Hide this

Story at-a-glance +

  • Yawning is an involuntary behavior that may perform the important function of cooling your brain
  • When you yawn, the influx of cool air may ventilate your sinuses and facilitate brain cooling
  • Brain temperatures increase when you’re sleep deprived, which may be one reason why exhaustion triggers excessive yawning
  • Yawning may also indicate a capacity for empathy, and may be an evolutionarily old process of great social significance

Why Do You Yawn? (It's Not What You Think...)

April 19, 2012 | 199,958 views
| Available in EspañolDisponible en Español
Share This Article Share

By Dr. Mercola

Yawning is usually associated with boredom or being tired, but new research suggests there's far more to this behavior than meets the eye.

The first clue that yawning serves a much greater purpose?

We do it involuntarily, like breathing, and it starts even before we're born (as early as 11 weeks after conception).

There are a number of theories out there for why we yawn, but one of the most compelling is being explored by a Princeton University researcher and his colleagues, whose studies suggest yawning performs the important function of cooling your brain.

Yawning Might Keep Your Brain Cool

A study in Animal Behavior1 explains the hypothesis that "yawning serves as a thermoregulatory mechanism that occurs in response to increases in brain and/or body temperature.

The brain-cooling hypothesis further stipulates that, as ambient temperature increases and approaches (but does not exceed) body temperature, yawning should increase as a consequence."

Indeed, previous research by Andrew C. Gallup, PhD, now a postdoctoral research associate at Princeton University, and colleagues revealed that frequency of yawns more than doubled2 among parakeets when their ambient temperature increased.

New research, this time on humans3, also showed that more people yawned when it was winter compared to when it was summer (45 percent versus 24 percent, respectively), which supports Gallup's theory that people should yawn more in cold weather because the cool air you inhale helps regulate your brain temperature.

He told Discovery News4:

"Brains are like computers... They operate most efficiently when cool, and physical adaptations have evolved to allow maximum cooling of the brain."

To put it simply, it's theorized that the influx of cool air that occurs when you yawn helps cool and increase blood flow in your neck, face, sinuses and head, which together acts like a radiator to cool your brain. Writing in the journal Medical Hypotheses5, Gallup and colleagues suggest this process may also involve your sinuses (the actual function of which is also up for debate):

"The thin posterior wall of the maxillary sinus may flex during yawning, operating like a bellows pump, actively ventilating the sinus system, and thus facilitating brain cooling. Such a powered ventilation system has not previously been described in humans, although an analogous system has been reported in birds."

This finding is in line with previous research that shows brain temperatures increase when you're sleep deprived, which may be one reason why exhaustion triggers excessive yawning. Gallup also suggests that excessive yawning may even be a symptom of health conditions that increase brain and/or core temperature, such as central nervous system damage.

Does Yawning Have Social and Cognitive Implications, Too?

Another theory for why we yawn revolves around its social, rather than its physiological, effects. It's known, for instance, that yawning is contagious among humans, chimps and even dogs, a behavior that is thought to indicate a capacity for empathy6. In the journal Frontiers of Neurology and Neuroscience7, it's suggested that:

"... contagious yawning is a primitive expression of social cognition, namely empathy. Susceptibility to contagious yawning is correlated with the speed in recognizing one's own face, theory of mind processing, and is also associated with activation in regions of the brain that have been associated with social cognitive processes. This suggests that contagious yawning may be an evolutionarily old process that begot a higher level of social cognition in certain species."

Yawning has even been associated with arousal8 or a change of state, such as going from being alert to sleepy or vice versa, according to Dr. Robert Provine9, a neuroscientist at the University of Maryland. For now it's safe to say there's much more to be discovered about exactly why virtually all mammals yawn, but in the event you feel you yawn excessively, be aware that it could have physiologic implications. At the very least, it might mean that you could use a good night's sleep, in which case you can review my 33 sleep aid secrets.

It could also be caused by a vasovagal reaction, which is caused by the action of the vagus nerve (the tenth cranial nerve that runs from your brain stem down to your abdomen) on your blood vessels. This could be a sign of a heart problem and should be checked out by your health care provider. Excessive yawning may also occur before a seizure in people with epilepsy, or prior to the onset of a migraine, so keep this in mind if you suffer from either.

What Are GMOs?

From April 19th through April 25th we launch GMO Awareness Week. We set aside an entire week dedicated to providing you with information on GMOs and labeling initiatives.

GMOs are a product of genetic engineering, meaning their genetic makeup has been altered to induce a variety of “unique” traits to crops, such as making them drought-resistant or giving them “more nutrients.” GMO proponents claim that genetic engineering is “safe and beneficial,” and that it advances the agricultural industry. They also say that GMOs help ensure the global food supply and sustainability. But is there any truth to these claims? I believe not. For years, I've stated the belief that GMOs pose one of the greatest threats to life on the planet. Genetic engineering is NOT the safe and beneficial technology that it is touted to be.

Help Support GMO Labeling

The Grocery Manufacturers Association (GMA)—Monsanto’s Evil Twin—is pulling out all the stops to keep you in the dark about what’s in your food. For nearly two decades, Monsanto and corporate agribusiness have exercised near-dictatorial control over American agriculture. For example, Monsanto has made many claims that glyphosate in Roundup is harmless to animals and humans. However, recently the World Health Organization (WHO) had their research team test glyphosate and have labeled it a probable carcinogen.

Public opinion around the biotech industry's contamination of our food supply and destruction of our environment has reached the tipping point. We're fighting back. That's why I was the first to push for GMO labeling. I donated a significant sum to the first ballot initiative in California in 2012, which inspired others to donate to the campaign as well. We technically "lost the vote, but we are winning the war, as these labeling initiatives have raised a considerable amount of public awareness.

The insanity has gone far enough, which is why I encourage you to boycott every single product owned by members of the GMA, including natural and organic brands. More than 80 percent of our support comes from individual consumers like you, who understand that real change comes from the grassroots.

Thankfully, we have organizations like the Organic Consumers Association (OCA) to fight back against these junk food manufacturers, pesticide producers, and corporate giants.

Internet Resources Where You Can Learn More

Together, Let's Help OCA Get The Funding They Deserve

Let’s Help OCA get the funding it deserves. I have found very few organizations who are as effective and efficient as OCA. It’s a public interest organization dedicated to promoting health justice and sustainability. A central focus of the OCA is building a healthy, equitable, and sustainable system of food production and consumption. That's why I'm proud to announce I will be matching donations up to $250,000 this week.

Please make a donation to help OCA fight for GMO labeling.

Donate Today!

Thank you! Your purchases help us support these charities and organizations.

Food Democracy Now
Mercury Free Dentistry
Fluoride Action Network
National Vaccine Information Center
Institute for Responsible Technology
Organic Consumers Association
Center for Nutrtion Advocacy
Cornucopia Institute
Vitamin D Council
GrassrootsHealth - Vitamin D*action
Alliance for Natural Health USA
American Holistic Veterinary Medical Foundation
The Rabies Challenge Fund
Cropped Catis Mexico