What’s the Deal With Yawning?

By Alyse Borkan  |  Sep 12, 2014
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Remember when Sasha Obama yawned during her dad’s inaugural address, and people thought she was bored or that she’d had a long day? Well, they might have been right, but they also might have been wrong.

The truth is, no one really knows why we yawn. We know what a yawn is: an involuntary, sharp inhalation of air; that they start early: fetuses have been known to yawn; we even know that yawning is one of our most fundamental behaviors: as Darwin pointed out, “seeing a dog & horse & man yawn, makes me feel how all animals are built on one structure.” But we just don’t know why. Yawning, one of the most pervasive human behaviors, is still a total mystery. A lot of really smart people have thought about it over the years, and there are some good working theories out there that make a lot of sense. Here are the three of the more accepted ones.

1. Yawning is a Cooling Mechanism Hippocrates, back in 400 BC, thought that a yawn preceded a fever, because it’s the hot air itself that makes us sick (antiquity was really the hey-day of medical reasoning). It’s like “the large quantities of steam that escape from cauldrons when water boils,” he said. So a yawn, then, is when “the accumulated air in the body is violently expelled through the mouth when the body temperature rises.” But the idea of the yawn as cooling mechanism has been thrown around as recently as 2011. Psychologist Gordon Gallup released a study titled “Yawning and Thermoregulation,” which argued that yawning is a means of, yes, thermoregulation. Pointing to conditions like multiple sclerosis and migraines, which are “linked to thermoregulatory dysfunction” and often are “associated with instances of atypical yawning,” he concludes that yawning is a symptom of “conditions that increase brain and/or core temperature.” It sounds like it could be right, right? But then studies like this come out, which call Gallup out explicitly: “Gallup believes that our recent review on the function of yawning is unbalanced and that it ignores evidence for his thermoregulation hypothesis. Here we address these criticisms and show them to be untenable.” They go on to say that no one really knows why we yawn. Yawning, it seems, is a physiological Bermuda Triangle.

2. Yawning is a Mediator of Behavioral Arousal; or, a Physiological Call to  Perk Up. It might be important to look at when we yawn to figure out why we yawn. We yawn when we wake up, before we go to sleep, before we eat, and when we’re bored (and any time any one else around us yawns, but we’ll get to that in a little). It is then, according to this article in the Journal of Neurology, Neurosurgery, and Psychiatry, “followed by an acceleration of the electroencephalographic rhythms.” This means that after we yawn, our brains are actually more active than they were before the yawn. So when we’re tired, or bored, the “semi-voluntary” act of yawning serves to “increase vigilance… when drowsiness occurs,” as per this article, simply titled “Yawning.” More likely, as Maria Konnikova writes it “may simply signal a change of physiological state a way to help our mind and body transition from one behavioral state to another — ‘sleep to wakefulness, wakefulness to sleep, anxiety to calm, boredom to alertness.’” She’s quoting Robert Provine, a neuroscientist who wrote a book about yawning. So while people report yawning more when they’re tired, it is important to note that the abstract of that article from the Journal of Neurology (etc) starts out by saying that “The precise role of yawning in human physiology remains unclear.” Further, the article, “Yawning,” says that “The aim of yawning is not yet well defined.” Even Provine says that “Yawning may have the dubious distinction of being the least understood, common human behavior.”

3. Yawning is a Mechanism of Social Signalling Everybody knows about contagious yawning. The easiest way to induce a yawn is to be near someone who is already yawning. It doesn’t matter if we are experiencing any of the feelings from the section above or not; we will all almost definitely yawn when we’re wide awake and fully focused on what we’re doing if the person next to us is already doing so. We even yawn when we read about (**insert obvious joke asking reader if he has already yawned**). But why are yawns so contagious? The answer is empathy. Humans (and chimpanzees) are empathetic creatures, so contagious yawning may be our physiological way identifying with each other. And it makes sense in a way, because we’re more likely to catch a yawn from a friend than an acquaintance. We’re also more likely to catch a yawn from someone of the same race than a member of a different one. And this all follows. Kids yawn, starting in the womb as mentioned earlier, but they don’t contagiously yawn until they’re around 7-years-old. Contagious yawning is learned, right around the same time empathy is. Yawning, though, according to Provine, isn’t really about empathy. “We’re getting insight into the human herd,” he says. It’s “a primal form of sociality.” It’s a mechanism of communication then. We tell other people how we feel by yawning, signaling our exhaustion or hunger or whatever. Yawns might not actually be contagious at all, then. It might just be a subconscious reply: an acknowledgement that we understand what’s happening to another person. But really, and we can’t stress this enough, no one know what the deal is with yawning. No one knows.

— Josh Segal 


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