Keep your brain cool by yawning

For many years yawning has been associated with sleepiness and boredom, and with low oxygen levels in the blood.

The brain burns up to a third of the calories we consume, and as a consequence generates a lot of heat. The brain operates more efficiently when cool and yawning enhances its functioning by increasing blood flow and drawing in cooler air, reported by Andrew Gallup, a psychology professor at the State University of New York at Albany.

The study may also help explain why yawning spreads from person to person.
A cooler brain, Gallup said, is a clearer brain.
So yawning actually appears to be a way to stay more alert. And contagious yawning, he said, may have evolved to help groups remain vigilant against danger.

Some interesting facts : An average yawn lasts about six seconds. The heart rate can rise as much as 30% during a yawn. Nearly 55% of people will yawn within five minutes of seeing someone else yawn. Blind people yawn more after hearing an audio tape of people yawning.