Once it onsets, it’s difficult to stop. You open your mouth, extend your jaw, and inhale for 3-6 seconds; your eyes are closed and you might even stretch out your arms and neck. You exhale with a satisfactory sigh, and your eyes water up a little. Congratulations, you’ve just yawned!

In this blog we’ll explore yawning: what it is, why it happens, and what scientists know about it (as well as some fun facts of course).

Yawning is a very peculiar thing, it’s an involuntary physical action that your body initiates; it’s tough to explain why we do it. Similar to laughing, hiccupping, or even sneezing, yawning appears to come out of the blue, sometimes at the most inopportune times.

What happens when you yawn?

The large breath you take when you yawn fills your lungs with air; as you open your mouth wide and your trachea fully opens, air more easily flows all the way down to your diaphragm. Your heart rate briefly increases briefly when you yawn, and your head will usually tilt back (perfect opportunity for your friends to stick things in your mouth).

Your eyes will typically close shut and you may hear a rumbling sound. That’s the sound of your tensor tympani, a muscle in your ear canal that protects your eardrum from loud noises, contracting as your jaw fully opens. It’s not uncommon for your ears to “pop” as the airflow induced by your expanding jaw is likely to bring the air pressure in your ears in equilibrium with your surroundings.

You may find yourself stretching out your neck, arms, and back — an action called pandiculation. Let’s be honest, there’s really nothing better than a deep, uninterrupted yawn coupled with an amazing stretch (even better after sitting in the car for too long).

If you’re like me, you’re probably holding back a yawn right now after reading about them. This is actually a studied phenomena that we’ll look at in a bit!

So what kinds of things yawn anyway?

Yawning begins at an early age. Believe it or not, babies in the womb begin yawning after as little as 20 weeks after gestation! That’s when they’re just the size of a mango!

Yawning isn’t just unique to humans though, most animals have been known to yawn. Below is a picture of some animals yawning! From mammals to birds to fish, pretty much anything with a mouth has been observed yawning. Apparently giraffes don’t yawn though, although the jury’s not out on that one.

If you’re interested in seeing fish yawns, check out this article by Mark Fuller, a marine photographer who is obsessed with fish yawning!

You ever see someone yawn, or think about yawning, triggering your own yawn? We’ve all been there. Even worse, you and a friend have a continuous, never-ending loop of contagious yawns.

Ever notice your dog catching yawns from you? Believe it or not, only dogs, dog relatives (wolves), certain primates, and humans have been documented to catch contagious yawns! Maybe that’s why dogs are man’s best friend, they can relate to us.

Let’s make a distinction between yawns: spontaneous yawns and contagious yawns.

Spontaneous Yawning

Spontaneous yawning is when you yawn alone, independently of thinking about yawning, seeing someone yawn, or any other trigger.

One theory as to why we spontaneously yawn is to transition the brain into a more attentive or less attentive state. As previously mentioned, when you yawn, your increased heart rate and deep breath will rush oxygen to your brain, giving it more fuel to operate.

Spontaneous yawning tends to occur before and after your usual sleep time. It is also more likely to occur if you are feeling fatigued or tired. It’s like your brain’s internal way of telling you to go to bed!

Yawning may also function as a cooling mechanism for the brain. As you open your jaw, blood circulates in and around your ears, which are pumping air into and out of your ear canal. Think of it like a radiator forcing hot water through a surface with high air flow to cool the water down.

Spontaneous yawning can also be a sign of nervousness, in fact it’s not uncommon to see athletes yawn before competitions, and even paratroopers have been known to yawn before jumping out of planes. This further reinforces the idea that yawning is your body preparing for some sort of mental transition. Funny enough, a 2015 leaked TSA document listed 92 “stress factors” that could be signs a suspicious person, one of them: exaggerated yawning.

Contagious Yawning

Contagious yawning is just the opposite of a spontaneous yawn: an external factor triggers you to yawn.

Turns out seeing someone yawn, hearing a yawn, and even thinking about yawning can trigger a contagious yawn.

This kind of yawning is a prime example of positive feedback, a process in which the factors that cause a change in the environment are then produced more strongly by the environment as it changes, exacerbating the change.

An example of positive feedback is audio feedback. Take a microphone for example: small perturbations in the microphone electrical systems can cause a small amount of noise, this small noise then gets amplified by the microphone to be a little louder. The keeps looping over and over (over the course of less than a second), and the microphone makes a loud screeching sound. Positive feedback by itself is unstable, that is, left unchecked it will overwhelm a system to the point of no return.

Although no one is really sure why contagious yawning occurs, some scientists suggests that it may be a form subtle communication among a herd or group of animals. If I start yawning, and it spreads to all the students in the college lecture I’m in, it’s a good sign to the professor that the lecture is boring! Similarly if one wolf starts yawning and all the wolves start yawning, maybe it’s a collective way of saying “bedtime.”

Contagious yawning does however seemed to be linked to age and emotional connection. In one 2013 Swedish study, dogs were shown to only “catch” yawns from other dogs at around 7 months of age. Another 2014 study showed that about 8% of contagious yawning variation was due to age, particularly older individuals had a tendency to catch contagious yawns with a lower frequency. Another 2007 paper published by the Royal Society found that individuals with certain disorders such as autism and schizophrenia were less likely to catch contagious yawns as well.

One of the most interesting facts I came across is that dogs are the only animals found to catch yawns from humans, and it’s 5x more likely to occur if you’re the dogs owner! Could this be because dogs have been domesticated for so long? Could this be the reason why humans initially chose to domesticate wolves? Guess we’ll never know.

If you’re skeptical that you’re susceptible to contagious yawning, click here to see a video that CollegeHumor put out a few years back.

Opinions on Yawning

Throughout the centuries people have had hard takes on yawning, let’s look at a few of them:

Hippocrates (400 BC): “Yawning precedes a fever, because the large quantity of air that has accumulated ascends all at once, lifting with the action of a lever and opening the mouth; in this manner the air can exit with ease. Like the large quantities of steam that escape from cauldrons when water boils, the accumulated air in the body is violently expelled through the mouth when the body temperature rises.”

George Washington (1748 AD): “If You Cough, Sneeze, Sigh, or Yawn, do it not Loud but Privately; and Speak not in your Yawning, but put Your handkerchief or Hand before your face and turn aside.”

Mason Cooley (1927 AD) “A yawn is more disconcerting than a contradiction.”

More Yawning Fun

Did you ever stop to think that the word yawn is used as a verb and a noun? The full list of synonyms to the verb yawn according to Thesaurus.com are: divide, doze, drowse, expand, gap, gape, give, nap, part, sleep, snooze, spread, yaw, yawp, and fatigue catch flies. Some of them sound like a bit of a stretch, the best description of “fatigue catch flies” I could find online was from Urban Dictionary.

For those of you that don’t know your Pokemon very well, yawn is also an attack introduced in Gen 3 (spammed by Norman’s Slaking) that puts you to sleep after 1 turn. The Gen 3 description was technically: “Lulls the foe into yawning, then sleeping the next turn.”

Maybe some of you remember Sasha Obama’s infamous yawn during President Obama’s inaugural address! Hopefully that moment won’t follow her too far into her adult life, quite a thing to be known for.

There was also that hilarious viral video that came out a few years back of the college student yawning during a Cornell lecture and the professor going on a tirade (great watch, highly recommend).

Ok, at this point we’re not learning about yawns, we’re just having fun with them. We hoped you learned something about yawns, drop a comment with your favorite yawning story!