Sleep disturbance during ambulatory blood pressure monitoring of hypertensive patients.
BACKGROUND: Hypertensive patients who fail to exhibit a normal fall in blood pressure at night may have a greater risk of target-organ damage. Sleep, with associated cessation of physical activity, is the principal determinant of nocturnal blood pressure 'dip'. OBJECTIVE: To ascertain whether hypertensive patients, who experience the discomfort of higher cuff-inflation pressures during ambulatory blood pressure monitoring, experience more interference with sleep, manifested by greater nocturnal physical activity. DESIGN: A retrospective case- control study. METHODS: Subjects were selected from a database of 475 patients who had undergone simultaneous 24 h ambulatory blood pressure monitoring and monitoring of physical activity with a wrist-mounted piezoelectric accelerometer. Sixty-one hypertensives (average daytime systolic blood pressure >/= 150 mmHg) were age matched to 61 subjects with average daytime systolic blood pressures </= 130 mmHg. RESULTS: Average daytime blood pressure was 161 +/- 8/95 +/- 10 mmHg in hypertensives and 123 +/- 6/81 +/- in normotensives; night-time blood pressures were 139 +/- 13/82 +/- 11 and 103 +/- 10/64 +/- 7 mmHg, respectively. Hypertensives exhibited higher nocturnal physical activity during sleeping time (2.46 +/- 2.16 versus 1.66 +/- 0.86 activity units, P =0.009) and from 0200 to 0500 h (2.43 +/- 3.12 versus 1.32 +/- 1.16 units, P = 0.011). Hypertensives fell asleep later (2359 h +/- 66 min versus 2335 h +/- 50 min, P = 0.027) slept less (8.00 +/- 1.27 h versus 8.26 +/- 1.08, NS) and had more episodes of nocturnal disturbance (4.74 +/- 3.42 versus 3.36 +/- 2.56, P = 0.004) than did normotensives. In addition, hypertensive subjects had a smaller nocturnal percentage rising single quote, left (low)dip' in blood pressure than did normotensive subjects (14 +/- 7/14 +/- 8 versus 16 +/- 7/21 +/- 7 mmHg, P = 0.03/P < 0.0001). CONCLUSIIONS: Higher cuff-inflation pressures experienced by hypertensive patients are associated with greater nocturnal physical activity and probably associated with poorer quality of sleep. Disturbance of sleep could influence 'dipper' status.
Leary
AC
Department of Pharmacology and Therapeutics, University College, Cork, Ireland.
Murphy
MB