Why do we grind
our teeth in our sleep?

The full narration of the video.

Grinding your teeth at night doesn't mean you have worms. Creak. Creak. The person next to you is fast asleep, but the grinding keeps you awake. Older folks often say it's roundworms in the belly.

But most people who grind have no worms at all. And doctors advise against taking deworming pills for it on your own. So why do the teeth move by themselves? The switch isn't in the belly. It's in the head. Let's rewind one bout of grinding and see what came right before it.

In a sleep study, wires are taped to the sleeper. Brain, heart, and jaw are all recorded. Rewind a few minutes. The body's stress system quietly starts to rev up. Rewind four seconds. The brain wakes up for a moment. So lightly and briefly, you never notice.

Rewind one second. The heart suddenly speeds up. Only then does the jaw clamp down. Once, twice, a whole string. The order is always the same: brain first, then heart, teeth last.

It's a bit like a car parked at night. The engine idles low, then someone suddenly hits the gas. The rev needle jumps first, and the whole car shudders.

The brain's kick on the gas in sleep is called a micro-arousal. Your heartbeat is the rev needle. Your jaw is the shuddering car. On a sleep study chart, it looks like this: the brain line wiggles first. The heartbeats crowd together. The jaw line sprouts a row of spikes. Except a driver presses a car's pedal. This kick comes from the body itself.

Everyone has micro-arousals, many times a night. Even among people who don't grind, six in ten make gentle chewing movements in their sleep. People who grind just get kicked more often, and harder.

What makes the kicks come more often? Stress, alcohol, smoking, coffee before bed, and snoring with pauses in breathing are all linked to it. Why the jaw, of all things? Scientists are still guessing. Some think a few chews keep the mouth moist and the throat open. Grinding is more common in kids, and many grow out of it.

If your teeth ache in the morning, your jaw hurts, or your teeth are wearing flat, see a dentist. Follow their advice. Dentists often make a night guard. It can't stop the kick on the gas, but it protects the teeth. So that creaking isn't worms. It's your brain hitting the gas in the middle of the night.

In your home, who grinds: a grown-up, or a kid?