The Yawn Explained: It Cools Your Brain

It's now believed yawning operates like a radiator for birds and mammals.

If air in the atmosphere is cooler than brain and body temperatures, taking it in quickly cools facial blood that, in turn, cools the brain and may even alter blood flow. Prior studies reveal yawning leads to a heightened state of arousal, so a morning yawn may function somewhat like a cup of coffee in providing a jolt of energy.

The new findings also explain why tired individuals often yawn, since both exhaustion and sleep deprivation have been shown to increase deep brain temperatures, again prompting a yawn-driven cool down. Yawning additionally appears to facilitate transitional states of the brain, such as going from sleep to waking periods.

Gordon Gallup, Jr., a State University of New York at Albany psychologist, did not work on the study, but, as Andrew Gallup's father, paid close attention to the research. The senior Gallup also happens to be a leading expert on the science of yawning and other widespread evolved traits.

"It is interesting to note that instances of excessive yawning in humans may be indicative of brain cooling problems," Gallup, Jr., told Discovery News, pointing out that patients with multiple sclerosis often experience bouts of excessive yawning "and MS involves thermoregulatory dysfunction."

"Bouts of excessive yawning often precede the onset of seizures in epileptic patients, and predict the onset of headaches in people who suffer from migraines," he added.

In the future, researchers may focus more on brain temperature and its role in diseases and their symptoms. But the new study on yawning changes the popular notion that yawns are mere signs of boredom.

On the contrary, as Gallup said, "yawning more accurately reflects a mechanism that maintains attention, and therefore should be looked at as a compliment!"

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