During yawning, which is also called oscitation, we take a deep breath of air. Hence, a theory suggested that it helps our body bring in more oxygen and give out carbon dioxide. However, it is incorrect.

A prevailing research suggests that yawning regulates our brain's temperature. Our brain works best at certain temperatures. But when we perform various activities throughout the day, our brain gets exhausted and sleep deprived. Both exhaustion and sleep deprivation increase our brain's temperature. Hence, to cool it down, we yawn.

While yawning, we stretch our jaw and propel blood through blood vessels to the brain. Along with this, we inhale air through our mouth and nose. Air cools the blood going to the brain which in turn decreases our brain's temperature.

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