Patients with a clinically indicated sleep study will be enrolled in this study. They will have a diagnostic and a therapeutic sleep study with continuous positive airway pressure ventilation. For both studies a pH probe will be placed nasal to measure the amount of acidic reflux during each study. Baseline levels of reflux from the diagnostic sleep study will be compared to reflux episodes while on continuous positive airway pressure ventilation.

Inclusion Criteria:

• 18-75 years of age, symptoms consistent with sleep apnea, agree to consent form and placement of pH probes

Exclusion Criteria:

• any unstable medical condition, previous upper gi surgery or anatomic abnormality of upper gi tract, acid suppressing medication