Deep Brain Stimulation (DBS) is an effective treatment for patients with advanced Parkinson's disease (PD) and motor complications whose condition can no longer be improved by adjustment of medical therapy. PD patients often report increased daily somnolence and night sleep abnormalities partially related to dopaminergic treatment. In a survey of 386 consecutive non-demented non-depressed PD patients seen in our clinic over a period of 3 months we found increased daily somnolence to be relatively uncommon in non-demented PD patients, although it may be associated with stable treatment with high dose dopamine agonists. Disease related factors seemed responsible for night sleep abnormalities. Because DBS of the subthalamic nucleus (STN) reduces motor disability, as well as total medication intake, one would expect a similar benefit on sleep abnormalities. Indeed, recent evidence suggests that chronic STN-DBS may improve sleep quality through increased nocturnal mobility and reduction of sleep fragmentation.