Common mysteries: case file #001 - are yawns actually contagious?

Art by Zazie Pritchett-Sidle

Case Opened: September 2025 

Subject: The Curious Contagion of the Yawn 

Setting the Scene

You’re in class, sleepy and bored. The person in the seat next to you stretches, letting out a long yawn. Within the next seconds, three more of your classmates follow. By the end of the lesson, it seems that the entire class has caught it. 

Coincidence? Hardly. Our case today investigates the strange social domino effect of the contagious yawn. 

Exhibit A: The Anatomy of a Yawn 

A yawn is absolutely more than just a sign of boredom or fatigue, it's actually a full body, biological reflex. On a basic scale, you’re essentially taking a giant gulp of air and powerfully stretching the muscles around your mouth and throat. Then, you rapidly exhale and let all that air out (Cleveland Clinic). This reaction is almost involuntary, though you can induce it by, you guessed it- seeing other people yawn.  

Exhibit B: The Evidence for Contagion 

Scientists often distinguish between spontaneous yawns (when you’re tired or bored) and contagious yawns (triggered by seeing, hearing, or even thinking about yawning)- a distinction confirmed in Bartholomew & Cirulli’s 2014 study (you can find it here). The evidence is clear: yawns do spread. In one study, subjects were six times more likely to yawn after seeing someone else do it, as compared to a neutral face or on their own (PBS). Weird, right? Well, this strange thing isn’t a reflex that's unique to us as humans. 

Lots of different animals, including elephants, dogs, chimpanzees, and even birds also yawn. It’s also on an inter-species contagion level- as pet owners also report yawning when their pet does, and vice versa (PMC). This little detail makes scientists think that yawning isn’t just there for fun, but that it served some sort of evolutionary purpose. So what would that purpose be? 

Exhibit C: Possible Theories 

Well, the short answer is that we don’t know for sure. The case isn’t closed, but here are some leading suspects. 

Empathy and Social Bonding: One function for the yawn could be this sort of unconscious mimicry, reflecting our ability to feel what others feel. It’s akin to facial mimicry, like laughing/smiling when you see someone else do it (Frontiers).

Group Vigilance: Some researchers believe that yawning could spread synchronicity and alertness in groups, when a big evolutionary advantage was how watchful you were. This action could get a big group to pay attention to the same thing (science.org). 

Brain Cooling: One physiological hypothesis for yawning suggests that yawning helps to regulate your brain temperature. On a basic level, seeing someone else yawn could signal to your brain that you could need a cool down (Cleveland Clinic). 

Case note: Each of these theories has evidence, but none of them fully explain the phenomenon. Like a real suspect lineup, the answer could be one, none, or even a combination. 

Exhibit D: Unsolved Clues 

Apparently, not everyone is susceptible. Depending on the study (the numbers vary), only 30-60% of people yawn contagiously when exposed to videos or in person stimulation (Utrecht University). And while empathy does seem linked, the connection isn’t really consistent across studies. Some find a very strong tie, while others find somehow little to none (Science Direct). Essentially this is because measuring empathy itself is very tricky, but science does its best. 

Case note: The jury is still out. Contagious yawning is real, but the question of why remains an open case. 

Case Closed (For Now)

So yes- yawns are contagious. But the reason for your yawning in class while reading this article may have more to do with empathy, attention, or evolutionary survival than just being bored with the lesson. Next time you catch a yawn, think of it as joining a very old club- a reflex that you can relate to across species, time, and very countless sleepy classrooms. 

Filed under: Social Mysteries, Ongoing Investigation