Non–Rapid Eye Movement Sleep Arousal Disorders 403
daytime sleepiness. In some individuals, a breathing-related sleep disorder may precipi-
tate episodes of sleepwalking.
REM sleep behavior disorder. REM sleep behavior disorder may be difficult to distin-
guish from NREM sleep arousal disorders. REM sleep behavior  disorder is characterized
by episodes of prominent, co mplex movements, often involving personal injury arising
from sleep. In contrast to NR EM sleep arousal disorders, REM  sleep behavior disorder oc-
curs during REM sleep. Individuals with REM sleep behavior disorder awaken easily and
report more detailed and vivid dream content than do individuals wi th NREM sleep arousal
disorders. They often report that they “act out dreams.” 
Parasomnia overlap syndrome. Parasomnia overlap syndrome consists of clinical and
polysomnographic features of both sleepwa lking and REM sleep behavior disorder.
Sleep-related seizures. Some types of seizures can prod uce episodes of very unusual
behaviors that occur predominantly or exclu sively during sleep. Nocturnal seizures may
closely mimic NREM sleep arousal  disorders but tend to be more stereotypic in nature, oc-
cur multiple times nightly, and be more likel y to occur from daytime naps. The presence of
sleep-related seizures does not preclude the presence of NREM sleep arousal disorders.
Sleep-related seizures should be classified as a form of epilepsy.
Alcohol-induced blackouts. Alcohol-induced blackouts may be associated with extremely
complex behaviors in the absence of other suggestions of intoxication. They do not involve
the loss of consciousness but rather reflect an isolated di sruption of memory for events
during a drinking episode. By history, these behaviors may be  indistinguishable from those
seen in NREM sleep arousal disorders.