Background: In adults, a siesta yields a blood pressure profile similar to that seen in nocturnal sleep. It is therefore stressed that siestas should not be included in daytime blood pressure measurement.
Objectives: To evaluate blood pressure profiles in pediatric and adolescent patients who reported a siesta during 24 h ambulatory blood pressure monitoring (ABPM).
Methods: Patients' diaries of actual sleep times were used to determine the periods of sleep (night-time and siesta) and daytime wakefulness. Ambulatory systolic and/or diastolic daytime and/or night-time hypertension was determined by comparing patients' measurements with normal values taken from published standards for healthy children and adolescents. Data obtained from 12 patients with ambulatory normotension and 12 patients with ambulatory hypertension, who were referred for an evaluation of hypertension or management of known hypertension, were analysed separately.
Results: Mean systolic (SBP) and diastolic (DBP) blood pressure values during the daytime awake period were significantly higher than the mean values for the period of daytime, including the siesta, both in patients with ambulatory normotension and in those with ambulatory hypertension (P<0.001 and P<0.01 for SBP and DBP, and P<0.001 and P<0.001 for SBP and DBP, respectively). The percentage night-time falls in SBP and DBP were 12.9+/-0.5 and 19.1+/-1.4 in patients with ambulatory normotension, and 7.1+/-1.5 and 12.9+/-2.2 in patients with ambulatory hypertension. These values were significantly higher when the siesta was excluded from the analysis in both groups (13.9+/-0.5% and 20.7+/-1.5%, P<0.001 and P<0.01 for SBP and DBP in patients with ambulatory normotension; 8+/-1.6% and 14.8+/-2.4%, P<0.001 and P<0.001 for SBP and DBP in patients with ambulatory hypertension, respectively).
Conclusions: By ignoring the effect of the siesta, both the calculation of daytime blood pressure values and the analysis of day-night variability in children and adolescents undergoing ABPM may be erroneously interpreted.