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

The primary objective of this study is to determine whether the effect of continuous positive airway pressure (CPAP) therapy on 24-hour mean blood pressure (BP) in patients with obstructive sleep apnea (OSA) varies between symptom phenotypes.

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