Sweet dreams become nightmares all too often for many young children. In fact, an estimated 25 percent of kids have nightmares more than once a week.

Nightmares aren't real, but they can be frightening for both children and parents alike. Usually, nightmares are nothing to worry about. Most kids simply outgrow nightmares on their own. In the meantime, your calming presence and gentle reassurance can help lull your child back to sleep.

Most nightmares occur late in the sleep cycle, during rapid eye movement (REM) sleep — usually between 4 a.m. and 6 a.m. Your child may wake up frightened and come to you for comfort, recalling the nightmare in vivid detail. Sometimes a single nightmare repeats itself on multiple nights. After a nightmare, your child might resist falling asleep again.

Nightmares are most common in young children, although some teenagers and adults — especially those who have active imaginations — also have occasional nightmares.

Many factors can trigger nightmares, including:

• Stress. Sometimes the ordinary stresses of daily life, such as a problem at home or school, trigger nightmares. A major change, such as a move or the death of a loved one, can have the same effect.
• A traumatic event. Nightmares are common after an accident, injury or other traumatic event.
• Scary books and movies. Reading scary books or watching scary movies, especially before bed, can cause nightmares.
• Bedtime snacks. For some kids, eating right before bed — and the resulting boost in metabolism and brain activity — leads to nightmares.
• Illness. Sometimes being sick triggers nightmares, especially if the illness is accompanied by a fever.
• Medications. Some drugs — including certain antidepressants, narcotics and barbiturates — can trigger nightmares.

Occasional nightmares aren't usually cause for concern. You can simply mention your child's nightmares at a routine well-child exam. Consult your child's doctor earlier if the nightmares:

• Become more frequent
• Routinely disrupt your child's sleep
• Lead to dangerous behavior or injury
• Are accompanied by other signs or symptoms

Nightmares are usually diagnosed at home. The doctor may do a physical or psychological exam to identify any conditions that may be contributing to the nightmares. If your child hurts himself or herself during nightmares, the doctor might want to observe your child in an overnight sleep lab.

Nightmares themselves aren't necessarily a concern, but sometimes a child having a nightmare can hurt himself or herself. If frequent nightmares disrupt your child's sleep, excessive daytime sleepiness might be a problem. Sometimes sleepiness leads to school or behavior problems.

Treatment for nightmares isn't usually necessary.

If the nightmares are associated with an underlying medical or mental health condition, treatment is aimed at the underlying problem. If stress or anxiety seems to be contributing to the nightmares, your child's doctor may suggest meeting with a therapist or counselor.

Medication is rarely used to treat nightmares. If necessary, however, medication may be prescribed to suppress or reduce REM sleep, the sleep stage in which nightmares occur.

If your child is struggling with nightmares, be patient. Sometimes a little creativity helps, too.

• Talk about the dream. Ask your child to describe the nightmare. What happened? Who was in the dream? What made it scary? Then remind your child that nightmares aren't real and can't hurt you.
• Put stress in its place. If your child seems anxious or stressed, talk about what's bothering him or her.
• Rewrite the ending. Help your child imagine a happy ending for the nightmare. Encourage your child to draw a picture of the nightmare, "talk" to the characters in the nightmare or write about the nightmare in a journal.
• Don't go it alone. Your child might feel more secure if he or she sleeps with a favorite stuffed animal, blanket or other comfort object.
• Enlist a guard. If your child is very young, you might assign a doll or stuffed animal the job of "staying awake" all night to guard against nightmares.
• Brighten up. Turn on a night light in your child's room. If your child wakes up during the night, the light might be reassuring.
• Open the doors. Leave your child's door open at night so that he or she won't feel alone. Leave your door open, too, in case your child needs comfort during the night.

Safety counts, too. If your child has frequent nightmares, make sure his or her bedroom is safe. Skip the bunk beds, and consider blocking doorways or stairways with a gate.