Effects of CPAP Therapy on Blood Pressure and Heart Rate Variability in Obstructive Sleep Apnea

Inclusion Criteria: * 30 to 75 years of age * Among patients with hypertension, no change in BP medication for at least 3 months. * Willing and able to give informed consent * Willing and able to complete ambulatory blood pressure monitoring at baseline and after 6-months. * Sleep study \[Polysomnography (PSG) or Home Sleep Apnea Study (HSAT) performed based on clinical grounds * 4% oxygen desaturation index (ODI4) ≥15 events/hour on clinical sleep study * Planned CPAP treatment by treating provider Exclusion Criteria: * Unable to apply BP cuff (e.g. arm circumference \>55 cm, prior breast cancer, structural abnormalities of the arm) * Current use of CPAP or Dental Device for OSA * Category III-IV of heart failure * Presence of Cheyne-Stokes Respiration (CSR) in PSG * Predominantly central sleep apnea (AHI≥15 events/hour) * Pregnancy * History of renal failure, or renal transplant * Self-reported sleep duration less than 5 hours per night on weeknights (work nights) * Other sleep disorders * Use of supplemental oxygen during wakefulness or sleep * Self-reported illicit drug use or marijuana use more than once per week * Unstable medical conditions: uncontrolled angina, uncontrolled hypertension, severe chronic obstructive pulmonary disease, active cancer, or unstable psychiatric disease * Any underlying condition that, in the opinion of the lead investigator, prohibits participation in the study * Development or adoption of any of the above exclusion criteria during the study period