Many parts of the body are in action whenever you yawn. First your mouth opens and your jaw drops allowing as much air as possible to be taken in. When you inhale the air taken in is filling your lungs. Your abdominal muscles flex, and your diaphragm is pushed down. The air you breathe in expands the lungs to capacity and then some of the air is blown back out.

Many people yawn more at bedtime or whenever we wake up and also when we’re bored. Some people even yawn in their sleep.

But sometimes people don’t yawn whenever there tired or bored for example some paratroopers yawn before their first jump, some violinists before they go on stage and some Olympic athletes before their big events.

Many people believe that yawning gets more oxygen into the body or release carbon dioxide. So yawning helps us by bringing more oxygen into the blood and move more carbon dioxide out of the blood. But this statement is not true. The truth is nobody really knows why we yawn, Guesses have been made but nobody is sure why.

It has been said that yawning helps to cool our brain down. They say yawning increases blood flow to the brain which moves the heat away from it acting lie a radiator. They also say yawning may also be stretching muscles since yawning sets off an urge to stretch.

A study led by Andrew Gallup, a postdoctoral research associate says that yawning frequency varies with the season and that people are less likely to yawn when the heat outdoors exceeds body temperature.

It's known that yawns are contagious. Just by reading or listening about them you're more than likely to start yawning. The yawn could be a social signal to stay alert even though things are boring at the moment. The yawn might help to increase alertness or it could just be a way of signaling to others that we're relaxed in stressful situations.

Some researchers have found that you could stop the yawning by breathing through your nose or applying cool cloths to your forehead, they also found that we could stop yawning by taking a cold shower or swimming in cold water.

They found that excessive yawning can be caused by a vasovagal reaction. This reaction is caused by the action of a nerve, called the vagus nerve, on the blood vessels that may indicate a heart problem.

The reaction is caused by the action of a nerve, appropriately called the vagus nerve, on the blood vessels. Vasovagal reaction is commonly associated with heart problems and could be very serious.