Hypertension is a common consequence of obstructive sleep apnea (OSA). However, not all individuals with OSA have hypertension and there are major individual differences in blood pressure response to positive airway pressure treatment of OSA. This project is focused on determining the basis of these individual differences in blood pressure response to OSA and will evaluate the possible underlying reasons for these differences. The results will help clinicians to know whether or not to expect a reduction in blood pressure (BP) to OSA treatment in a given patient and thereby personalize patient management.