MRA Therapy Versus CPAP Therapy in Moderate OSAS

Inclusion Criteria: * Individuals who have been subjected to polysomnography and are diagnosed as having moderate (AHI 15-30) OSAS; * Aged ≥ 18 years; Exclusion Criteria: Medical and psychological criteria: * Patients previously treated for OSAS (e.g. CPAP, MRA); * Morphologic abnormalities of the upper airway (e.g., a compromised nasal passage, enlarged tonsils or adenoids, or upper airway soft-tissue or craniofacial abnormality); * Reported or documented unstable endocrine dysfunction (hypothyroidism, acromegaly, or pituitary adenoma); Reported or documented severe cardiovascular- or pulmonary co-morbidity * Clinically concurrent cardiovascular disease (coronary artery disease, heart failure,cardiac arrhythmias) * CVA within 6 months prior to randomisation * Daytime respiratory insufficiency * Severe Chronic Obstructive Pulmonary Disease (COPD) (GOLD 3 or 4; FEV1 / FVC \< 70% and FEV1 \< 50%); * Other diseases that may impact the evaluation of the results of the study according to the investigator's judgement. * Reported or documented psychological condition precluding informed consent (e.g., mental retardation, depression or schizophrenia); Whether the patient has unstable endocrine dysfunction, severe cardiovascular- or pulmonary co-morbidity or a psychological condition precluding informed consent, will be assessed by evaluating the patient's medical record. Dental exclusion criteria: * Extensive periodontal disease or tooth decay; * Active temporomandibular joint disease (including severe bruxism); * Restrictions in mouth opening (\< 25mm) or advancement of the mandible \<5mm); * Partial or complete edentulism (less than eight teeth in upper or lower jaw).