This is a sleep disorder characterized by walking or other activity while seemingly still asleep. Other names for it are walking during sleep and somnambulism.
The normal sleep cycle involves distinct stages from light drowsiness to deep sleep. in rapid eye movement (REM) sleep, the eyes move rapidly and vivid dreaming is most common. During the night, there will be several cycles of non-REM and REM sleep. Sleepwalking 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.
Sleepwalking may include simply sitting up and appearing awake while actually 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 it can last 30 minutes or longer.
It is not dangerous to awaken a sleepwalker, although it is common for the person to be confused or disoriented for a short time upon awakening. Another misconception is that a person cannot be injured when sleepwalking. Actually, injuries—caused by tripping and loss of balance—are common for sleepwalkers.