Why do people sleepwalk?

Sleepwalking, or somnambulism, usually occurs during deep non-REM sleep in the first third of the night. Brain scans suggest areas controlling movement become active while regions involved in awareness and memory remain in a sleep-like state. It is most common in children, affecting an estimated 5 percent or more at some point, and many outgrow it. Triggers include sleep deprivation, stress, fever, some medications and alcohol, and it tends to run in families. Contrary to myth, gently guiding a sleepwalker back to bed is generally considered safe, though waking them suddenly can cause confusion.