Is yawning really contagious?
Bet you can’t get through this article without ripping out a yawn. That’s because yawning is, in fact, contagious. “One thing that’s clear is that yawning is extremely contagious. So much so that everything having to do with it–thinking about it, hearing it, reading about it, seeing someone do it–triggers contagion,” says Robert R. Provine, neuroscientist and professor of psychology at the University of Maryland, Baltimore County and author of Curious Behavior: Yawning, Laughing, Hiccupping, and Beyond.
According to Provine, 55% of people thinking of yawning will do so within five minutes. And contagious yawning is shared across species–all vertebrates yawn, he says. (One just-for-fun example? This study looked at the phenomenon in sheep.) So, what’s going on to make it so catchable?
“Yawning is one of the first behaviors to develop. In a fetus, it shows up about 11 weeks after conception,” says Provine. While people yawn at birth, yawning contagion doesn’t appear until several years later, he says. Ultimately, that timeline suggests we evolved to yawn in groups.
So, while catching someone’s yawn might be a fun trick, yawning that triggers a ripple effect may serve the primal purpose of synchronizing behaviors in a group, like bedtime, says Provine. (In addition to the bedtime benefit, yawning after someone else even makes you seem trustworthy, research says.) Because yawning happens during transitions–waking up from sleep, before going to sleep, or going from alert to bored–it may also “help us shift physiological gears,” he says.
Not everyone agrees that yawning is contagious, however. In a 2017 study in Adaptive Human Behavior and Physiology, an experimental psychologist at the University of Oxford, Rohan Kapitány, wanted to put that belief to the test. He didn’t ask why is yawning contagious. Instead, he asked: What if yawning isn’t actually contagious?
After reviewing the literature and conducting his own experiment on a group of college students, Kapitány concluded that one person’s yawn could not reliably make another person yawn. In other words, there didn’t seem to be a causal relationship between the two. It only seems as if you “caught” the yawn, when in reality, it was merely coincidental, he says. And, he asks that we put our own experience with yawns aside–which is a big request. Because, well, have you yawned yet?
Check out these other surprising things you didn’t know were contagious (restaurant orders, anyone?).