelings like comfort, relaxation, and collective boredom, its importance is thought to be on par with other emotional responses.

However, the theory that is most probable is the correlation between contagious yawning and social empathy. Contagious yawning is theorized to be derived from social mirroring—unconscious imitation of another’s actions, behaviors, or attitudes. Special brain cells called mirror neurons are responsible for this, firing either when we perform an action or when others are observed performing the same action. Applying this concept, psychologists have proven that more empathic people (i.e. stronger ability to sense other people’s feelings) are more likely to undergo contagious yawning. Empathic people tend to experience more social mirroring, as their mirror neurons are more tuned to interpreting the actions of others. 

Contagious yawning occurs more frequently between people who share a social bond. For instance, the likeliness of yawning from another person’s yawn would be higher if the individuals were family members rather than complete strangers. In other words, the strength of social bonds is proportional with the probability of contagious yawning due to increased empathy. An experiment was conducted based on this theory: When viewing a video of their mothers yawning, 22 young children responded by yawning, but upon viewing videos of other people performing the same action, most did not yawn. It was also concluded that children under four contagiously yawn less, as their mirror neurons and ability to understand the concept of empathy are less developed. 

Another well-studied concept is when yawns typically occur. Most of the time, yawns occur during sleep inertia. Sleep inertia is associated with the period of time before and after you normally sleep. Adenosine, a neurotransmitter that promotes sleep, builds up during the day to regulate sleep. To fight the build-up of adenosine, your body attempts to wake itself up through yawning to increase brain activity and blood flow. Furthermore, disruptions to the circadian rhythm result in irregularities in the amount of adenosine within the body, therefore causing additional yawning at sleep-wake cycles. 

Even with the extensive research regarding yawning and contagious yawning, only theories have arisen. Though yawning is often dismissed as an insignificant and even disrespectful gesture, its benefits like social connectivity should not be disregarded. Currently, clinical research on yawning’s connection to relieving symptoms of diseases like multiple sclerosis are in the works. The next time you unintentionally (or intentionally) cause a cascade of yawns within your friend group, remember that they are not mocking you, but rather subconsciously expressing their empathy and forging a stronger social bond.