Yawning is usually considered a harmless occupation but recently a US Man received a six month jail sentence for yawning in court. The prosecutor said that what came out of the defendant’s mouth could hardly be described as a yawn and the Judge agreed.

So, what is a yawn and why do we do it? Unfortunately, although various theories exist no-one is really sure what causes this phenomenon. Despite the fact that yawning is so widespread and contagious very little is known about what causes it in the first place.

Boredom, lack of Oxygen and traits passed down from our forefathers seem to be the main explanations on offer. However, experiments have proved that even these do not seem to be true all of the time.

Although boredom seems to be a popular culprit, research has shown that athletes often yawn before a big event and although they may be experiencing many feelings, boredom is unlikely to be top of their agenda.

Lack of Oxygen such as we experience in a stuffy room is often blamed but tests have shown that increasing the oxygen levels in the room do not guarantee a yawn free environment.

Some scientists believe that yawning is a primitive form of communication but this has never been fully established and remains a theory.

What we do know for sure is that if we see another person yawning sometime within the next few minutes we will usually find ourselves in the same predicament. Reading about yawning, hearing another person yawn and even looking at pictures of people yawning can set us off almost straight away.

When we yawn our heart beats faster, we draw in more oxygen and we open our mouths very wide. Cats, dogs, horses and other animals even fish, also yawn so it is not unique to humans. Research has shown that chimpanzees find yawning as contagious as humans but again there is no clear reason why they yawn.

Trying to stifle a yawn is very difficult and extremely unsatisfying. Sooner or later the temptation is too great and we have to give in. The relief is incredible but does not guarantee immunity as one good yawn often deserves another.

We often place a hand over our mouths when we yawn as this is considered socially acceptable behavior but this does not prevent the spread of this strange affliction. Even though our mouths are covered, our eyes and posture easily give us away.

Next time you yawn, look around and see how many people you have affected. They will be the ones with hands over their mouths, gasping for breath with tears in their eyes.

How many times have you yawned while you have been reading this?