Ambulatory pulse pressure is a relatively sleep-independent variable

Objectives Characterization of sleep-induced pulse and mean arterial pressure (MAP) dip. Design Prospective study of consecutive referred patients. Setting Hypertension unit of community university hospital. Participants A total of 500 consecutive subjects referred to our unit for ambulatory blood pressure (BP) monitoring. There were 200 men and 300 women, the majority of which were treated hypertensives. Mean age was 59.7 +/- 16.6 years. Main outcome measures Effect of sleep on MAP and pulse pressure (PP). Results Twenty-four hour MAP was 98 +/- 10 mmHg. Awake and asleep MAPs were 101 +/- 11 and 87 +/- 11 mmHg, respectively. Twenty-four hour, awake and asleep pulse pressures were 60 +/- 13, 61 +/- 13 and 58 +/- 13 mmHg, respectively. MAP dip was 14%, 95% confidence interval (Cl) 13.4-14.6, whereas PP dip was 5%, 95% CI 4.1-5.8. Thus, the MAP dip was almost three times the PP dip (P < 0.0001). This held true for normotensives, hypertensives (treated and untreated), men, women and diabetic subjects. Conclusions Although pulse pressure is derived from BP, it is more stable during a 24-h period, with a lesser effect of sleep compared with MAP. This more rigid nature of the PP could explain its better prognostic value, compared to that of MAP.