Effect of Deep Brain Stimulation (DBS) on Sleep Architecture in Patients With Movement Disorders

Inclusion Criteria: * Prior DBS surgery for treatment of movement disorders such as PD, tremor, or dystonia. * Stable DBS stimulator settings and medication regimen for at least 6 weeks prior to the sleep studies. * Sleep dysfunction as measured by the Pittsburgh Sleep Quality Index (PSQI) (score \>5) at the subject's baseline pre-surgical evaluation. Exclusion Criteria: * Known narcolepsy * Other previous surgical treatment of Parkinson's disease, tremor, or dystonia (with the exception of DBS) including pallidotomy, thalamotomy, or gene therapy procedures. * Untreated obstructive sleep apnea. If obstructive sleep apnea is discovered during the first sleep study, the subject will be removed from the study. After they have been treated for at least 6 weeks with CPAP, they can re-start the study.