Propranolol for Sleep Apnea Therapy

Inclusion Criteria: * History of OSA (AHI\>20, \>50% events obstructive) * Accustomed to CPAP use, and willing to discontinue CPAP temporarily for the study. * If the participant has already completed "Metabolic Impact of Intermittent CPAP" (NA\_00086830), they must have exhibited a \>10% increase in nocturnal FFA or glucose during CPAP Exclusion Criteria: * Cardiovascular risks * Decompensated congestive heart failure * Atrial fibrillation, sick sinus syndrome, 2nd or 3rd degree heart block, pacemaker implantation, Wolff-Parkinson-White Syndrome (if not known, will check on a screening EKG) * Uncontrolled hypertension \> 170/110 * History of postural hypotension. * Resting systolic pressure \<90 or heart rate \< 50 on screening visit * Drug interactions - currently taking any of the following drugs. (Subjects on these medications are excluded from participation and will not have the drug in question discontinued for the purposes of participation in the study. ) * Calcium channel blockers that reduce heart rate (diltiazem, verapamil, fendiline, gallopamil) * Sympatholytic drugs: any other beta blocker; clonidine, terazosin or doxazosin; reserpine * Anti-arrhythmic drugs: (e.g. amiodarone, sotalol, digoxin, quinidine, lidocaine, propafenone) * Coumadin (propranolol may prolong INR) * Drugs that Inhibit CYP2D6, CYP1A2, or CYP2C19: amiodarone, ciprofloxacin, cimetidine, delavirdine, fluconazole, fluoxetine, fluvoxamine, imipramine, isoniazid, paroxetine, quinidine, ritonavir, rizatriptan, teniposide, theophylline, tolbutamide, zileuton, zolmitriptan * Drugs that increase hepatic metabolism of propranolol: rifampin, ethanol, phenytoin, and phenobarbital * Neuroleptics/anxiolytics: (thioridazine, chlorpromazine - may increase propranolol level), haloperidol, valium * Illicit drugs such as cocaine or amphetamines. * Other medical conditions * Sleep disorder other than OSA, including: restless leg syndrome, parasomnia, or narcolepsy. * Shift work or circadian rhythm disorder that is expected to prevent good sleep as scheduled in the protocol * Insulin-dependent diabetes mellitus * Myasthenia gravis * Pheochromocytoma * Uncontrolled bronchospastic lung disease such as asthma or chronic obstructive pulmonary disease (COPD) * Current smoking * Chronic renal or liver failure * Known pregnancy, by urine testing in women of child-bearing age; nursing mothers * Known hypersensitivity to any beta blocker * History of falling asleep while driving, near miss * High risk occupation (pilot, commercial driver) Hemoglobin \< 10 g/dL on point of care screening