The renin–angiotensin–aldosterone system (RAAS) regulates blood pressure through the vasoactive peptide angiotensin II [25] and recent evidence indicates that RAAS activity is progressively increased with increasing severity of OSA [26], but reduced following CPAP therapy. Increased RAAS activity promotes the genesis of a nondipping blood pressure profile [27] and blocking the RAAS with an angiotensin II receptor blocker is associated with restoration of a nocturnal dipping blood pressure pattern [28]. Thus, RAAS activation in OSA is implicated in the development of a nondipping blood pressure profile as well as the propagation of a more sustained hypertensive state.