Before you start reading this article, quickly grab a pen and a piece of paper. And record the number of times you yawn while reading this. Anything to do with yawning causes you or someone else to yawn. Looking at videos of people yawning, listening to audio tapes of yawning or even reading material on yawning will cause you to yawn. If you did not yawn even once after reading this post email me.

So why do we yawn and why is it contagious?

The current theory is that we yawn when the brain is not getting enough oxygen. In other words when there is an increase in the carbon dioxide level in the blood and oxyen delivery to the brain is less the brain signals our body to yawn so we take a deep breath with mouth wide open and take in a deep breath into our lungs. Hopefully this deep breath will increase the oxygen delivered to the brain.

Upon seeing another person yawn, we will also yawn. And we do this unconsciously.

You might be surprised to know that babies as early as seven weeks after conception also yawn. That`s right – we are yawning even before we are born! By the time we are one to two years we start to experience the “contagiousness” (Is there such a word?) of yawning. Birds yawn, cats, dogs, apes, chimpanzees and even fish yawn.

We yawn when we are feeling sleepy or bored (my favourite – especially in long lectures!) and we yawn soon after waking. Yawning is associated with stretching and if you try to prevent yourself from opening your mouth wide open while yawning, that will not be a “unsatisfying yawn”.

So the question remains – why is yawning contagious?

The current theory to explain why yawning is contagious is that yawning is what is left of a primitive behavior during the evolution of human beings. The theory is that yawning was used to signal aggressiveness but as we became more “civilised” yawning was used to communicate group behavior. For example when a bird flies after seeing a predator, the rest of the flock took to the air even if they did not see a predator. Or when an antelope sees a lion and starts running, the rest of the herd will use it as the signal for danger and run, even if they did not see the lion. So what does yawning signals to the other person when you yawn? That you are bored? That you are sleepy?

A recently published study done in Finland to answer the question of whey yawning is contagious was inconclusive. It just confirmed what is already know about yawning.

What exactly happens in the brain when we see someone yawn that causes us to yawn remains a medical mystery.

YYAAAWWWNNNN!!! Heck! I forgot the number of times I yawned while writing this.

How many times did you yawn?