Time-varying limits for single blood pressures and heart rates of group-synchronized healthy women

The circadian waveform in blood pressure (BP) and heart rate (HR) was explored in young adult women. Clinically healthy nurses, 18-25 years of age, volunteered for this study. Each was to provide measurements of systolic, mean arterial, and diasolic BP and HR at 15-min intervals over 48 h by using an ambulatory monitor ABPM-630 (Colin Medical, Komaki, Japan). The data consist of several sets of values. One set consists of a series from each of 44 student nurses, monitored in November, 1987. A second set stems from 50 nurses studied in June, 1988. Another set is composed of data from 56 nurses monitored between May and September, 1989. The nurses were all on a diurnal activity/nocturnal rest schedule. Reference limits were computed as 90% prediction limits specified by circadian stage. Data in intervals of 1 h, displaced by 30 min were used for the computation of these limits. Examination of chronodesms, i.e., time-specified limits of acceptability, revealed that the limits were very rugged. Similar features were found for all sets of data, such as peaks after arising, around noon, and in the evening. The features may perhaps be related to a physiologic response rather than representing purely random variation.