Continuous Positive Airway Pressure, Arousability and Links to Mechanisms in Obstructive Sleep Apnea

Inclusion Criteria: * Able to provide informed consent. * Clinically confirmed new diagnosis of OSA: 1. Polysomnography AHI ≥ 10 per hour of sleep and/or 2. Home sleep apnea testing, respiratory even index, REI ≥ 10 per hour of recording Exclusion Criteria: * Known non-OSA related conditions associated with sleep-disordered breathing (e.g., a central disorder of hypersomnolence, neurological, neuromuscular, or pulmonary disorder) * Use of sleep-inducing medications (e.g., other non-benzodiazepine sedative hypnotic-drugs \[e.g., zoldpidem\], benzodiazepines, non-selective antihistamines, trazodone, opiates, barbituates) * Known hypersensitivity reaction to eszopiclone * Contraindications to its use based on medical history or function (e.g., dizziness at baseline or established mobility problems or imbalance) * History of complex sleep behaviors (e.g., NREM or REM parasomnias) * Concomitant use of ≥ 2 servings of alcohol per night or other CNS depressant for 2 weeks prior or throughout the study * Sleep opportunity of less than 7 hours * Severe active depression or other mental health disorders (e.g., schizophrenia, bipolar disorder, personality disorder). * History of sleep-walking, sleep-driving, and engaging in other activities while not fully awake * History of motor vehicle accidents related to sleepiness and/or motor vehicle "near misses" (e.g. sleepiness during driving or lane changes) * Severe hepatic impairment (liver function tests 2 X the upper limit of normal) * Unstable medical condition (e.g., decompensated heart failure, end-stage chronic obstructive pulmonary disease, end-stage renal disease) * Females of childbearing potential who are pregnant, breastfeeding, or intend to become pregnant, and women who are in the process of egg donation .