President Barack Obama trying to hide a yawn - we've seen you Prez. / Getty
Is it really contagious? Or are you just bored? Dr. Nick Knight provides us with three theories behind yawning

It’s one of life’s great mysteries – why do we yawn? What is it that compels us to slowly open our mouths nice and wide, fill our lungs and release...

Majority opinion suggests that yawning happens at our sleepiest and laziest moments. We’ve all been there - caught trying to hold in a yawn during a dull meeting at work, and predictably failing. Studies even show evidence of an 11 week-old foetus – which is just 1.5 inches long – yawning in the womb. But, Dr Nick Knight believes yawning is a more complex reflex than it being based simply on tiredness or boredom.

He takes us through the three most popular theories behind the involuntary action, which include a build-up of carbon dioxide in the body, yawning as an attempt to increase our alertness, and even how the humble yawn could act as an engine cooler for our overheated brains.

And yes, we delve into the process behind that blasted contagious yawn: why do we feel the need to yawn when we see someone doing so? And why can't we stop it from happening?

Watch the video below – we promise you it won’t leave you yawning… maybe.

Gif from Giphy