Sleepwalking is a sleep disorder effecting an estimated 10 percent of all humans at least once in their lives (1). This widespread phenomenon varies in its intensity and frequency. While most sleepwalking incidents are short and not dangerous, some can involve self-injury and are much more dangerous for the sleeper. Also, most interestingly, the disorder seems to stem from many different sources, not from one definable cause such as a chemical imbalance. While it is predominantly pre-adolescents who suffer from somnambulism, it is also observed in adults, although the frequency and severity of incidents increase with age. The source of the disorder was once thought to be entirely psychological and an extension of dreaming. It is now understood to be a complex combination of one or more factors, such as psychological and physiological factors as well as chemical interference (such as alcohol and drug abuse) (3). The source of the sleepwalking behavior varies according to age with the younger sufferers having more physiological problems which they grow out of, while older somnambulists, stress and substance abuse play a larger role.
Somnambulism is most common among children from the ages of 4 to 12 (3). Estimates for the percentage of the population which will sleepwalk at least once in their lifetime range quite a bit. Some sources say that most children will walk in their sleep at least once, with 15% sleepwalking more regularly (3). Others claim that 18% of the population is "prone to sleepwalking" (9). There is consensus, however, on the fact that boys sleepwalk more frequently than girls and that it is between the ages of 11 and 12 that the most cases of sleepwalking are reported (9). The fact that most children grow out of it after puberty and that people who start sleepwalking later in life tend to have the problem for the rest of their lives (9) seems to suggest that there are at least two classes of somnambulism, which may stem from different sources.
Sleepwalking most often occurs at a certain point in the sleep "architecture" (6).This is the point where the sleeper's brain waves have become larger and he or she has moved into deeper sleep. This is not REM sleep, but deep non-REM sleep. The series of complex behaviors characterizing somnambulism includes "amnesia following an episode," and "difficulty in arousing the patient during an episode" (9). The patient can also have other REM disorders or psychiatric and medical disorders which do not account for the sleepwalking. While sleepwalking, the patients' brainwaves show a mixture of types of brainwave patterns, including ones similar to those observed in waking patients, as well as those found in deep sleep. It is the "awake" patterns which match the waking behaviors like walking and talking while the patient is still asleep enough so that he or she is not aware of what it happening and is not forming memories of their actions
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