Nightmare disorder is referred to by doctors as a parasomnia — a type of sleep disorder that involves undesirable experiences that occur while you're falling asleep, during sleep or when you're waking up. Nightmares usually occur during the stage of sleep known as rapid eye movement (REM).

You normally go through four to six sleep cycles a night, cycling through the sleep stages in about 90 minutes. Your REM stage lengthens with each cycle, from several minutes in the first cycle to up to an hour in the last. You're more likely to have a nightmare in the second half to the last third of your night.

A nightmare may involve these features:

• Your dream seems vivid and real, often becoming more disturbing as the dream unfolds
• Your dream storyline is usually related to threats to your safety or survival
• Your dream wakes you
• You feel scared, anxious, angry, sad or disgusted as a result of your dream
• You feel sweaty or have a pounding heartbeat, but do not leave the bed
• You can think clearly upon awakening and can recall details of your dream
• Your dream occurs near the end of your sleep time
• Your dream keeps you from falling back to sleep easily

You may have nightmare disorder if, in addition to the above:

• The sleep disturbance causes significant distress or problems with functioning during the day
• Medications or physical or mental disorders do not adequately explain the fact that you have nightmares

Children's nightmare content varies with age, typically becoming more complex. While a young child might dream of monsters, an older child might have nightmares about school or difficulties at home.

When to see a doctor

Occasional nightmares aren't usually a cause for concern. If your child has nightmares, you can simply mention them at a routine well-child exam.

Talk to your doctor sooner if nightmares:

• Occur frequently and persist over time
• Routinely disrupt sleep
• Cause fear of going to sleep
• Cause daytime behavior problems

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Aug. 09, 2014