Reliability of nocturnal blood pressure dipping

Increasing evidence documents the fact that individuals whose blood pressure drops or 'dips' relatively little at night have a higher risk of numerous cardiovascular illnesses. To examine the reliability of various measures of nocturnal blood pressure dipping. This study examined 17 individuals with ambulatory blood pressure monitoring on three 24 h recordings while they pursued a schedule similar to that of in-patients on a clinical research unit. Nocturnal dipping of blood pressure was scored three ways: as the drop in blood pressure between 10 p.m. and 6 a.m. ('clocktime'), as the drop in blood pressure tailored to each individual's reported bedtime ('bedtime'), and as the drop in blood pressure accompanying polysomnographically verified sleep ('sleeptime'). Adequate reliability was obtained for all three measures of dipping. There was, in general, a significant correlation across testing occasions (P