We all do it, and we all know it has at least something to do with how tired we feel. But unlike sleep apnea or laptops in the bedroom, yawning is an aspect of sleep that researchers haven’t quite figured out just yet. Here are 6 facts when it comes to yawning.
There Are Many Theories, But Little Proof
There’s little research to support any of a number of theories as to why we yawn. First off, we don’t only do it when we’re tired. It also probably doesn’t reflect a lack of oxygen, although that theory isn’t a totally nutty one. The idea likely blossomed from the fact that too-shallow breathing can cause problems, says Michael Decker, Ph.D., associate professor at the Frances Payne Bolton School of Nursing at Case Western Reserve University and a spokesperson for the American Academy of Sleep Medicine.
The bottom lobes of the lungs aren’t usually called upon when we’re in our resting state. It isn’t until we exercise that we typically use more of our lung capacity, but such deep breathing helps keep the lungs healthy, he says. In cases of surgery patients, some have been known to lose lung function after developing pneumonia due to shallow breathing after anesthesia. “Yawning would be like a homeostatic response to not breathing deeply” if this theory were to hold up, says Decker, but there’s little proof to suggest it’s the primary reason for yawning.
Yawning does seem to increase with boredom, at least according to a small 1986 study of college students who yawned more when shown a pattern of colors than when shown a 30-minute rock video.
The most recent research on yawning suggests that it exists to cool down the brain. That open-mouthed yawn causes sinus walls “to expand and contract like a bellows, pumping air onto the brain, which lowers its temperature,” National Geographic reported. The study found that people were more likely to yawn during the winter, when the exterior air is obviously cooler, than in the summer, when yawns won’t do much in terms of bringing cold air inside, Healthy Living reported.