Few things are more unsettling than being jolted awake by a screaming child. Unfortunately, nightmares are fairly common for preschoolers with growing imaginations.

Psychologists still don't know why we have bad dreams, but they think some are triggered by something stressful that's happened during the day. For your child, that could be anything from a change in his routine to a fight with a friend.

How to react: "If you make a big deal out of a nightmare, you may reinforce its scariness," says Laura Olson, Ph.D., a child-development specialist in Lafayette, IN. Instead:

• Calmly tell your child that he had a bad dream and that it wasn't real. If he seems confused, liken it to a story he made up in his sleep.
• Don't ask him to describe the dream. He'll probably get upset again.
• Don't invite him into your bed unless you want regular visits.
• Leave as soon as he's calm (and still awake): You want him to learn to go back to sleep on his own.
• The next day, help your child think of ways to comfort himself when he has a bad dream: Maybe he'd like a nightlight in his room, or he could try singing a favorite song.

To head off nightmares

• Establish a regular bedtime and evening routine. Consistent sleep cycles and a familiar end to the day may help him feel more relaxed as he's drifting off, which might cut back on nightmares.
• Avoid scary TV shows or movies. Even cartoons can be frightening.
• Don't let older siblings spook him with scary stories.
• If he has frequent nightmares, mention them to your pediatrician and jot down what he does (and even eats) during the day. You might be able to identify the common denominator.
• Kids usually figure out that dreams aren't real by the time they're off to kindergarten, so you can rest assured that you'll both sleep easier soon.