Picture this- you’re being grilled at an extremely important interview. You’re a bag of nerves but you’re holding it together and actually doing pretty well when suddenly you feel that dreaded feeling inside you. It’s something you cannot suppress but you try and exercise damage control by ensuring you keep your mouth closed. As a result, your nostrils flare, your lips appear distorted, and your watery eyes are a dead giveaway. Your yawn gets the better of you.
Yawning has puzzled scientists for the last 2500 years, starting with Hippocrates who believed that yawning helped release noxious air, especially during a fever. Since then, several theories have been proposed ranging from physiological ones like yawning boosting oxygen levels in the blood to evolutionary theories that suggest yawning was an early form of communication. Contrary to popular belief, yawning isn’t a sign of boredom but could be a mechanism of coping with stress. Studies have cited paratroopers yawning before jumping off their planes and Olympic athletes yawning prior to a race. Similarly, vertebrate predators from mammals to fish have been recorded yawning before a hunt.
While there is no universally accepted theory on why adult humans yawn yet, recent research at the University of Albany shows that humans yawn in order to lower the temperature of their brains and remain more alert in the event of possible danger. The violent jaw movements ensure blood flow around the skull which carries away excess heat, while the deep inhalation brings cool air into the sinus cavities and around the carotid artery leading back into the brain. What’s more, the strenuous movements could also flex the membranes of sinuses – fanning a soft breeze through the cavities that should cause our mucus to evaporate, which should chill the head like air conditioning.
Similar to a fan in a computer, it is speculated that yawning draws in cooler air and optimizes neurological function at a time when people are drowsy and therefore more vulnerable. Cooler brains can think more clearly, hence, yawning might have developed to keep us alert.