Why Do People Yawn?


One of the most recognizable and universal human actions is the yawn. If you’ve been staring too long at your computer screen or if you just didn’t get enough sleep last night, you may be inclined to open your mouth wide, stretch out your arms, and yawn.

It happens so much that we generally don’t even think about it and in many cases may not even notice it. It’s long just been associated with sleepiness, but of late, there’s been more interest in trying to find out if there’s more to yawning. Because it went mostly unstudied for years, we still don’t have definitive conclusions, but we do know more about what yawning is and how it may affect the body.

In this article, we’ll explore what a yawn really is, why we yawn, and whether there is such a thing as too much yawning. So take a deep breath, stretch out, and read on to learn more.

What is a Yawn, Really?

While we all know a yawn when we see one, we may not typically consider what actually constitutes a yawn. In general, a yawn has 3 parts: a long inhalation, an opening of the mouth, and a pronounced exhalation (that is often very audible). An extended stretching of limbs may occur at the same time. In some cases, a person may try to close their mouth to disguise their yawning, but they aren’t fooling anyone.

The takeaway is that this pronounced inhalation and exhalation process, which usually lasts up to a few seconds, is what separates yawning from other breathing.

Why do People Yawn?

Yawning is not a new phenomenon. It’s a long-standing bodily function and one that has traditionally been thought of as caused by tiredness or boredom. While there does seem to be an association with those triggers, research has found that not all yawning can be explaining by sleepiness or boredom. As a result, there have been a number of attempts to understand the underlying biological explanations for yawning. To date, no one theory has universal acceptance, but there is some evidence support several of them. Each of the following is a possible explanation for yawning:

  • Yawning as a sleep trigger: because yawning has for so long been related to sleepiness, one possible explanation is that yawning can spur a transition to activate the body’s sleep systems. However, people yawn even when they are not tired, and many yawn without falling asleep. For these reasons, though yawning may have a relationship with generating sleep in some cases, this doesn’t appear to be a strong explanation for yawning in general.
  • Yawning as a way to refocus and gain attention: when something doesn’t stimulate the brain, a person may yawn. Some research indicates that the act of yawning may produce a stimulating effect that helps us try to keep our focus despite the lack of stimuli. This stimulus has been detected both in the brain and on the skin, which gives further credence to this potential role of yawning.
  • Yawning as a way of regulating temperature: this theory initially came from research in rats that found that yawning may serve as a way of reducing brain temperature. In both animals and people, signs point to yawning becoming more frequent when someone is starting to overheat. Yawning increases blood flow around the brain and facial muscles, which has a cooling effect along with the acts of inhalation and exhalation. The body has numerous processes designed to help with thermoregulation (temperature management), so it would not be surprising for a common act like yawning to be a part of this system of the body.
  • Yawning to release pressure in the ear canal: you may have noticed that yawning can help “pop” your ears when you’re dealing with changes in altitude. As a result, one theory about yawning is that serves as a way to help protect the ear by managing pressure in the Eustachian tube. But since there are so many cases of yawning that are not associated with ear pressure, it appears that this is probably a secondary rather than primary biological role of yawning.
  • Yawning to release “bad air”: this theory holds that yawning served to expel CO2 and increase oxygen levels in the brain. However, more recent research introduced volunteers to air that had higher CO2 concentrations, but this did not stimulate increased levels of yawning. As a result, this theory has been discounted and likely does not explain the biological purpose of yawning.

Ultimately, this field of research still has a ways to go before we will know for sure why we yawn. Currently, there is a lack of conclusive evidence because of limits to the studies that have been done so far. It may be that yawning serves multiple biological roles, but further research is necessary to really understand the complexity of this seemingly simple act.

Is Yawning Contagious?

If you’ve ever been in a boring meeting or class, you’ve probably seen how one person’s yawn can ripple across the room. Based on this observed effect in more casual situations, some researchers decided to see if it could be replicated in scientific settings with both people and animals (in particular, chimpanzees). The results of these studies suggest that there is definitely a contagious effect from yawning.

Researchers sometimes refer to this as the empathic role of yawning, and it may be connected to mirror neurons, which are part of the brain’s way of relating to others. Brain studies have found activation in response to yawning in parts of the brain that would be associated with this type of empathic and communicative role of yawning. For this reason, we can safely say that the research to date points to yawning being contagious.

Does Yawning Always Mean You’re Tired?

No. There are too many other roles for yawning for it to only be associated with tiredness.

If you’ve ever spent an early morning in an airport, you know that clearly being tired can be a cause for someone to yawn. However, clearly, drowsiness is not sufficient as the only explanation of yawning. Yawning can happen as a result of a lack of stimuli, in response to someone else yawning, or as mentioned previously, as a way to help cool down or to alter ear pressure. So despite our common association of yawning with drowsiness, a yawn does not always mean that a person is sleepy.

Can You Yawn Too Much?

Yes. There is such a thing as excessive yawning, and it can be a condition that needs to be addressed with a health professional. Though determining what is “excessive” can be a challenge, in general, if it seems like you have uncontrolled yawning or just notice that you’re yawning a lot more than normal or than other people, it may be an issue. Often this is associated with excessive daytime sleepiness, which can be related to sleeping problems like insomnia. General fatigue or drowsiness may also be a cause for excessive yawning. Other potential explanations are more rare but include stimulation of the vagus nerve by a heart attack or stroke, brain disorders (such as epilepsy, a tumor, or multiple sclerosis), some medication, or conditions that limit the body’s ability to regulate temperature.

Remember, to yawn is normal, so when problems arise, it’s usually noticeable that the yawning is more than what’s to be expected. It’s also important to emphasize that most of the time, excessive yawning isn’t caused by these more serious issues. However, it is still a good idea to see a doctor or nurse if you notice that your patterns of yawning have changed. If you’re feeling regular daytime sleepiness and find yourself yawning more and more or yawning uncontrollably, check in with your doctor who can get more information and order any tests that may be necessary.


For such a simple and everyday act, yawning has a fascinating physiological background that is still in many ways shrouded in mystery. Though we know much more know that we did even only a decade or two ago, we still can’t say exactly why we yawn. But with more studies and research, it can be expected that we’ll learn more and more about the various roles of yawning and why we yawn when we do. Until that time, we hope you found this article stimulating enough that you didn’t let out any yawns!

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