Why Do You Yawn — and Is It Contagious?

The Short Answer from a family medicine doctor

Why Do You Yawn — and Is It Contagious?

Q: Why do you yawn, and is it contagious?

A: Do you ever find yourself yawning when you see someone else yawn?

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We all find ourselves yawning when we feel sleepy or bored, or sometimes, for no apparent reason at all.

There are some interesting myths about this strange thing we do, wide-mouthed and deep with breath. Centuries ago, people believed that you should cover your mouth during a yawn to prevent your soul from leaving the body.

Today, many people have heard the theory that people yawn because the brain needs more oxygen. This simply isn’t true.

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Yawns are useful in opening our eustachian tubes, which regulate air pressure in the middle ear.

Recently, researchers also found that yawning is involved in thermoregulation of the brain, helping the brain maintain its core internal temperature. They found that yawning preceded increases in brain 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.

The study added to other research findings that both spontaneous and contagious yawns arise out of an underlying mechanism involved in regulating your brain’s temperature. So if you yawn after seeing someone else yawn, it’s likely because you’re both in the same area and, thus, exposed to the same temperature environment.

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The same goes for when you feel sleepy or bored. Sleep cycles, boredom and stress are associated with temperature fluctuations in the brain.

Family medicine physician Donald Ford, MD

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