Yawning acts to cool the brain, according to a new study.
Researchers recorded yawning habits of people in Vienna, Austria and Arizona, in the United States, during the winter and summer months. They found people in Arizona yawned more in winter than in summer, and the opposite occurred in Vienna, where yawning increased in summer.
They say yawning is not related to the seasons but occurs due to atmospheric temperature. People stopped yawning when surrounding temperatures reached around body temperature because the cooling function was no longer needed.
Read more at University of Vienna