“How yawning could help cool down your brain” in the Atlanta Journal Constitution reports that researchers at the University of Vienna have found that the amount of yawning we do increases when our brains are hot.
This was reported in the Daily Mail in London: “Yawning? It must be 20C (68F) [exclamation mark removed] Humans yawn to cool their brains as it boosts mental ability.”
These yawns not caused by boredom but by temperature?: