Yaaaawwwwwn. Chances are just reading that was enough to encourage an involuntary response from some of you: another yawn. And what’s that now across the room, a yawning friend? And so goes the merciless spread of a wild yawn, enigmatic and irresistible. But why? As connoisseurs of all things sleep, those of us at Sleep Outfitters were determined to find out. But only after a quick yawn ourselves.
Though permanently associated with rest or the lack thereof, for many the very purpose of a yawn remains elusive or at least falls under the category in your mind labeled, “To Google at a Later Time.” Why do we yawn? Fear not: you are in good company, as this very question has plagued the scientific community for as long as there has been a community of scientists. And admittedly, not much academic effort has been exerted on this particular topic. "This is of interest, but it’s not something that is going to save human lives," said Daniel Barone, a sleep expert at Weill Cornell Medicine and New York-Presbyterian, to The Washington Post, explaining why yawns don’t get as much research attention. There are, of course, many theories (around 20 physiological reasons have been proposed by scholars, in fact), but no real consensus on the exact reason we spend so much time squinting our eyes, stretching out our jaws, and breathing in deeply and irrepressibly. So, here’s what we think we know.
It’s not tied to oxygen. Contrary to popular belief, it seems we don’t yawn to draw more oxygen to our lungs and blood. This felt like a common sense solution, as yawns tend to pull in a lot of air at once and we tend to do it most when we are tired. But more recent evidence points away from this explanation. And think about it: do you find yourself yawning much as you exercise? This would presumably be when you needed oxygen the most, and yet studies show the levels don’t change.
It’s ancient and not exclusive to humans. If you haven’t spent much time considering the nature of yawning, it’s probably because it feels like it’s just always been there. Most of us begin spontaneously yawning in the womb as early as the second trimester, but it’s even more deeply embedded than that, stemming from so deep in the brain that it doesn’t even really qualify as reflex. “It’s often said that behavior doesn’t leave fossils, but with yawning, you are looking at a behavioral fossil,” says Robert Provine, a neuroscientist and the author of Curious Behavior: Yawning, Laughing, Hiccupping, and Beyond. “You’re getting an insight into how all of behavior once was.” It is unconscious and passed down from early evolution, perhaps long detached from its original purpose but not doing enough harm to disappear altogether from our code.
And it’s not just people, it’s much of the animal kingdom. Snakes realign their jaws after a feast with a yawn, guinea pigs do it to communicate anger, and penguins incorporate it into their mating routines. Even fish do it! “Seeing a dog and horse and man yawn makes me feel how much all animals are built on one structure,” noted Charles Darwin himself way back in 1838, and it seems little has changed in centuries since.
It’s likely linked to keeping cool. Believe it or not, yawning could simply be a method of keeping your brain cool, acting as Smithsonian Magazine puts it almost as a radiator. It might not be surprising to learn with all our brains are responsible for that things can get heated, which they naturally try to avoid. A yawn increases our heartrate, blood flow and use of facial muscles, all vital to regulating brain temperature.This would also explain why we yawn the most when worn down, as exhaustion and sleep deprivation can heat up the brain. “Before we fall asleep, our brain and body temperatures are at their highest point during the course of our circadian rhythm,” says Andrew Gallup, a psychology professor at SUNY College at Oneonta, which yawning can help offset. “Once we wake up, our brain and body temperatures are rising more rapidly than at any other point during the day.” A recent study by Gallup saw participants placing warm and cold packs on their heads. While watching others yawn, 41 percent yawned with the warm pack, while only nine percent did with a cold pack. The correlation was clear.
It is contagious. But don’t bother covering your mouth; seeing others’ yawning eyes, reading the word “yawn,” or even thinking about the act is enough to catch one yourself, as numerous studies have shown. Many scholars have linked this to empathy, or the ability to understand and share the feelings of others. Children aren’t as susceptible to contagious yawning until ages four to five, which expectedly is also when they develop empathetic behavior. Likewise, studies have found those diagnosed with autism yawned significantly less than their peers, picking up on less empathetic social cues. This is all understood to relate to mirror neurons, brain cells that are used for learning, self-awareness, and relating to others. They fire when we perform an action, see someone else perform that action, or even think about the action.
Interestingly, this leads to a phenomenon where we’re more likely to mirror the yawn of someone socially or genetically close to ourselves than a stranger, implying a social, communicative aspect of yawning. Many have speculated yawning is a mechanism for signaling to others a changing state, whether it be from calm to anxious, from tired to alert, or from activity to rest, and encouraging others to share the experience, potentially for survival.
Whether it’s about keeping the brain running at full capacity or relating better with friends and family, one thing most seem to agree on is yawning is an enjoyable quirk. And if that yawn leads to rest, well, Sleep Outfitters has just the solution for you.