The normal sleep cycle involves distinct stages from light drowsiness to deep sleep. During rapid eye movement (REM) sleep, the eyes move rapidly and vivid dreaming is most common. Each night there are several cycles of non-REM and REM sleep. Sleep walking (somnambulism) most often occurs during deep, non-REM sleep (stage 3 or stage 4 sleep) early in the night. It can occur during REM sleep near morning. The cause of sleep walking in children is usually unknown but may be related to fatigue, prior sleep loss, or anxiety. Sleep walking in adults can be associated with mental disorders, reactions to drugs and alcohol, or medical conditions such as partial complex seizures. In the elderly, sleep walking may be a symptom of an organic brain syndrome or REM behavior disorders. The sleep walking activity may include simply sitting up and appearing to be awake while actually being asleep, getting up and walking around, or complex activities such as moving furniture, going to the bathroom, dressing and undressing, and similar activities. Some people even drive a car while actually asleep. The episode can be very brief (a few seconds or minutes) or can last for 30 minutes or longer. One common misconception is that a sleep walker should not be awakened. It is not dangerous to awaken a sleep walker, although it is common for the person to be confused or disoriented for a short time on awakening. Another misconception is that a person cannot be injured when sleep walking. Actually, injuries caused by such things as tripping and loss of balance are common for sleep walkers. Sleep walking can occur at any age, but it happens most often in children aged 6 to 12. It appears to run in families.
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