[Sleep-arousal dissociation in a case of hypersomnia]

Dissociated sleep-arousal states are clinical and experimental phenomena which represent mixed forms of the three stages of this cycle (arousal, NREM sleep and REM sleep).

We describe the case of a man who presented with a history of excessive diurnal somnolence for the previous 5 years. He also had symptoms of sleep paralysis, hypnagogic hallucinations, automatic behavior and excessive movements during sleep. He had had no episodes of loss of muscle tone; MR was normal; HL DR2 and DQwl antigens were negative; two polisomnographic and a Multiple Latency Sleep test showed: 1. Absence of respiratory disorders. 2. Normal latency of REM sleep. 3. Periods of dissociated sleep (REM without atonia and arousal with atonia), and 4. An average sleep latency of 3.2 minutes and absence of REM periods.

This case adds a new type of dissociated sleep state which may accompany the disorder known as hypersomnia without REM periods.