What a Yawn! What a Brain!

What is yawning?

According to the Oxford dictionary yawning is “a reflex act of opening ones mouth wide and inhaling deeply due to tiredness or boredom”.

It is a very familiar activity that we all engage in at times, particularly whilst studying, sitting through a boring movie or watching the clock on Friday afternoons anxiously waiting for that last lecture to end or work to finish! For many, yawning is seen as an unpleasant, bad mannered and an embarrassing waste of time; an evolutionary throwback from our ancestral roots that we haven’t yet been able to supplant.  How many times have we found ourselves red faced when an uncontrolled yawn overpowers us during an important social function or whilst listening to a friend describing their latest overseas adventure! Yawning, believe it or not, has a number of useful roles to play in caring for our health – all related to our brain function.

Keeping it cool

In a study conducted in New York in 2007 it was suggested that yawning automatically causes the inhalation of fresh air to cool the brain and preserve cerebral effectiveness, much like a fan is used to cool a computer’s CPU. This action is known as the thermoregulatory theory of yawning and is important in maintaining our body’s homeostasis. It is proposed that this mechanism would come in to play when the brain temperature increases due to complex brain processing. That is, increased yawning would occur resulting in cooling the brain.

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Cooling our brains like a CPU. Image credit: bengt-re (Flickr)

Waking up

Yawning on waking up in the morning is a good response to have before we grab a coffee as it has a positive effect on our brain. When the physical process of yawning takes place it results the automated masseteric reflex of the jaw activating brain activity. When we are at rest or in a contemplative mood our brain enters a neutral or similar to a computer sleep mode. However, during this time a default mode network (DMN) maintains core brain activity. Yawning appears to unlock the DMN and put the brain back into gear. It does this by stimulating the locus coeruleus, which acts to boost brain alertness.

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Burning the midnight oil: yawning to stay awake. Image credit: English106 (Flickr)

Egg heads rule

There has been recent studies into comparing yawning behaviours in humans and other mammals. Primates such as gorillas share many of the yawning habits as humans. A study in New York in 2016 examined a large sample of mammals that were recorded yawning on YouTube and compared the yawns. The study found that the length of time that an animal yawns is a good predictor of its brain size and complexity; primates were observed on average to have longer yawn patterns than other mammals such as dogs and cats.

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Look at the yawn on this gorilla. Image credit: myopixia (Flickr)

Humans yawn for longer periods of time than other mammals and the study suggests that this is because human brains are larger and significantly more complex. In fact it is thought that the physiological impacts of yawning have an effect on the brain as a whole and can be used to stimulate the brain’s activity.

So I’m not being lazy when I yawn, I’m just exercising my brain.


5 Responses to “What a Yawn! What a Brain!”

  1. dohertya says:

    Jessica and Claire – Very interesting point, I was actually wondering the same thing when writing this post but decided not to make it too complicated. A 2014 study (https://www.eurekalert.org/pub_releases/2010-09/sfri-cu4090810.php) examined several factors that have previously been linked to ‘contagious yawning’ (as compared to ‘spontaneous yawning’) and could not find any significant associations. However, they did report that contagious yawning may be linked to age. They also debunked the theory that contagious yawning is linked to empathy. Although, further study is definitely needed in this area – most studies have very vague conclusions!
    Interestingly, another study suggested that children with autism are less likely to be subject to contagious yawning and they concluded, like Dr Karl, that this phenomenon was related to empathy (https://www.eurekalert.org/pub_releases/2010-09/sfri-cu4090810.php). I’ll stop there as this comment is turning into a mini essay.

    Tal – Chimpanzees can apparently ‘catch’ yawns! Current research suggests that ‘contagious yawns’ are unique to humans and chimps.

    Tim – I’ve heard this too, I think it is a common theory. I did read an article claiming that yawning to get more oxygen to the brain is actually a myth (http://www.smithsonianmag.com/science-nature/why-do-we-yawn-and-why-is-it-contagious-3749674/?no-ist).

  2. Timothy Brown says:

    Interesting post! Loved the title. I’ve been told yawning occurs when we aren’t getting enough oxygen to our brain – when we are tired and concentrating and don’t breathe enough. Did you read anything about this? (I’ve haven’t researched it at all so it might be completely wrong)

  3. Tal Cohen says:

    Was thinking the same thing as Jessica.
    I guess increased brain size/complexity COULD correlate with increased sociability of a species (and thus contagiousness). Do you know if primates also ‘catch’ yawns?

  4. Claire MacGregor says:

    Great post! I always seem to fall victim to the old “contagious” yawn. I heard something Dr Karl was saying that when we catch a contagious yawn its because we are expressing empathy toward the person who yawned.

  5. Jessica Kamar says:

    Great read, thanks for sharing!
    I wonder how the “contagious” nature of yawning fits in with this? I’ve heard it has something to do with our brain notices another person yawning, and it is reminded that it might be a good thing to do… seems like quite a simplistic idea, but very interesting when trying to fit into the overall evolutionary picture.