Both dopamine agonists and levodopa may induce episodes termed "sleep attacks" in patients with PD. These episodes are well detailed behaviorally, but little is known about their neurophysiologic characterization. The authors performed a 24-hour polysomnography (PSG) in a PD patient taking pergolide in combination with levodopa, in which four of these diurnal sleep episodes occurred. PSG findings were followed up after pergolide withdrawal. Sleep episodes shared with narcolepsy both behavioral and EEG findings. However, pergolide partly restored a more physiologic sleep architecture, which was disrupted during therapy with levodopa alone.