By Karen Higman

If your child pierces the night with a blood-curdling scream when she's sleeping like my 6-year-old daughter did recently – but doesn't wake up during the episode – she's having a night terror, a common childhood phenomenon. Not to worry. Although night terrors can be a sign of something more serious, they're typically harmless. Here's what you need to know about what triggers night terrors, how they differ from nightmares, and what you can do to prevent and cope with them.

What are night terrors? Medically known as a parasomnia, a night terror (a.k.a. sleep terror) is a sleep disorder that occurs during the first half of the night, in the initial slow-wave phase of sleep, when your child is sleeping the deepest. "With a classic case, a child will scream out or cry," says Judith Owens, M.D., associate professor of pediatrics at the Warren Alpert Medical School of Brown University and a member of the National Sleep Foundation's Pediatric Sleep Task Force. A night terror can be scarier for you than your child because she won't even know she's having one. During a night terror, a child doesn't wake up, won't respond to soothing or comforting, or remember the episode the next day. Although screaming is a classic sign, a night terror can also take subtler forms. A child may just mumble or appear slightly agitated. Her eyes might even be open. An episode can last as long as five minutes before a child returns to normal sleep.

Are night terrors the same as nightmares? No. Nightmares, medically known as partial arousal parasomnias, happen during the second half of the night during rapid eye movement (REM) sleep, toward the morning hours, when most dreaming occurs. Because your child is sleeping less deeply during a nightmare, she may wake up, respond to soothing and even remember it afterwards. And after a nightmare, it can take a while for kids to get back to sleep.

How common are night terrors? They affect up to 3 percent of all kids, especially from age 4 to 8, and less than one percent of adults. They're more common in children because kids spend 25 to 50 percent of the night in deep sleep. The duration of the night we spend in deep sleep shortens with age. Adults over age 20 devote just 15 percent of the night to deep sleep. As children's brains mature and the architecture of their sleep changes, they become less susceptible to night terrors. "Ninety percent of kids outgrow night terrors by adolescence," Dr. Owens says.

Are night terrors dangerous? They're not. "Even though a child looks frightened and alarmed during a night terror, there's no deep-rooted psychological issue that's causing them or long-term repercussions in terms of psychological development or emotional distress," says Dr. Owens. Night terrors don't contribute to nocturnal problems like bedwetting, or decreased performance in school, she says. But children who have night terrors are also prone to sleep walking. Sleep walking is a related parasomnia that also occurs during deep sleep; 10 percent of kids who sleep walk also have night terrors. "Because sleepwalking involves getting out of bed, kids can injure themselves. They can fall down stairs or let themselves out of the house," says Dr. Owens. If your child is a sleepwalker, protect her from hurting herself by leaving the light on in the bedroom or hallway and keep obstacles out of her way and lock doors and low windows.

Take back the night: Preventive Pointers for Night Terrors
"Most children have a genetic predisposition to night terrors, so it's usually a matter of looking for triggers and avoiding them," says Jodi Mindell, professor of psychology at Saint Joseph 's University in Philadelphia and co-author of Take Charge of Your Child's Sleep (Marlowe, 2005). Anything that disrupts or lengthens slow-wave sleep can trigger night terrors. Here's what you can do to prevent them:

Keep bedtime consistent. Skimping on sleep is the most common cause of night terrors. "When kids are sleep deprived, they tend to sleep more deeply to compensate," says Dr. Owens, which makes them more susceptible to night terrors. Keep sleep and wake times as consistent as possible, even when you're traveling or visiting relatives and during special occasions. "Avoid late nights and missed naps," says Dr. Mindell. If night terrors persist, try putting your child to bed earlier.

Curb caffeine. Caffeine can trigger night terrors because it can disrupt slow-wave sleep, so remove caffeinated soft drinks, coffee drinks and other products from your child's diet.
Expect night terrors when kids get sick. "Kids are more likely to have a sleep terror when sick or when experiencing pain, such as from an ear infection," says Dr. Mindell. Certain medications that lengthen slow-wave sleep, such as chloral hydrate, which is sometimes given to kids to help them sleep, can trigger night terrors. Other medications, such as lithium, can cause night terrors, but it's rarely given to young children, says Dr. Mindell. Nonetheless, if your child is on medication and has frequent night terrors, "stop using the medication and contact your doctor," she advises.

Warn others. "Night terrors are more likely to happen when sleeping away from home," says Dr. Mindell. So if your child is prone to night terrors and spending the night at grandma's or a friend's house, or at camp, warn everyone that it might happen and not to be alarmed. A change of environment can also prompt one, says Dr. Owens. When my daughter had a recent night terror, for example, she was in a sleeping bag on the floor of our bedroom because an overnight guest was sleeping in her bed.

Night Terror Dos and Don'ts
When a night terror strikes, here's what to do and not do:

Do nothing. "It's best not to try to soothe your child because it usually makes the episode worse and makes it last longer," says Dr. Mindell. "It's better to simply be nearby, without even saying your child's name, to be sure she doesn't hurt herself."

Don't discuss it the next day. Talking about it may make your child anxious about going to sleep, which can lead to sleep deprivation and increase the likelihood of another night terror, Dr. Mindell says.

Do turn off the TV at least 30 minutes before bedtime, and keep a TV out of your child's bedroom. Frightening images or movies before bed don't trigger night terrors, says Dr. Owens. Still, they might cause nightmares, so limiting TV before bed is a just a good general habit to get into.

Sandra Gordon is a freelance writer and frequent contributor to GVP.