However, as Prince Hamlet famously observed, sleep is not always untroubled. There is a group of phenomena known as parasomnias, unpleasant physical activities that can occur when someone is in a twilight state between deep sleep and wakefulness. I wondered if my patient might be suffering from one of these. Walking and talking in one’s sleep are parasomnias familiar to most people. But both of these occur in the lighter, NREM sleep and are not associated with dreaming. In fact, if you awaken sleepwalkers they will be confused and disoriented, demonstrating none of the vivid recall of dreams. In contrast, the frightening dreams that we call nightmares do occur in REM sleep. Though dramatic and often memorable, they are not normally associated with movement. From what he described, it seemed that my patient was neither dreamlessly sleepwalking nor lying motionless, trapped within a nightmare.
The only parasomnia associated with dreaming and movement is the uncommon neurologic condition known as REM sleep behavior disorder (RBD). While deep in REM sleep a patient with this disorder may kick, punch, or fling himself about while acting out his dreams. The dreams of patients with RBD often have aggressive content. Sleep partners may be injured or patients may hurt themselves, as my patient had done while diving for a line drive. Cases have been reported of patients choking their sleep partners in the context of defending themselves while dreaming about being attacked. Like Dr. Jekyll and Mr. Hyde, a patient with RBD may be mild mannered in the daytime (patients with this disorder typically are) but may utter profanities and commit violent, aggressive acts while dreaming. The episodes last several minutes.
To confirm my hunch that RBD was haunting my patient’s nights, I arranged for him to spend a night later that week in a sleep lab. He agreed, and as he lay dreaming, sensors over his muscles—in a test known as a polysomnogram—showed that the normal paralysis of REM sleep was being disrupted. Clearly he had RBD. Whatever violence was occurring in the couple’s bedroom was the result of a neurologic disorder.
The pioneering sleep researcher William Dement once said, “Dreaming permits each and every one of us to be quietly and safely insane every night of our lives.” But in REM sleep behavior disorder, the safety net has been rolled up and dreaming becomes risky. The exact cause of RBD is unknown, although it is often associated with degenerative neurological conditions. Also not known is why it occurs most frequently in older men. Fortunately, the disorder can be treated with a Valium-like medication called clonazepam.
The next day I reviewed the findings of the sleep study with my patient and his wife, explaining to them what was happening when he dreamed at night. I prescribed the medication, and once he started it the dream-associated activities stopped almost immediately. As long as he took his pill each night, he and his wife both slept better. Frankly, I slept better too, knowing that they were indeed the loving couple I had always thought them to be.
H. Lee Kagan is an internist in Los Angeles. Cases described in Vital Signs are real, but names and certain details have been changed.
