Inclusion Criteria:

• Age 21 - 75
• Diagnosis of OSAHS with baseline AHI equal or greater than 15 events/hr of sleep
• Able and willing to provide written informed consent
• Agreement to try PAP 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
• 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 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