Patients with resistant hypertension (RH) are more likely to have reduced sleep duration and efficiency compared with normotensive individuals and those with controlled hypertension, a Canadian study suggests.

Oded Friedman, MD, and colleagues at the University of Toronto examined overnight polysomnographic results for 151 patients with obstructive sleep apnea (OSA) receiving care at Mount Sinai Hospital in Toronto. The group included 62 patients with RH, 49 with controlled hypertension, and 40 with normal BP. Subjects had OSA of equal severity.

On average, patients with RH slept 33.8 minutes less than those with controlled hypertension and 37.2 minutes less than those with normotension, after adjusting for differences in age, gender, BMI, apnea-hypopnea index, and diabetes, the investigators reported in the American Journal of Hypertension (2010;23:174-179).

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Sleep efficiency—which the researchers calculated as total sleep time expressed as a percentage of time spent in bed after lights out—was reduced by 7.9% and 10.2%, respectively. The RH group also spent 9.7 and 11.6 minutes less time in rapid eye movement (REM) sleep—the period during which dreams occur—compared with the controlled hypertension and normotension groups.

The researchers, who noted that experimentally induced sleep deprivation can elevate arterial pressure and worsen hypertension in human beings and animals, said the data from this study, together with their previous research, suggest that RH is associated with both OSA and with reduced sleep times and sleep efficiency compared with controlled hypertension and normotension.

“This underscores the possibility that short sleep time and poor sleep efficiency may contribute to the pathogenesis of RH through mechanisms yet to be identified,” the authors wrote.

The investigators defined RH as a clinic BP of 140/90 mm Hg or higher and a daytime BP 135/85 or higher on 24-hour ambulatory BP monitoring while adhering to three or more antihypertension medications at maximal or near-maximal doses (including a diuretic, unless contraindicated or intolerant), or as a BP below these levels while on four or more antihypertensive medications.