Why humans yawn?

Yawning is a contagious process which is common in both human beings and animals. Usually, we yawn when we are feeling sleepy, tired, bore and see people around us yawning. But no one knows the exact reason for yawning. However, several scientists have carried out some experiments to know what is the scientific reason behind yawning.

A group of researchers from the University of Washington, earlier said that our body yawns to take more oxygen and to release carbon dioxide. Citing this reason, the researchers explained that larger the group of people in a room, more the people yawn. This is because many people would produce more carbon dioxide in a room and everyone will induce to draw in more oxygen, and ultimately, they start yawning.

But this theory has been proved wrong by Robert Provine of the University of Maryland stating that if our body intend to yawn while we need oxygen then we would have yawn more during exercise.

He also tested the above theory and found that presence of additional oxygen is also unable to prevent the people from yawning.

In 2007, another group of researchers has said that the people actually yawn to reduce their brain temperature and to think more clearly.

The human brain is also like a computer which has an optimal working temperature. When the brain gets very hot the people yawn to cool it down. Besides cooling down the brain, yawning helps in increasing both the heart rate and blood flow. Yawning helps in supplying large quantity of air to the head and reduce the brain temperature.

When we are feeling sleepy or get tired we yawn frequently, it is because in such situation brain becomes hot and yawning helps in regulating the temperature.