Decker School of Nursing and Department of Anthropology, Binghamton University
Saturday All day, Plaza Level
Increased ambulatory blood pressure (BP) variability has been shown to be a risk factor for cardiovascular morbidity and mortality. We have previously reported that BP is significantly more variable during sleep than during the day in women, suggesting that sleep phase transitions may induce more variability than adaptational responses during the day. Whether the nocturnal elevation is reproducible, however, is unknown. This study assessed the persistence of elevated nocturnal BP variation over two weeks in women. The subjects were 71 women (age=34.9+7.7) of varying ethnicity who each wore an ambulatory BP monitor on a midweek workday on two separate days, two weeks apart. The women all worked in clerical or technical positions at a medical center in NYC. Ambulatory BP means and variation were determined at work, (11AM-3PM), home (6PM-10PM) and overnight (approx. 10PM-6AM). These parameters were compared by day and across the settings using two-way repeated- measures ANCOVA with BMI as a covariate. The results show that BP levels and variability were consistent over the two weeks, showing similar patterns across the settings. Work systolic and diastolic BP were consistently higher than sleep (p<.001), while the proportional BP variability (coefficient of variation) (CV) was consistently lower than sleep (p<.005). Home pressure levels were also persistently higher than sleep (p<.001), while the CV of diastolic BP was lower than sleep (p<.001). These findings suggest that nocturnal BP variation is persistently greater than that during the day and that this variation may be a key contributor to cardiovascular disease risk.
Supported by NIH grant HL47540.