The purpose of this study is to determine the impact of sleep and breathing problems during sleep on memory, attention, and general well being (quality of life) in people with Parkinson Disease.

During the 2 year award period, we will prospectively enroll 200 patients with idiopathic Parkinson Disease (PD), who meet eligibility criteria below. All patients will undergo a baseline polysomnography (PSG) to diagnose Sleep Disordered Breathing (SDB) and will be asked to complete validated questionnaires to measure Sleep Quality, SDB risk, insomnia severity, daytime sleepiness, presence of restless leg syndrome (RLS), anxiety/depression, and quality of life. Medical records will be reviewed to determine co-morbidities and medication use. Each PD participant will undergo a full neurological examination, including the Unified Parkinson's Disease Rating Scale (UPDRS), the Hoehn & Yahr stage and a battery of neuro-cognitive measures at baseline. Patients with SDB will be offered PAP titration and treatment for 4 months. All patients (SDB [PAP compliant, non-compliant], and no SDB [controls]) will complete repeat neuro-cognitive evaluation, questionnaires, neurological evaluation and UPDRS assessment at 4 month and at 1 year follow-up. PD participants will be assessed in the "on" state in the morning. In the event that a participant goes "off" during testing, a break will be taken and participants will be given the option of taking their medication to return to the "on" state and resume testing or they can return later in the week to complete the evaluation. Although participants will understand the general purpose of the study, they will be blinded to the major study hypothesis. Neuropsychological examiners and the neurologist conducting the neurological exam will be blinded to the SDB status of the patient. Four month follow-up will be staggered according to enrolment date and will be completed by Year 2.

Inclusion Criteria:

• Able to give consent.
• ≥18 years and have a Hoehn and Yahr stage at the time of enrollment of ≤3, clinical diagnosis of idiopathic Parkinson's Disease meeting the United Kingdom Parkinson's Disease Society Brain Bank criteria.
• Stable medical condition, including medications in the 1 month prior to enrollment.

Exclusion Criteria:

• Previous diagnosis of SDB with active use of Positive Airway Pressure (PAP), surgery for SDB or tracheostomy.
• Inability to read and comprehend English and/or Spanish at a grade 5 level.
• Prior history of neurosurgical procedures for PD or any other condition.
• Diagnosis of dementia as defined by Mini-mental state examination (MMSE) of < 26.
• History of major uncontrolled psychiatric illness.
• History of drug or alcohol abuse/dependence.
• History of major head injury or other neurological disease.
• Patients with observable craniofacial abnormalities that may be a relative contraindication to PAP.