Our group previously conducted a study looking at the performance of three styles of positive airway pressure masks during laboratory treatment studies for obstructive sleep apnea, and we found that patients using a full-mask mask required higher positive airway pressures than patients using nasal or nasal pillows style masks to achieve successful reduction of respiratory events. In the current study we want to randomly assign patients to either nasal or full-face masks and then switch to a different mask (if nasal was originally chosen than the mask will be switched to full-face and vise versa) after 3-weeks of use to see if the number of respiratory events change with the different mask style. We expect the number of respiratory events will increase with the use of full-face masks.

Inclusion Criteria:

• 18 years or older
• previously diagnosed with OSA
• returning for PAP titrations at the Center for Sleep Medicine
• CPAP and titration naive
• Must have a Apnea/Hypopnea Index (AHI) of ≥ 16/hr.

Exclusion Criteria:

• Patients with ≥ 50% central apneas