Obstructive Sleep Apnea Therapy by Stimulation of the Hypoglossal Nerve

Inclusion Criteria: * Patient aged 18 to 80 years old * Patient with moderate to severe OSA based on an established diagnosis of OSA (15≤AHI\<65) by polysomnography or respiratory polygraphy not older thant three years. * Patient with moderate to severe OSA naïve of treatment or with difficulty accepting or adhering to CPAP treatment. * Willing and capable to have stimulation hardware permanently implanted, and to use the patient programmer to activate the stimulation * Willing and capable to return for all follow-up visits and conduct sleep studies at home, including the evaluation procedures and filling out questionnaires * Willing and capable of providing written informed consent. Exclusion Criteria: * Any anatomical finding that would compromise the performance of upper airway stimulation, such as the presence of complete concentric collapse of the soft palate * Have any condition or procedure that has compromised neurological control of the upper airway * Unable to operate the patient programmer * Pregnant or plan to become pregnant, and breastfeeding women * Require magnetic resonance imaging (MRI) * Have an implantable device that may be susceptible to unintended interaction with the Inspire system. Additional exclusions for study purposes only * Body Mass Index (BMI) of \>32 * Central + mixed apneas \> 25% of the total apnea-hypopnea index (AHI) * Neuromuscular disease * Hypoglossal-nerve palsy * Severe restrictive or obstructive pulmonary disease * Moderate-to-severe pulmonary arterial hypertension * Severe valvular heart disease * New York Heart Association class III or IV heart failure * Recent myocardial infarction or severe cardiac arrhythmias (within the past 6 months) * Persistent uncontrolled hypertension despite medication use * Coexisting nonrespiratory sleep disorders that would confound functional sleep assessment * Any chronic medical illness or condition that contraindicates a surgical procedure under general anesthesia, as judged by the clinical study Investigator * a terminal illness with life expectancy \< 12 months * Active psychiatric disease (psychotic illness, major depression, or acute anxiety attacks) which prevents subject compliance with the requirements of the investigational study testing * Radiotherapy or ablation therapy of the head and/or neck * Surgical resection for cancer or congenital malformations in the larynx, tongue, or throat(with exception of tonsillectomy and/or adenoidectomy) * Previous surgery within 3 months performed on the soft-palate tissue * Obvious fixed upper airway obstructions (tumors, polyps, unilateral nasal obstruction) * Need for chronic supplemental oxygen therapy for any other reason, pO2 (partial pressure of oxygen) \< 55 mm Hg * Clinical evidence of severe renal failure (Stage 4 or 5) undergoing dialysis or expected to institute dialysis within 6 months * Patients on medication that may alter consciousness, the pattern of respiration or sleep architecture (for example, benzodiazepiones, opiates, neuroleptics, prescription stimulants, phenothiazine, or any form of chemical substance abuse) * Patients taking blood thinning medications (for example warfarin, aspirin, plavix or other blood thinning agents which cannot be safety stopped or bridged temporarily to allow surgery to take place) * Any other reason for the investigator deems that the subject is unfit for participation in the study * Subject in exclusion period for another study * Subject under administrative or judicial control.