Ask A Scientist

Why is yawning contagious? 

Asked by: Maggie Lynch
School: West Middle School, Binghamton School District
Grade: 7

Answer from Aleksey Morozov

Graduate Student, Binghamton University

Title: Graduate Student, Binghamton University
Department: Biological Science
Research area: Microbiology (persister cells)
Interests/hobbies: SCUBA diving, hiking, reading and microphilanthropy

Have you ever seen a friend, a relative, or even a stranger yawn and moments later felt an urge to yawn, as well? What causes this contagious behavior? Before we get to that, let us see why we yawn in the first place. Yawning is an automatic response that causes us to draw air deep into our lungs. It often occurs due to stress, boredom, or relaxation. Some scientists have suggested that yawning is triggered by the need to draw more oxygen into our lungs and to remove excess carbon dioxide. This is the reason why you are more likely to yawn after strenuous exercise or in a crowded room.

Other scientists believe that yawning works as a cooling system for our brain. Cooler temperatures allow our brains to work more efficiently and to stay alert. Researchers have demonstrated that people will yawn more often when a warm towel is pressed to the head, than if a cold towel is used.

Yet, these theories fail to explain why yawns pass from one person to another, or why even reading about yawning can elicit the response.

Recent studies have demonstrated that empathy – our ability to understand the feelings of others – may play a role in contagious yawning. Brain imaging studies show that yawning activates the same regions of the brain, as do feelings of empathy. If you observe a stressed or anxious friend yawn, empathy for your friend may cause you to yawn. What this behavior achieves is unknown. Is yawning a way of asking for help? Does one person’s yawn in response to another person’s yawn strengthen the relationship? What is known is that yawning is not limited to humans; chimpanzees, baboons, dogs, and even fish have been observed to yawn. Perhaps yawning served to guide social behavior at some point in evolutionary history. Today, at least in humans, yawning may be just a useless quirk of our biology.

Last Updated: 3/1/17