Ever Wondered why we yawn?

Ending off a 10-hour workday just as you glance up to check the time, you are hit by a long yawn and that's when the realisation kicks in that you have tired your body working. But it's not just us humans. Birds do it, dogs do it, and even a foetus in the womb yawn. But why? I'm sure we all know that yawning is a sign of tiredness and one's body is telling to stop working and take some rest. But have you ever wondered what a yawn does? 

The general explanation of a yawn is that it signifies that you are tired. But this is not the significance. There is much more to a yawn than just telling you you are tired. A yawn is actually a cooling mechanism. Just like computers and other machines, as you keep working and tiring yourself, along with the body, the brain also heats up. A yawn is a natural radiator system to cool down the brain by bringing cooler blood to circulate around the brain with the blood acting as a coolant. As time passes this temperature reaches its highest point right before we sleep, hence more frequent yawns. Opening the jaw wide open to accommodate the yawn increases the rate of blood flow to the skull. The other cooling component is the air going into the nasal and oral cavity while inhaling that goes past mucous covered blood vessels. This air changes the temperature of the blood in these vessels that go to the forebrain, the part of the brain that controls processing information, controlling motor functions and so on. This cooler blood not only cools down the brain but also makes you alert and perform activities more effectively. Another non-significant explanation of yawning is that it is a way of exchanging larger amounts of oxygen and carbon dioxide while breathing than usual. 

Now when it comes to yawning the most frequently asked question is why it is contagious and there are two sets of hypotheses to that question, physiological and psychological aspects. First under physiological is the fixed action pattern. This is more like a reflex. Just like how we dodge a bell without thinking, a chain of yawns passes through everyone in a room without them wanting to yawn. The second type is called non-conscious mimicry, or to put it in a simpler form, 'monkey see- monkey do'. Imitating someone's behaviour unconsciously, like crossing your legs when someone crosses their legs, smiling back at someone who smiled at you, etc. This is caused by a set of neurons called mirror neurons, that perform an action uniformly when someone else performs it. Mirror neurons help in activities where you 'watch n learn'. The psychological aspect is related to empathy, yes, empathy. Empathy is the ability to understand what someone is feeling and partake in their emotions. A part of the mirror neurons enables us to empathise with someone. That is why we are more likely to catch a yawn of a known person like friends and family rather than a stranger. It is also observed that kids around the age of 4 tend to have contagious yawns, the same age when children start understanding others emotions.

So next time you're on a yawning spree, remember to cool that brain down;)