Yawning: Fact vs Fiction

I was recently at a pond exhibit with a bunch of children.  A cat fish was swimming near the glass and opened his mouth real wide.  A small child next to me exclaimed “fish yawn” “fish tired”.  This got me thinking, do fish yawn?

If you are giving a lecture or teaching a class and the audience begins to yawn, should you be offended?  Are you really that boring?

What does yawning actually mean and why do we do it?  Here are some facts that we know about yawning, however, there is a lot about yawning that is still unknown.


  • People on average yawn 8 times per day.
  • People yawn more in cooler weather.
  • People yawn when they are tired.
  • People yawn when they wake up.
  • People yawn when the room temperature changes.
  • People yawn when they are bored.
  • People yawn when they are anxious.
  • People yawn when they are hungry.
  • People yawn when they start a new activity or enter a difficult situation. (Stress)
  • Yawning is contagious.
  • There is no identifiable physical reason why we yawn.


People with Parkinson’s disease don’t yawn as much as others.  This could be attributed to low dopamine levels associated with the disease.  Dopamine replacement increases yawning.

Cortisol, the stress hormone that is released from your adrenal gland does effect yawning.  If your adrenal gland is removed you stop yawning.

People with autism do not find themselves yawning in response to other yawns as easily as most of us.

All vertebrates yawn.  A vertebrate is an animal with a spinal column.  This includes mammals, birds, reptiles and fish.  So, yes, you have seen your dog or cat yawn.  Their yawns can also be triggered by your yawn and vice versa.  So, that new sleep puppy you just got yawns and now you are yawning too.

In fact, yawning is so suggestable that you may be yawning just by reading this article.

From this list you can see that yawning can be triggerd by a number of things and circumstances.  Even not feeling well can cause you to yawn.  People running a fever yawn more than those who are not ill.


What We Don’t Know:

Since data can be collected on when we yawn and influencers to yawning behavior but there is no real cut and dried reason why we yawn.  There are three main theories on why we yawn.

Oxygenation Hypothesis

This is the theory that we yawn in order to take in a large amount of air in order to increase oxygen in response to oxygen deprivation.  (This one seems to make the most sense to me, but it is no longer in favor as being valid)

Brain Cooling Hypothesis

This theory promoted by Andrew Gallup is that a deep inhalation increases blood flow to the skull which can then cool the brain and promote alertness.  This theory promotes the idea of a physiological cause and physical benefit.  Yawns help regulate the temperature of the body and the brain.

Social Benefit Hypothesis

This theory is based on yawning being related to empathy, stress and social groups.  Humans are meant to live in community like many species.  We know yawning is contagious and could be a form of communication that has social benefits.  The involuntary mimicry of yawning could be a bonding agent between individuals. Yawning also might help wake you up and help you stay alert in times of danger to you or your community.



So, while there is no clear proof for why we yawn.  We do yawn and it isn’t an insult or we wouldn’t all start yawning the minute we see someone else yawn.




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