Most sleepwalkers have no memory of the event

Q: I am an 82-year-old woman. When I was in my teens, I did some sleepwalking. A recent occurrence during the night is making me wonder if I have sleepwalked again. What are some of the things that sleepwalkers have been known to do?

A: From the time of the ancient Greeks, people have been writing about the mysterious behavior we call sleepwalking. Hippocrates and Aristotle alluded to it in their writings, Shakespeare used it to reveal a character in "Macbeth," and a sleepwalker sets in motion the plot of the novel "Dracula."

Formally referred to as somnambulism, sleepwalking is one of a larger group of sleep disorders known as parasomnias. During an episode of sleepwalking, the sleeping individual engages in behaviors as if they were awake. These can range from speaking, to getting out of bed and walking around, to completing complex tasks such as dressing, eating, bathing, cooking, rearranging furniture and cleaning the house. In some cases, sleepwalkers engage in violent behavior that puts them - and their sleep partners - at risk of injury.

One thing the majority of sleepwalkers have in common is a lack of awareness of the experience as it takes place, and no memory of it upon awakening. Many sleepwalkers have discovered their sleepwalking through the discovery of physical evidence of an episode, such as waking up fully dressed or finding the kitchen filled with dirty dishes.

The disorder is estimated to affect from 2% to 15% of the population. It's more common in children than in adults, and it is believed to have a genetic component. Episodes of sleepwalking, which can last from a few moments to more than an hour, most often occur during the nonrapid eye movement (NREM) stages of sleep. These are the deeper, dreamless stages of the sleep cycle. Studies show that about half of those who sleepwalk do it once a week.

Although the disorder has been linked to stress, anxiety, alcohol use and poor-quality sleep, the exact cause is not yet fully understood.

Symptoms of sleepwalking include a glazed or glassy-eyed appearance, not communicating with others despite appearing to be awake, being difficult to awaken while an episode is taking place and feeling confused or disoriented when an episode is interrupted. People who sleepwalk rarely remember anything that took place during an episode. However, the disorder takes a toll on them physically.

Occasional episodes of sleepwalking aren't considered to be cause for concern. However, if you suspect you're experiencing repeated incidents, we think it's wise to check in with your family doctor. Sleepwalking accounts for the majority of sleep-related injuries, and it can cause drowsiness and exhaustion due to interrupted sleep. The condition can also be a sign of an undiagnosed sleep disorder or other medical condition.

There is no known cure for sleepwalking. Your doctor can help you to identify potential triggers and suggest ways to create a safer environment to prevent injury.

• Dr. Eve Glazier, is an internist and associate professor of medicine at UCLA Health. Dr. Elizabeth Ko is an internist and assistant professor of medicine at UCLA Health. Send your questions to askthedoctors@mednet.ucla.edu.