400 Sleep-Wake Disorders
Diagnostic Features 
The essential feature of non– rapid eye movement (NREM) sleep arousal disorders is the
repeated occurrence of incomple te arousals, usually beginning during the first third of the
major sleep episode (Criterion A), that typica lly are brief, lasting 1–10 minutes, but may be
protracted, lasting up to 1 hour. The maximum duration of an event is unknown. The eyes
are typically open during these events. Many individuals exhibit both subtypes of arousals
on different occasions, which underscores the unitary underlying pathophysiology. The
subtypes reflect varying degrees of simult aneous occurrence of wakefulness and NREM
sleep, resulting in complex behaviors arising from sleep with varying degrees of conscious
awareness, motor activity, and autonomic activation.
The essential feature of sleepwalking is repeated episodes of complex motor behavior
initiated during sleep, including rising from bed and walking about (Criterion A1). Sleep-
walking episodes begin during any stage of NREM sleep, most commonly during slow-
wave sleep and therefore most often occurring during the firs t third of the night. During
episodes, the individual has reduced alertness and responsiveness, a blank stare, and rel-
ative unresponsiveness to communication with others or effo rts by others to awaken the
individual. If awakened during the episode (or on awakening the following morning), the
individual has limited recall for the episode. Af ter the episode, there may initially be a brief
period of confusion or difficult y orienting, followed by full recovery of cognitive function
and appropriate behavior. 
The essential feature of sleep terrors  is the repeated occurrenc e of precipitous awaken-
ings from sleep, usually beginning with a pani cky scream or cry (Criterion A2). Sleep ter-