- having chronic symptoms as noted on screening symptom checklist. OSA diagnosis by the Sleep Clinic has been and is currently consistent with published consensus statements49 that CPAP treatment is indicated when the apnea-hypopnea index (AHI, number of apneas + hypopneas per hour of sleep) is either (1) greater than or equal to 15, or (2) between 5 and 15 AND accompanied by documented sleep apnea symptoms, including excessive daytime sleepiness, impaired cognition, mood disorders, insomnia, and documented cardiovascular diseases. Because mild OSA symptoms are at best modestly correlated with AHI, the research study will focus on patients with moderate to severe sleep apnea, and therefore inclusion criteria will require AHI > 15.