The ICSD recognizes more than 20 additional parasomnias not listed in DSM-IV. One of these conditions that has drawn clinical and research interest is REM sleep behavior disorder. This disorder is characterized by intermittent loss of muscle atonia during REM sleep, which results in excessive and often violent motor activity (Schenck et al. 1986). Movements (punching, kicking, trashing, falling out of bed) are usually sudden and may represent dream enactment triggered by the imagery of REM sleep. They may also be associated with emotionally charged utterances. When awakened from such episodes, the patient is usually alert, coherent, and reports a dream content consistent with the motoric activity.

REM sleep behavior disorder is associated with a significant potential for injuries to oneself or the bed partner. The disorder is more prevalent in late life, particularly in older men. It may also be drug induced or associated with a variety of neurological disorders. Psychopathology is generally not a contributing factor.

Behavioral/psychotherapeutic treatment As is the case with several parasomnias (e.g., sleepwalking), the main focus of behavioral interventions is prevention and safety. Several environmental changes may be required to secure a safer sleep environment and to prevent physical injuries. These measures would include sleeping on the ground floor; removing night tables, bedside dressers, lamps, or any dangerous objects near the bed or in the bedroom; and neutralizing weapons. Depending on the frequency of these episodes, the bed partner may need to sleep in a separate bedroom until the disorder is brought under control with drug treatment.

Pharmacological treatment Medications constitute the mainstay of treatment for REM sleep behavior disorder. Clonazepam, 0.5-2.0 mg at bedtime, is effective in suppressing behavioral episodes in approximately 90% of patients (Schenck and Mahowald 1996a, 1996b; Schenck et al. 1993a). Tolerance develops infrequently in clinical practice. Case reports suggest that carbamazepine, levodopa, and even TCAs may be helpful in treatment-resistant cases.