Arousals are frequent and associated with exacerbated blood pressure response in patients with primary hypertension.

Background: Spontaneous arousals are relatively common during sleep, and induce hemodynamic responses. We sought to investigate the frequency and magnitude of blood pressure (BP) increases triggered by spontaneous arousals in patients with primary hypertension.

Methods: We conducted a study in which we divided 18 nonobese, sedentary adults without sleep-disordered breathing into two groups, consisting of: (i) hypertensive (HT, n = 8) patients; and (ii) normotensive (NT, n = 10) controls. The groups were matched for age and body mass index. All subjects underwent full polysomnography with simultaneous monitoring of heart rate (HR) and beat-by-beat BP. Each subject's BP and HR were analyzed immediately before BP peaks triggered by spontaneous arousals during stage 2 of nonrapid eye movement sleep.

Results: The total sleep time, sleep efficiency, and sleep structure in the two study groups were similar. In contrast, the number of arousals was significantly higher in the HT than in the NT group, at 25 ± 5 vs. 12 ± 3 events/h, respectively (P < 0.05). The HR of the HT and NT groups was similar before arousal (65 ± 3 bpm vs. 67 ± 3 bpm, respectively, P < 0.01) and increased significantly and similarly in the two groups upon arousal (to 79 ± 6 bpm vs. 74 ± 4 bpm, respectively, P < 0.01). Systolic and diastolic BPs were significantly higher throughout sleep in the HT than in the NT group. During spontaneous arousals, BP increased in both groups (P < 0.05). However, the magnitude of the increase in systolic BP was significantly greater in the HT than in the NT group (22 ± 3 mm Hg vs. 15 ± 3 mm Hg, P < 0.05).

Conclusions: Patients with hypertension who do not have sleep-disordered breathing have an increased cardiovascular burden during sleep, which may be due to the greater number of arousals and exacerbated systolic BP response that they experience during sleep. These novel findings may have cardiovascular implications in patients with hypertension.