Q. My son is almost 3 and he is waking up at night crying and saying "the monster is under my bed." Is he too young to be having nightmares?

A. Children your son's age can certainly have nightmares -- and there are things you can do to help him.

First, think about possible causes. Did he watch TV right before going to bed? Even a cartoon that's usually fine might have affected his sleep. Did he see the evening news as you were watching? News programming often contains images that can scare a young child. Did he see part of a frightening movie you were watching? Be careful about what he sees.

What did he eat before going to bed? Experts say that some additives and foods -- such as cheese and chocolate -- can stimulate children's brains in ways that can produce nightmares.

Then think about prevention. Make sure you have a calming routine leading up to your son's bedtime: a relaxing bath, a soothing story (there are many wonderful books for kids his age), a soft song once the lights are out, then lots of kisses. The more relaxed a child is before going to sleep, the less the likelihood of nightmares.

If he does have a nightmare, listen to what he says about it and react to that. Be calm and reassuring, and don't belittle his fears, which are very real for him. If he believes there's something under his bed, check with him so he sees there's nothing there. Check the closet and windows, too. The goal is to calm and reassure him so he can get back to sleep.

One thing you do not want to do is take him into your room after a nightmare. This sends the message that his room isn't safe and comfortable -- and you'll be starting a routine that will be very hard to break.