This is a Phase 3 Randomized Double-Blind Placebo-Controlled 6-month Parallel-Arm Study to Compare a Fixed Dose Combination of AD109 to Placebo in Obstructive Sleep Apnea.

Inclusion Criteria:

1. ≥18 years of age at the time of informed consent.
2. PSG criteria: AHI of ≥10 and ≤45; ≤ 25% central or mixed apneas; and PLM arousal index ≤15
3. PROMIS-Fatigue: raw score ≥17
4. PAP intolerance or current PAP refusal.
5. BMI between 18.5 and 40 kg/m2 for men, or 42 kg/m2 for women, inclusive.

Exclusion Criteria:

1. Narcolepsy, restless leg syndrome, REM sleep behavior disorder
2. Insomnia disorder characterized by difficulty initiating or maintaining sleep, or use within the past month of sedative-hypnotics or other medication for the purpose of treating or avoiding insomnia symptoms.
3. Pierre Robin, Treacher Collins, or other craniofacial malformation syndrome, or grade ≥3 tonsillar hypertrophy.
4. Clinically significant cardiac disease, e.g., ventricular arrhythmia, untreated or unstable coronary artery disease, cardiac failure. Stable atrial arrhythmia is allowed.
5. Neuromuscular disorder (e.g., motor neuron disease, muscular dystrophy or myopathy, myasthenic syndrome); epilepsy; Parkinson, Alzheimer, or other neurodegenerative disease.

Exclusion Criteria:

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