High Blood Pressure is a leading cause of stroke and heart attacks. Recently, we have come to understand the relationship of Sleep Apnea (stopping breathing while asleep) to elevations in blood pressure. In a recent study they found that 60% of patients with high blood pressure, being treated with three or more medications, still experiencing persistent elevations had undiagnosed Sleep Apnea. Normally, during sleep, blood pressure drops by 10 to 15 points. However, obstructed breathing at night causes low oxygen levels and repetitive arousals from sleep. As a result, the part of the nervous system called the sympathetic nervous system overreacts. The sympathetic nervous system constricts blood vessels, which raises blood pressure. Unfortunately, after a few years, these changes become chronic and persist during the day. As a result, many people with Sleep Apnea develop high blood pressure. Fortunately after treatment for Sleep Apnea, substantial drops in blood pressure occur and the associated risk of heart attack and stroke decrease. Taking care of Sleep Apnea can prevent and possibly cure High Blood Pressure.