Positive Pressure Treatment of Obstructive Sleep Apnea

Inclusion Criteria: * Age 21 - 75 * Diagnosis of OSAHS with baseline AHI (Apnea-Hypopnea Index) equal or greater than 15 events/hr of sleep * Able and willing to provide written informed consent * Agreement to try PAP (positive airway pressure) as initial treatment approach * Adequate clinical CPAP titration within two weeks of enrollment Exclusion Criteria: * Participation in another interventional research study within the last 30 days * The need for more than one titration PSG (polysomnography) * The use of sedatives or hypnotics during the titration PSG * Major medical or psychiatric condition that would interfere with the demands of the study, adherence to PAP or the ability to commit to follow-up assessment. * Prior prescription for, or exposure to PAP therapy within the previous year (except exposure to CPAP during clinical therapy titration.) * Chronic respiratory failure or insufficiency with suspected or known neuromuscular disease, moderate or severe COPD (chronic obstructive pulmonary disease) or other pulmonary disorders, or any condition with an elevation of arterial carbon dioxide levels (\>45 mmHG) while awake or participants qualifying for oxygen therapy (arterial saturation \< or equal to 88% for more than five minutes). * Surgery of the upper airway, nose, sinus, or middle ear within the previous 90 days * Surgery at any time for the treatment of OSAHS such as uvulopalatopharyngoplasty (UPPP) * Presence of untreated or poorly managed, non-OSAHS related sleep disorders: * moderate to severe periodic limb movements (greater or equal to 15 per hour with symptoms or arousals) * Restless Leg syndrome (greater than 10 per hour) * Males experiencing chronic insomnia * Use of medications with hypnotic or sedative effects or regular use of night time sedatives or sleeping aids greater than or equal to one night per week. * Consumption of ethanol more than 4 nights per week (CAGE criteria) * Shift workers