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One of the characteristics of OSA is a nondipping nocturnal blood pressure profile. This likely results from heightened sympathetic drive during sleep, which is because of 4 main stimuli:(1) hypoxemia;(2) hypercapnia;(3) absence of lung inflation; and (4) microarousals at the end of apneic episodes. The cumulative effect of excess sympathetic activation, along with other vasoactive factors released in response to hypoxia (such as endothelin), may result in the daytime hypertension seen in these patients. However, even in the absence of daytime hypertension, sleep apnea patients may not exhibit the normal nocturnal dip in blood pressure during sleep because of apnea-induced sympathetic activation. Higher nocturnal blood pressure, independent of daytime hypertension, may play a significant role in the development of cardiovascular complications. 12 Thus, even in normotensive patients, a nocturnal nondipping …