Abstract-We investigated the relationship between the day-night blood pressure (BP) dip and the early morning BP surge in an cohort of 3012 initially untreated subjects with essential hypertension. The day-night reduction in systolic BP showed a direct association with the sleep trough (rϭ0.564; PϽ0.0001) and the preawakening (rϭ0.554; PϽ0.0001) systolic BP surge. Over a mean follow-up period of 8.44 years, 268 subjects developed a major cardiovascular event (composite of cardiovascular death, nonfatal myocardial infarction, nonfatal stroke, and heart failure requiring hospitalization) and 220 subjects died. In a Cox model, after adjustment for predictive covariates, including age, sex, diabetes mellitus, cigarette smoking, total cholesterol, left ventricular hypertrophy on ECG, estimated glomerular filtration rate, and average 24-hour systolic BP, a blunted sleep trough (Յ19.5 mm Hg; quartile 1) and preawakening (Յ9.5 mm Hg; quartile 1) BP surge was associated with an excess risk of events (hazard ratio, 1.66 [95% CI, 1.14 -2.42]; Pϭ0.009; hazard ratio, 1.71 [95% CI, 1.12-2.71]; Pϭ0.013). After adjustment for the same covariates, neither the dipping pattern nor the measures of early morning BP surge were independent predictors of mortality. In conclusion, in initially untreated subjects with hypertension, a blunted day-night BP dip was associated with a blunted morning BP surge and vice versa. In these subjects, a blunted morning BP surge was an independent predictor of cardiovascular events, whereas an excessive BP surge did not portend an increased risk of events. (Hypertension. 2012;60:34-42.)Key Words: hypertension Ⅲ dippers Ⅲ nondippers Ⅲ blood pressure monitoring Ⅲ sleep Ⅲ morning blood pressure surge Ⅲ ambulatory blood pressure O ccurrence of major cardiovascular complications, including myocardial infarction (MI), 1 stroke, 2 and sudden cardiac death, 3 peaks in the early morning hours, typically in the first 4 to 6 hours after awakening. Therefore, the hypothesis has been raised that the extent of blood pressure (BP) surge in the early morning may be associated with the risk of cardiovascular complications. This hypothesis is potentially relevant because it might imply the possibility that reducing the early morning rise in BP may lower the risk of major events that occur in the early morning. By using 24-hour ambulatory BP (ABP) monitoring in cohorts of hypertensive patients 4-6 or randomized samples from the general population, 7,8 several investigators examined the association between the morning BP surge and the subsequent outcome, but results were not univocal. On the other hand, many studies showed that the risk of cardiovascular disease directly increases with nighttime BP and a blunted BP dip from day to night. 6,[9][10][11][12] The adverse prognostic impact of a blunted or reversed diurnal BP rhythm seems difficult to reconcile with the hypothesis that an excessive rise in BP from the nighttime period to the early morning is also predictive of a worse outcome. None of the studies that addresse...