Study: People yawn more in winter

September 21, 2011

Yawning isn't just a sign of fatigue or boredom, it's the body's "thermostat" and a way of keeping our brain cool.

A study in Arizona found that people yawned almost twice as much in winter than in summer. That's because their body temperature was higher than the air around them.

When the head begins to heat up, yawning allows cool air to rush in and bring the brain back down to a healthy temperature.

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