Question: What is thought to cause hiccups and yawns?

Great questions!

Everybody yawns — from unborn babies to the oldest great-grandparent. Animals do it, too. But why, exactly, do people and animals yawn? No one knows for sure. But there are many theories (ideas) about why people yawn.

One is that when we are bored or tired, we just don’t breathe as deeply as we usually do. As this theory goes, our bodies take in less oxygen because our breathing has slowed. Therefore, yawning helps us bring more oxygen into the blood and move more carbon dioxide out of the blood.

Yawning, then, would be an involuntary reflex (something we can’t really control) to help us control our oxygen and carbon dioxide levels. Sounds good, but other studies have shown that breathing more oxygen does not decrease yawning. Likewise, breathing more carbon dioxide does not increase yawning. Hmmm. Now what?

Another theory is that yawning stretches the lungs and lung tissue. Stretching and yawning may be a way to flex muscles and joints, increase heart rate, and feel more awake.

And hiccups… The part to blame is your diaphragm. This is a dome-shaped muscle at the bottom of your chest, and all hiccups start here.

The diaphragm almost always works perfectly. When you inhale, it pulls down to help pull air into the lungs. When you exhale, the diaphragm relaxes and air flows out of the lungs back out through the nose and mouth.

But sometimes the diaphragm becomes irritated. When this happens, it pulls down in a jerky way, which makes you suck air into your throat suddenly. When the air rushing in hits your voice box, you’re left with a big hiccup.

Some things that irritate the diaphragm are eating too quickly or too much, an irritation in the stomach or the throat, or feeling nervous or excited. Almost all cases of the hiccups last only a few minutes. Some cases of the hiccups can last for days or weeks, but this is very unusual and it’s usually a sign of another medical problem.