Inclusion Criteria:  Age 50-80 years Ability to understand study procedures and to comply with them for the entire length of the study Ability to provide informed consent; Willing to accept random assignment to condition AHI ≥15 Individuals with who are unwilling or unable to adhere to CPAP Individuals who are adherent to CPAP therapy (i.e., 4 hours/night on 70%/nights over 30 days in the first 3 months of initial usage) Individuals who are adherent to mandibular advancement device each night Above-normal SBP (i.e., SBP ≥120) BMI ≤40 kg/m2 Weight stable in the prior 3 months (<3.0 kg weight change) and willing to remain weight stable throughout the study No change in anti-hypertensive medications or other medications (prescription or dosing) in the prior 3 months and willingness to maintain current medication regimen throughout the study Absence of unstable clinical disease as determined by medical history, physical examination, and blood chemistries Total cholesterol <240 mg/dL Fasting plasma glucose <300 mg/dL  Exclusion Criteria:  Age <50 or >80 years AHI <15 Individuals with central or mixed sleep disordered breathing Severe hypoxemia (<80% for >10% of recording time) during sleep ESS >15 SBP ≥160 or DBP ≥120 Current smoker Chronic overt and poorly controlled medical condition (e.g., diabetes, chronic kidney disease, cancer, congestive heart failure) Cheyne-Stokes Respiration Alcohol or illegal drug dependence or abuse Uncontrolled thyroid disease or change in thyroid medication within previous 3 months Regular/vigorous aerobic exercise (> 4 bouts/week, >30 min/bout at high workload >6 METS)