A yawn is a yawn is a yawn.
When it calls, we must surrender. Mouth agape, head thrown back, eyes squeezed, brows rippled, all that expensive dental work revealed, we strike a most unfetching pose, sometimes even unleashing a primal groan. Killer yawns (up there with satisfying sneezes in my book) bring tears to your eyes.
But why do we yawn? Is it more than a reflex to pump extra oxygen into our weary brain when it's bored or tired? And why do we automatically yawn just because we see someone else do it?
Yawning is "extremely contagious," says Robert Provine, a psychology professor at the University of Maryland who has studied the yawn for 10 years, focusing on that famously lethargic creature, the college undergrad.
"Seeing someone yawn, thinking about it and even reading about it makes you yawn, something that does not happen with the hiccups," he says.
A brain mechanism attuned to detect a yawning face may trigger the behavior in others, Provine says. Once that neurological machinery is activated, it must go to completion. No one has ever reported the ability to inhibit a yawn, he says.
Yawning--which stretches the head and neck and often the back, shoulders and arms--occurs during transitions: sleep to waking, alertness to boredom, and relaxation to nervousness, Provine says.
Whatever causes yawning, it isn't mere oxygen deficiency, says Provine, who claims to have disproved that folklore in a study where people who breathed gas mixtures rich in carbon dioxide yawned no more than those who breathed ordinary air or pure oxygen.
Scientists infer from various research that yawning is linked to dopamine, a brain chemical that transmits commands from the muscle control center. Dr. Samarthji Lal, a psychiatry professor at McGill University in Montreal, found that apomorphine, a drug that stimulates the brain's dopamine receptors, induced yawning (and penile erections) in patients. Some antidepressants, Lal says, produce yawning and orgasm simultaneously. (Sign me up!)
The physiological effects of yawning are largely mysterious, but Temple University psychology professor Ronald Baenninger, who studied yawning for 20 years, says he believes it jolts the brain.
"Studies done in Italy and Japan suggest that [yawning] seems to shunt blood up to the brain, increasing arousal and brain use"--and making us feel good.
Testosterone and aggression also may be linked to yawning, says Baenninger, with higher testosterone males yawning most. Non-human primate males yawn about twice as much as females, he says. Highly aggressive Siamese fighting fish yawn "like crazy" right before they engage in battle, but do little yawning when alone. Castrated males yawn less.
But the critical question, says Dr. Mary Carskadon, a psychiatry professor at Brown University and director of the Bradley Sleep Research Lab, is whether yawning has a reverse effect, making one sleepy instead of sleepiness making one yawn. (In one study where a man simply thought about yawning, he yawned a whopping 76 times in 30 minutes. Talk about brain power.)
"Maybe one can hyper-yawn oneself [into unconsciousness]," Carskadon says, her dozen or so yawns during our interview immediately inspiring hyper-yawning in me. Anyway, that's the last thing I remember . . . before I passed out into a coma / nap.