Non–Rapid Eye Movement Sleep Arousal Disorders 399
Parasomnias 
Parasomnias are disorders characterized by abnormal behavioral, experiential, or physio-
logical events occurring in association with sleep, specific sleep stages, or sleep-wake tran-
sitions. The most common parasomnia s—non–rapid eye movement (NREM) sleep
arousal disorders and rapid eye movement (REM) sleep behavi or disorder—represent ad-
mixtures of wakefulness and NREM sleep an d wakefulness and REM sleep, respectively.
These conditions serve as a reminder that sleep and wakefulness are not mutually exclu-
sive and that sleep is not necessarily  a global, whole-brain phenomenon. 
Non–Rapid Eye Movement
Sleep Arousal Disorders
Diagnostic Criteria
A. Recurrent episodes of incomplete awakeni ng from sleep, usually occurring during the
first third of the major sleep episode, accompanied by either one of the following:
1.Sleepwalking:  Repeated episodes of rising from bed during sleep and walking
about. While sleepwalking, the individual has a blank, staring face; is relatively un-
responsive to the efforts of others to communicate with him or her; and can be
awakened only with great difficulty.
2.Sleep terrors:  Recurrent episodes of abrupt terror arousals from sleep, usually be-
ginning with a panicky scream. There is intense fear and signs of autonomic
arousal, such as mydriasis, tachycardia, rapid breathing, and sweating, during
each episode. There is relative unresponsiveness to efforts of others to comfort the
individual during the episodes.
B. No or little (e.g., only a single visual scene) dream imagery is recalled.
C. Amnesia for the episodes is present.