Yawning: a brain-cooling mechanism

Two researchers at the University of Albany have found that

In fact, yawning was found to serve as a brain-cooling mechanism. In the course of the day, our brain heats up as it burns as much as third of all the calories we consume. In order to function more efficiently, the brain needs to be cooled down. Thus when a person yawns he or she instinctively increases blood flow bringing cool air.

Contrary to popular belief, yawning doesn't imply that a person wants to sleep - it may only eliminate the urge to sleep. Researchers also explained the phenomenon of the "contagious yawning" saying that we tend to yawn looking at other person yawning because it draws our attention and this helps the group to stay aware of signs of danger.

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