It’s your brain’s way of waking you up
It’s no coincidence that you frequently yawn when you feel your eyelids droop and you start daydreaming about your warm bed. In fact, a yawn might be your brain attempting to jolt you awake when you’re sleepy.
Researchers have theorized that as yawning forces your face and neck to move, this causes stimulation of your carotid artery. In turn, this causes your heart rate to increase and even to move your brain into more of an “active state.”
It helps relieve pressure
Have your parents ever told you to try and yawn on purpose to help pop your ears when a plane lands? Well, turns out there may be some science to that tip.
In fact, that’s why your body often will set off a yawn as a way to relieve pressure. But the same effect also happens when we swallow — so researchers can’t say for sure if this is the main reason that we yawn.
It helps regulate brain temperature.
Researchers have also found that yawning helps thermoregulate your brain — meaning helping your brain maintain its core internal temperature.
“They theorized that just as your computer has its own cooling mechanism to keep it from overheating, your body’s computer — the brain — uses yawning to regulate its temperature,” says Dr. Ford.
It does this in a couple of ways. Various studies have found that when we yawn, we inhale a large amount of air into our lungs, which then cools the blood vessels in our head and neck. Additionally, the facial muscles in our jaw and cheeks stretch, adjust and contract, which could help ventilate our sinuses and further cool our brain. You may have also noticed that when you yawn, it can cause you to tear up, which also releases heat.
This theory may play hand in hand with the theory that yawning is a way to make your body more awake or alert. “Sleep cycles, boredom and stress are associated with temperature fluctuations in the brain,” adds Dr. Ford.
Is it possible to yawn excessively?
OK, now the person next to you in the meeting is giving you a side-eye because you’re on your third yawn in a row. But it’s not your fault if that’s how your body is reacting!
In addition to wondering why you yawn, you may also wonder if it’s a problem if you yawn excessively. What’s the yawning limit? It may surprise you to know that the average person yawns about 20 times a day — so, you’d have to yawn a lot more than that before you should be concerned.