What are the causes, incidence, and risk factors of sleepwalking?
Sleepwalking has been described in medical literature dating before Hippocrates (460 BC-370 BC). In Shakespeare’s tragic play, Macbeth, Lady Macbeth’s famous sleepwalking scene (“out, damned spot”) is ascribed to her guilt and resulting insanity as a consequence of her involvement in the murder of her father-in-law.
Sleepwalking is characterized by a complex behavior (walking) occurring while asleep. Occasionally nonsensical talking may occur. The person’s eyes are commonly open, but have a characteristic glassy “look right through you” character. This activity most commonly occurs during middle childhood and young adolescence. Approximately 15% of children between 4-12 years of age will experience sleepwalking. Generally sleepwalking behaviors wane by late adolescence. However, approximately 10% of all sleepwalkers begin their behavior as teens. It appears that persons with certain inherited genes have an increased tendency toward developing sleepwalking behaviors.
There are five stages of sleep. Stages 1, 2, 3 and 4 are characterized as non-rapid eye movement (NREM) sleep. REM (rapid eye movement) sleep is the sleep cycle associated with dreaming as well as surges of important hormones essential for proper growth and metabolism. Each sleep cycle (stages 1,2,3,4 and REM) last about 90-100 minutes and repeats throughout the night. The average person experiences four to five complete sleep cycles per night. Sleepwalking characteristically occurs during the first or second sleep cycles, during stages 3 and 4. Due the short time frame involved, sleepwalking tends not to occur during naps. Upon waking the sleepwalker has no memory of his or her behaviors.
The sleepwalking activity 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 minutes) or can last for 30 minutes or longer.
One common misconception is that a person sleepwalking should not be awakened. It is not dangerous to awaken a sleepwalker, 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 sleepwalking; however, injuries caused by such events as tripping and loss of balance are common for sleepwalkers.