The Scientific Explanation Behind Yawning
Yawning is something humans and other mammals do every day, averaging anywhere from 5-10 yawns every day, according to the Sleep Foundation. Yawning is a reflex that involves opening the mouth and taking a deep inhale to fill the lungs with air and yawns generally last 5-10 seconds. For something that we do so often, we still don't know everything about yawning.
That being said, there are some explanations as to why we do it. You may have heard that yawning is triggered by a lack of oxygen to the body. While the hypothalamus in the brain does sense low oxygen levels, this is probably not the sole reason why we yawn, according to Scientific American.
A yawn seems to be contagious, but again, no one can explain why. Some theories suggest that at one point in our evolutionary history, yawning was a way to communicate (per the Sleep Foundation). Because of this reflex, New Scientist points out that yawns can be spontaneous and contagious, making the science behind them even more unclear.
Yawning appears to help regulate bodily functions
We do know that many people yawn when they are sleepy. While you may be tired when you yawn, the reflex might be more of a reaction to changes that are occurring within your body. For example, you yawn before bed as well as after you wake up, both of which are situations where your attention levels are changing (via Scientific American).
Sometimes, a yawn helps regulate the temperature of your brain by cooling it off. A 2014 study published in Physiology & Behavior showed that people yawned less in cooler temperatures. Yawning also helps regulate ear pressure, which is most noticeable during situations where the altitude changes (via Sleep Foundation).
Excessive yawning can indicate a lack of sleep, but continuous episodes may be linked to an underlying condition, such as a neurological disorder or brain condition. According to Medical News Today, yawning too much can even indicate heart problems. If you think you are yawning too often, it's a good idea to discuss it with your doctor.