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Cool Down to Make Your Thinking Heat Up
Although most of us associate yawning with getting sleepy, researchers now believe it’s a way for the body and mind to fend off sleep and stay alert. They’ve found that brain temperature fluctuates constantly. Yawning is a tool that balances brain temperature and helps maintain the brain’s thermal homeostasis – neither too hot nor too cool. A slight elevation in the temperature of brain tissue can dull your senses. So when drowsiness or boredom clouds thinking, the researchers note, "the mind has to make an effort to maintain contact with the external environment."1A central part of that effort is the yawn. And studies of what happens in the human body during and after a yawn support the idea that a yawn arouses the brain.Physiological Changes Take Place
For instance, as you yawn, your heart rate increases and stays higher after the yawn is finished. Plus, your skin conductance improves – the skin momentarily becomes a better conductor of electricity, which is known to be a sign of arousal. (The caffeine in a cup of coffee also increases skin conductance.)2 Besides that, yawning boosts alpha waves in the brain in a way similar to caffeine. Alpha waves have been linked to increases in creativity and better mood.3 And there’s more: The mechanical action of yawning puts the squeeze on structures in the neck called the carotid bodies. These release a variety of hormones including adenosine and catecholamines which, after a yawn, are believed to regulate the arousal of the brain. This action can also increase blood flow to brain cells.4Wake-Up Call for the Brain
This kind of evidence leads researchers to believe that yawns represent a type of wake-up call to the brain. When you’re bored and getting distracted because something isn’t keeping your attention – lulled by a boring movie, lecture, or a long uninteresting stretch of highway – a yawn helps revive your mental focus.5 One interesting study looked at how various species yawn, and found that animals with larger brains containing more complex neural circuitry experience longer yawns than those with simpler nervous systems.6 You can put some of this yawning information to practical use. For instance, if you find yourself in a situation where you want to keep from yawning – in a boring meeting for example -- you may be able to dodge yawning by breathing through your nose, which keeps your brain cooler than mouth breathing. Cooling your forehead may also help suppress the urge to yawn. If you’re trying to stay awake late, don’t stifle yawns – the cooling action of yawning may help keep you focused and more alert. However, an excessive urge to yawn can be a sign of a serious condition like multiple sclerosis, epilepsy, stress, anxiety or schizophrenia. Central nervous system damage, sleep deprivation, and drugs like Prozac that are serotonin reuptake inhibitors can also cause excessive yawning. But if you’re in good health, you can keep a cooler head and stay more alert with a well-timed yawn.Meet
The Expert:
The Expert:
Carl Lowe has decades of experience writing about health and nutrition for many publications, including Prevention Magazine and Self Magazine (where he served as the food and nutrition editor). He has authored and edited over 10 books about natural health, nutrition, and other subjects. He edited The Columbia University College of Physicians and Surgeons Complete Home Medical Guide and was the nutrition editor for a Time-Life book series on health and nutrition. As a musician, he played viola with the Yale Symphony and bass with the Tommy Dorsey Band, and he has appeared on national TV.
