Inclusion Criteria:  Ages 21-65 years old Men and women with a physician diagnosis of OSA (or strongly suspected to have sleep apnea - * see below) BMI 20 - 35 kg/m2  Exclusion Criteria:  Pregnancy (current or planned) Nursing Inability to provide self-consent or complete study procedures, such as questionnaires that are only available/validated in English. Already on effective therapy and adherent to treatment for OSA Other known untreated sleep fragmenting disorder, such as periodic limb movement disorder, or narcolepsy Circadian rhythm disorder Unrevascularized coronary artery disease, angina, prior heart attack or stroke, congestive heart failure Uncontrolled hypertension (systolic blood pressure >160, diastolic blood pressure >95) Chronic lung disease requiring the use of supplemental oxygen, or with evidence of hypercapnia due to obstructive lung disease. Presence of tracheostomy Hospitalization within the past 90 days Prior peptic ulcer disease, esophageal varices, or gastrointestinal bleeding (< 5 years) Prior gastric bypass surgery Chronic liver disease or end-stage kidney disease Active cancer Allergy to any of the study drug Regular use of medications known to affect control of breathing (opioids, sedatives/hypnotics including benzodiazepines, theophylline) Chronically using study drug (Eszopiclone) Active illicit substance use Alcohol use of >1 standard drink/night for women or >2 standard drinks/night for men nightly alcohol use Active smoking or vaping within the past 6 months Psychiatric disease, other than controlled depression/anxiety  Prisoners  Subjects who are strongly suspected to have sleep apnea will be offered an overnight home sleep apnea test (HSAT) to verify OSA diagnosis.