Variability of diurnal changes in ambulatory blood pressure and nocturnal dipping status in untreated hypertensive and normotensive subjects

An absent or diminished blood pressure (BP) fall during sleep (so-called "n ondipping") has been associated with a higher risk of cardiovascular compli cations, but the long-term reproducibility of dipper status and the relatio nship between diurnal changes in BP and perceived sleep quality have not be en previously documented in untreated hypertensive patients. Ambulatory BP (ABP) and dipping status were examined in 79 subjects (69 hypertensives and 10 normotensives) at 0, 6, and 12 months. Fifty-six percent of subjects ha d no change in their dipping status, the majority (53%) dipping normally on all three occasions. However, 44% of patients had variable dipping status, and normal nighttime dipping in BP was observed more often when patients p erceived their sleep quality to be good during the period of ABP recording. These results highlight significant intrasubject variability in the diurna l fluctuations in ABP and dipper status, which may in part reflect day-to-d ay variations in sleep disturbance during ABP monitoring. Classifying hyper tensive patients into dippers or nondippers on the basis of a single ABP re cording is unreliable and potentially misleading. Am J Hypertens 2000;13:10 35-1038 (C) 2000 American Journal of Hypertension, Ltd.