Somnambulism is a sleep disorder also
commonly known as sleep walk. The above
disorder has been kept in the class of
Parasomnias (1). In the above disorder the
sufferer makes physical activity unknowingly and
believed to be in sleep. Parasomanias can be
defined as undesirable behaviour or experiential
phenomena occurring during sleep or in the
transition to, and from, sleep. Parasomnias can
be divided into three subgroups: disorders of
arousal, disorders of REM sleep, and other
parasomnias. These occur due to abnormal
transitions between the three primary states of
being wake, rapid eye movement (REM) sleep,
and non rapid eye movement (NREM) sleep (2)
.
These conditions occur mainly in sleep. Sleep
can be defined as sleep is a state of decreased
awareness of environmental stimuli that is
distinguished from states such as coma or
hibernation by its relatively rapid reversibility.
Sleeping individuals move little and tend to adopt
stereotypic postures. Although sleep is
characterized by a relative unconsciousness of
the external world and a general lack of memory
of the state, unlike people who have been
comatose, we generally recognize when we feel
sleepy and are aware that we have been asleep
at the termination of an episode. For the clinical
and research purposes sleep can be stated as
sleep is generally defined by combining
behavioral observation with electrophysiological
recording. Humans, like most other mammals,
express two types of sleep: rapid eye movement
(REM) and non-rapid eye movement (NREM)
sleep. These states have distinctive
neurophysiological and psychophysiological
characteristics. REM sleep derives its name from