GETTING AIR
Why do people yawn when they see another person yawn? Is it actually contagious?
This week, we have a question from a reader:
Dear Dr. Prescott: Why do people yawn when they see another person yawn? Is it actually contagious? — Beth Benefield, Moore
Dr. Prescott Prescribes
Yawning is one of the first things our bodies learn to do. Scientists have even determined that fetuses yawn during the first trimester in the womb. Still, no one knows exactly why we do it.
We usually think of yawning as a signal of sleepiness. And it can be. Yet studies have shown that yawning actually correlates not with sleep deprivation but, rather, how sleepy we subjectively feel. That may explain why, in addition to the hour before we hit the sack, we’re most prone to yawning in the hour after we’ve awakened.
Boredom is another state that triggers yawning. (Remember Sasha Obama’s infamous yawn during her dad’s second inaugural address?) Perhaps, some researchers have hypothesized, yawning may serve as a signal for our bodies to snap to.
For many years, the prevailing theory was that we were taking a big gulp of air to deliver a shot of much-needed oxygen to the brain. In the last decade, though, another explanation has increasingly taken hold: Yawning may help cool the brain.
The process of yawning — taking in cool air that changes the temperature of blood flow to the brain — acts like a sort of neural radiator. And chilling the brain seems to make it run better.
This theory may help explain why yawning is, indeed, contagious. If I see you yawning, that might automatically cue an instinctual behavior that says, “If your brain is heating under these conditions, mine may be, too.” (Fun fact: Yawning is even contagious from one species to another, so you can “catch” a yawn from your cat or dog!)
This subconscious copycat behavior could improve alertness — and increase survival chances. Just imagine an ancient ancestor, a hunter-gatherer out on some savanna. Catching a yawn from a fellow tribes person could have made the difference between ending up as the predator or prey.
In other words, from an evolutionary perspective, it makes sense that this trait of yawning contagion would be common in people who survived and reproduced.
Scientists who’ve studied the phenomenon say that yawning is contagious in 60 to 70 percent of the population. And while you might not need this trait to keep you safe from lurking wildlife, it still can prove quite valuable today.
Catching a yawn from a co-worker could stop you from falling asleep in a business meeting. Or maybe a passenger’s yawn has prevented you from nodding off at the wheel of your car.
In other words, the ability to catch a yawn could save your career — or life. As such, it’s no surprise that yawning contagion keeps getting passed down from generation to generation.