A Post-marketing Surveillance of the Negative Pressure Sleep Therapy System to Treat Obstructive Sleep Apnea

Inclusion Criteria: * 1\) Female or male adults with age between 18\~65 years old. (S1) * 2\) Non-obese patients with body mass index (BMI) \<29 kg/m2. (S1) * 3\) Patients able to read and sign on the informed consent form and able to comply with study requirements. (S1) * 4\) Patients able to be properly fitted\* with the oral interface as observed by the device feasibility test. (S1) * 5\) Patients with oxygen desaturation index (ODI) between 10\~40 (S2). * 6\) Patients with oral negative vacuum time maintained\* by iNAP® ≥4 hours/night and total sleep time (TST) ≥4 hours/night (S3). * iNAP® pressure more negative than -30 mmHg will be considered evidence of effective oral appliance application. * 7\) Patients with apnea-hypopnea index (AHI) between 10\~40 and TST ≥4 hours/night (Baseline PSG Night). * 8\) Patients with oral negative vacuum time maintained\* by iNAP® ≥4 hours/night and TST ≥4 hours/night (1st Tx PSG Night). * iNAP® pressure more negative than -30 mmHg will be considered evidence of effective oral appliance application. Exclusion Criteria: * 1\) Patients who are allergic to silicone. * 2\) Patients with obstructed nasal passages as evidenced by the inability to breathe through the nose with the mouth closed. * 3\) Patients who recently experienced a near-miss or prior automobile accident due to sleepiness. * 4\) Patients who have or have had hypoxemia (SpO2 \<80%) in the past six months caused by diseases other than OSA such as cardiac disease or severe pulmonary/respiratory disorders such as chronic obstructive pulmonary disease (COPD), interstitial lung disease, pneumothorax, pneumonia, etc. * 5\) Female patients who are lactating, pregnant or intend to become pregnant during the study period. * 6\) Patients with primary insomnia or any concomitant diagnosed or suspected sleep disorder. * 7\) Patients with muscle disease, central nervous disease or chronic neurological disorders, including central sleep apnea\*. * Central sleep apnea is defined as a central apnea index (CAI) ≥ 5/hr or if central sleep apnea accounts for ≥ 50% of the total AHI. * 8\) Patients in whom it is not suitable to use iNAP® in the opinion of the Investigator including, but not limited to, alcohol or substance abuse, loose teeth, missing teeth, or grinding teeth, completed deviated septum (Type IV or VII) or completed closed nostrils or advanced periodontal disease or tonsillar volumes greater than grade 3. * 9\) Patients with an inability to sleep through the night including, but not limited to, menopausal hot flashes, working at nights or rotating night shifts, planned travel across four or more time zones during the study period or within one week prior to study participation, or a sleep schedule not compatible with study site practices. * 10\) Patients with potential complications of sleep apnea that, in the opinion of the Investigator, may affect the study interpretation or the health or safety of the patients including, but not limited to, narcolepsy, restless leg syndrome, nasopharyngeal carcinoma (NPC), end stage renal failure, a history of severe cardiovascular disease (including New York Heart Association (NYHA) class III or IV cardiac failure, coronary artery disease with angina or myocardial infarction/stroke in the past six months, uncontrolled hypertension or hypotension or cardiac arrhythmias), unstable heart or renal transplantation or use of medicine or other treatment(s) that may confound the result of the study or pose additional risks to the patient, such as oral anticoagulants or other agents making patients prone to tongue hemorrhage. Stage II Inclusion Criteria: Patients who fulfill all the enrollment criteria of Stage I and whose treated AHI on the 1st Tx PSG Night is below 40.