The Early Show

Five Little Medical Mysteries

By Ellen Crean

July 14, 2006 / 8:01 AM EDT / CBS

Have you ever wondered why you sometimes get a headache when you eat cold food like ice cream? And do you know what causes hiccups? The Saturday Early Show's Dr. Mallika Marshall unravels five medical mysteries.

Ice cream headache: Many people get an ice cream headache or brain freeze when they eat something cold. There is evidence to suggest that the problem is more common among people who suffer migraines. These people may also suffer headaches if they eat something too hot. When you eat something cold, it hits the roof of your mouth and the nerve endings get over-stimulated. This may temporarily alter blood flow to the brain, giving you a headache.

To prevent it, Marshall suggests eating or drinking more slowly. These headaches typically last for only about a minute; if one goes on longer than that, try drinking a glass of lukewarm water. If you get these types of headaches frequently, you may want to tell your doctor about them.

Is yawning contagious? Marshall says not only is yawning contagious, but it's also instinctual. It's something that you are basically born with the ability to do. Let's say you are in a room with 20 people and one of them yawns. The chances are that within five minutes, half the other people in the room will have yawned and the other half will have thought about yawning.

Yawning isn't the only thing that's contagious, Marshall points out: Laughter is, too.

What causes goose bumps? You get goose bumps when you are cold. When you have a chill, the muscles around your hair follicles contract, which causes the hairs on your body to stand up. This creates an insulation of sorts. All mammals get goose bumps, and it's something humans have been getting since ancient times — when they had much more body hair.

Some people also get goose bumps when they are scared or angry. It's just like when a cat's hair stands on end when they are scared or angry; it makes the animal appear more menacing so that predators will stay away.

What causes hiccups? Hiccups happen when a spasm contracts the diaphragm, which is a large sheet of muscle that separates your chest from your abdomen. The spasm causes you to take in a breath, which is then stopped by the closing of the vocal cords. That's what leads to the hiccup sound.

Hiccups can be caused by many things, including swallowing too much air, eating too fast, smoking and drinking too much alcohol. While they may be annoying, the good news is that hiccups typically last for only a few minutes.

It is not true that you can scare the hiccups out of someone, but there are some steps you can take that may stop them. These steps include holding your breath and counting slowly to 10, quickly drinking a glass of water or eating a teaspoon of sugar or honey.

If hiccups persist even after you've taken steps to try and stop them or you find yourself getting them all the time, you may want to consult your doctor.

What causes joints to crack? Joints crack when the small air bubbles that forms a sac between your joints pop. These sacs act as cushions in the space between your bones. They also help to keep them lubricated.

Asked if persistently cracking your joints causes arthritis, Marshall says, "No. This is one of those cases where your mom isn't right. There is no medical evidence that proves cracking your knuckles will lead to arthritis."

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