Did You Know? Yawning is a contagious action

You must have noticed how whenever the person next to you yawns, you always yawn too. Even reading this question will automatically make you yawn! Why? Yawning is an involuntary action that causes us to open our mouths wide and inhale deeply - for as long as six seconds. How can you tell that it's involuntary? Well, because research shows that even 11-week-old foetuses yawn! When you yawn, your body is not at rest, nor is it inert in any way. First of all, your mouth opens and your jaw drops so that you can inhale as deeply and as much as possible. And when that happens, your lungs expand naturally, and some of the air is then expelled back through your mouth. Your heart rate can rise up to 30 per cent during a yawn.

Most people feel that yawning is caused when you are fatigued, drowsy or bored, but there is more to this than meets the eye. For instance, researchers have suggested that our bodies can sometimes induce yawning to help draw in more oxygen or to remove an excess of carbon dioxide. Some research shows that yawning is something that began with our ancestors, who used yawning to show their teeth and intimidate others. And still others have proved that since all mammals yawn from cats and dogs to fish - it may just be an involuntary action.

Yet another theory says that yawning is a protective reflex to redistribute the oil-like substance called surfactant that keeps the lungs lubricated and keeps them from collapsing. So, if we didn't yawn, according to this theory, taking a deep breath would become harder and harder.

While it's true that humans have been yawning for as long as they have existed, we still don't have a concrete clue as to why we do it!