Ever wonder why... you yawn?

Yawning is a reflex, a subconscious deep inhalation of air through an open mouth, that happens when we are tired, under-stimulated – or when we see someone else do it.

There are several theories as to why we yawn and why it is seen as contagious.

Some researchers believe it works as a brain ‘reboot’ – that the intake of oxygen with a deep breath makes the brain more alert and focused.

The reason why humans, and many other pack animals, begin to yawn when others around them do would then be to ensure that the entire group are at the same level of attention and awakeness.

An 2014 Austrian study has a different theory, suggesting that we yawn in order to cool the brain down, in the same way that a fan cools a stationary computer.

Researchers studied frequency of yawning at different temperatures and found that a yawn helps to regulate brain temperature.