It seems like a simple question, doesn’t it? Though, the answer is a lot harder to define.
No one is sure why we yawn, we kind of just… do. However, there are several theories on why we do it.
The first theory is that it’s to intake a greater amount of oxygen. Often, we yawn when we are tired, which is when our intake of oxygen lowers (not too life-threatening amounts, of course. The intake is just slower and shallower, which allows us to sleep). Seeing as yawning allows us to breathe in more oxygen, the theory states that because when we are tired or “sleepy” we intake less oxygen, we yawn to make up for it.
However, MuscHealth argues that due to “research by putting people in low-oxygen or high- carbon-dioxide environments” it is unlikely that intake of oxygen is the main reason for us to yawn.
The second theory appears quite easy: it’s simply to keep us awake.
In short, this theory accounts for yawning not being a stimulus-response (an action made in response to another action of the brain) but rather is a stimulus itself. The body will yawn, which in turn attempts to keep us awake and alert by intaking oxygen and stretching the neck muscles. MuscHealth puts it as such: “almost paradoxically, it is theorized that yawning is not a sign of sleepiness or boredom, but actually a reflex that your brain induces to wake you up or make you more alert.” Also, yawning is closely linked to hormones that “briefly increase the heart rate and alertness.” This all points to yawning being a stimulus made to keep us awake.
It’s important to mention that other as to why we yawn is to level out the pressure in our heads (if you’ve ever yawned while a plane was taking off, you know what I’m talking about) and that yawning is also a reaction to what we call social empathy. Seeing someone yawn, or reading about it (like you’re doing right now!) probably will lead you to yawning yourself. Social empathy indicates that the closer you are to the person who is yawning (the “yawner” if you will) the more likely you are to yawn.
In conclusion, no one’s really sure why we yawn, but it is an interesting little bit of science to look into. Or read a short article about. Whatever floats your boat.
-Neva
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