Mr. A was a 63-year-old man with a 41-year history of schizophrenia who was seen as an outpatient in a specialized clinic for schizophrenia. He had taken risperidone for several years but was switched to olanzapine, which was increased over 10 months to 20 mg at bedtime. After 1 week at this dose, he complained of sleepwalking most nights, during which no injuries occurred. The sleepwalking was witnessed by a roommate. Mr. A’s olanzapine dose was gradually decreased over 6 months, and he began taking risperidone. Even when he was taking only 5 mg of olanzapine, his sleepwalking persisted, but it ceased immediately when he stopped taking it. He reported no personal or family history of epilepsy, somnambulism, or other parasomnias. A computerized tomography scan of his head and EEG were normal. His other medications included valproate, 1750 mg/day, and procyclidine, 15 mg/day.
Ms. B was a 62-year-old woman with a 35-year history of schizophrenia who was being treated with loxapine. She started taking olanzapine and reached a maximum dose of 20 mg at bedtime. She then reported sleepwalking for 6 months. Valproate was added to her medication regimen, but her somnambulism persisted. She was switched from olanzapine to risperidone over 3 months; the somnambulism decreased in frequency with tapering doses and ceased after discontinuation of olanzapine.