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