Scientists recently developed the first commercially available absolute near-infrared oximeter, called OxiplexTS. This portable device will be used to study brain vascular autoregulatory responses (such as responses to hypoxia and hypercapnia) in persons with obstructive sleep apnea (OSA). These responses to allow for the assessment of brain vascular health. The OxiplexTS device will be beneficial in identifying persons at risk for cerebrovascular disease. Polysomnography (PSG), which is currently used to assess sleep disorders, gives important information on the function of different systems, however, it does not provide information on brain oxygenation and hemodynamics during sleep. The assessment of these factors, via NIRS, in persons with OSA is crucial because of the high prevalence of the disorder and the significant cardio/cerebrovascular health risk it represents.