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Why do we Yawn?

I was sat up late the other night deep in interesting conversation, engrossed, not tired and not wanting to be tired, when I was overcome with an attack of the yawns.


Now this isn’t great social etiquette, and I was duly chastised, however I couldn’t understand why it had occurred.


Yawning is associated with fatigue, boredom, group mimicry and 90’s rom-coms, but it’s not to meant to happen when you’re in a conversation and enjoying yourself.


So in an effort to defend my yawning affected social etiquette I went on an interweb based adventure of discovery and exploration to determine the who’s, what’s and wherefor’s of yawning.


And satisfyingly for this yawner I am not not the first to ask the question, from Hippocrates to Darwin to Oliver Sacks the best scientific minds of history have variously written on and bemoaned the act of yawning.

What is a yawn?


It starts in the back of your throat, the muscles of your mouth and neck suck your tongue downwards into the depths of the mouth.


Now this can sometimes lead to a false yawn, the nervous, I have nothing to say in this social situation, where the yawn doesn’t kick in, but you open your mouth and pretend to yawn anyway.


But if it’s a real one, a good one, the bigger muscles of your neck will draw your jaw lower, you’ll begin to intake breath at a normal rate but then your head tilts back and you enter the Full Yawn Zone*.


I haven’t found corroborating evidence of this but I classify the Full Yawn Zone as the bit when your head goes back, the muscles of your neck contract, your eyes squint, your throat echoes with the loud intake of air as your lungs fill.


For some the Full Yawn Zone incorporates arms raised above the head but I do not classify this is a compulsory part of the Full Yawn Zone.


*The Full Yawn Zone is a Errol St Osteo trademarked term.

So why does it occur?


So I went adventuring through the deep space of the interwebs.


Initially flying through the pages of WebMD, the Mayo Clinic, The Independent UK, How Stuff Works I was a bit disappointed.


They had all been written within 1 year of each other, and they all seemed to quote the same researcher, Dr Gallup of Princeton, and his theory of yawning.


This article by Gallup suggested that yawning was related to body temperature. That when you yawned the vessels in your mouth get cooled down as the air flows over them.


As the believers in yawning-being-a-social queue contend; this argument is flawed.


To elicit a yawn, random people were shown an image of someone yawning. They were recorded as to whether they yawned in response or not. The study was done in winter and summer, at altitude in the USA.


And they found that people yawned more when it was cold.


But, but, but, if yawning was evolutionary useful to cool the brain down, wouldn’t you yawn more when it was bloody hot, and if it was cold, surely you wouldn’t yawn and further freeze your brain.


And this idea of cooling your brain down fails to take into account the very fact that to get someone to yawn you have to show them an image of someone yawning.


This if nothing else shows that yawning has varied causes and meanings.


And besides, when I was yawning, I was in an apartment, with the heater on, I wasn’t even close to being cold.

So What Else Could Cause Yawning?


Charles Darwin observed that as humans, horses and dogs all yawn it made him think that “all animals are built from one structure.”


In 1923 Sir Francis Walshe, a British neurologist, observed that stroke paralysed patients were able to regain their movement reflexes for the duration of time they yawned for.


Both Walshe and Darwin were of the opinion that yawning was decidedly ancient animal activity, that had to be evolutionary useful for the simple fact it had survived in so many species for so long.


But for what purpose?

When do we Yawn?


Scientifically it is known that we yawn when we’re:


Feeling sleepy


In the first hour of being awake



About to do something


Psychology Professor Ronald Baenninger used wristbands to follow the actions of his subjects for 2 weeks and found that people were far more likely to yawn when stimulation is lacking or when stimulation is required.


Athletes are seen to yawn prior to races, skydivers before leaping out of planes, as well as students stuck in 3 hour lectures and fatigued office workers at the end of the day.


But that doesn’t account for the fact that we mimic others that yawn, or at least we do once we reach the age of 4. Babies yawn, a lot, but do not catch a yawn off another.


Or that we are far more likely to catch a yawn from someone that we love/know well, or wish to love/know well, than a random person on the street.


In fact the closer you are to someone, or the closer they are to you, not only will they mimic your yawn, the quicker they will do it.



Yawning is a deeply ancient behaviour of vertebrates. It is used in a physiological as well as social manner.


Physiologically it is useful to fire us up, we do it when we are stagnating or prior to a big event in which we will need energy.


Socially, yawning is a primordial way of showing closeness to someone, of fitting in within a social group.


If you wished to test how close you are with someone, yawn, check if they reciprocate, and how long did it take for them to yawn back.


If they don’t yawn back… make new plans.

Errol St Osteo: Apologises To All Those That Yawned in the Reading of this Post.

Posted in : How the Body Works
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