REM Parasomnias

The most common REM parasomnia is the nightmare. Nightmares are frightening awakenings from REM sleep associated with dream reports that are typically anxiety-laden. Stress of various kinds, and especially traumatic experiences, increases the frequency and severity of nightmares. Certain medications, including β-adrenergic blockers, and the withdrawal of REM suppressants can induce or increase the incidence of nightmares. Nightmares usually start between ages 3 and 6 years and affect 10%-50% of children in that age group severely enough to disturb their parents. Nightmares are easily differentiated from sleep terrors. Nightmares occur later in the night, usually in the last third of the sleep period, when REM sleep predominates. Nightmares characteristically are more organized, in terms of frightening dream reports, than sleep terrors. The child is fully awake and oriented when recounting a nightmare. The child usually has good recall of the nightmare in the morning. Nightmares also need to be differentiated from REM sleep behavior disorder described below. Treatment of nightmares consists of providing comfort at the time of occurrence and reducing precipitating daytime stressors when possible. For children with serious behavioral disruption associated with regularly recurring nightmares, often seen in association with acute or posttraumatic stress disorder, individual and/or family psychotherapy may be indicated.

REM sleep behavior disorder (Schenck et al. 1986) is characterized by the intermittent absence of the normal muscle inhibition of REM sleep and by the appearance of elaborate motor behaviors associated with dream mentation. Punching, kicking, leaping, and running from bed during an attempted dream enactment are typical manifestations. The behaviors usually correlate with reported dream imagery. REM sleep behavior disorder rarely occurs in childhood. More typically, it begins in late adulthood and may be associated with Parkinson's disease or dementia. In the few cases reported in childhood, a neurological lesion has been identified. A complete neurological evaluation, including brain imaging, is warranted. An evaluation in a sleep disorders center is also important. Excessive augmentation of submental electromyographic activation and exaggerated limb movements during REM sleep are observed polygraphically and on videotape. The beneficial response to clonazepam is impressive. Only case reports have been reported in childhood, but in one series of 55 adult patients treated with clonazepam, 76% of the patients responded favorably, with 88% of this group having a partial response and 12% having a substantial response (Mahowald and Schenck 1990).

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