Inclusion Criteria:  Able to swallow trazodone capsules Stable pharmacological treatment of any other chronic conditions for at least 30 days prior to screening A diagnosis of mild cognitive impairment (MCI) A diagnosis of obstructive sleep apnea (OSA), and Apnea-Hypopnea Index > 5 Neuroimaging obtained during screening consistent with a clinical diagnosis of Alzheimer's disease (AD) and without findings of significant exclusionary abnormalities Written informed consent to participate in the study provided by the patient  Exclusion Criteria:  Diagnosis of dementia, neurodegenerative condition, seizure disorder or other infectious, metabolic, or systemic disease affecting the central nervous system Vitamin B12 or folate deficiency Diagnosis of mental health disorders Nootropic drugs except for AD prescriptions stable for at least 30 days Suspected or known allergy to trazodone Intake of drugs or substances potentially involved in clinically significant inhibition or induction of CYP34A or P-gp-medicate drug interactions with trazodone within 4 weeks or 5 half-lives of the interacting drug prior to administration of trazodone and throughout the course of the study Previous exposure to anti-Aβ vaccines Concurrent treatment with antipsychotic agents, antiepileptics centrally active antihypertensive drugs, sedatives, opioids, mood stabilizers, or benzodiazepines within 4 weeks of screening visit Patients who are receiving non-benzodiazepine hypnotics Clinically significant, advanced, or unstable disease that might interfere with outcome evaluations