Nocturia and night-time blood pressure: an association too frequently overlooked.

N octuria (defined as waking at night one or more times in order to void before returning to sleep) [1], represents a widespread condition that can negatively impact on the quality of sleep and overall health [2]. Nocturia may originate from factors that differ according to the three categories of nocturia: diurnal polyuria, nocturnal polyuria, and low nocturnal bladder capacity [3]. The prevalence of nocturia ranges from 11 to 93% when adopting the definition of one or more void per night, and from 2 to 61.5% according to the definition of two or more voids per night [4]. The prevalence increases with age. Moreover, although being often attributed to prostatic hypertrophy, nocturia is reported not only in men but also in women [4]. In younger populations, higher rates of nocturia were observed in women than in men, whereas in subjects older than 60 years, the reversed is the case [3]. Among the most obvious consequences of nocturia is sleep interruption, associated with lower sleep quality, which in turn reduces well being, vitality, productivity, and mental health [5]. More severe consequences of nocturia have also been reported. Data from the National Health and Nutrition Examination Survey III have shown that nocturia is a predictor of mortality. A metanalysis including about 30 000 subjects has shown that nocturia was associated with a 28% excess mortality risk per year [6].The increased mortality risk may be explained not only by the association of nocturia with several diseases, such as chronic kidney disease, heart failure, ischemic heart disease, and stroke but also diabetes and/or hypertension [7]. In hypertensive patients the prevalence of nocturia is higher than in normotensive individuals (34 vs. 24%) [8]. Although longitudinal evidence is limited, the relationship between nocturia and hypertension has been confirmed in several cross-sectional studies on general population samples [9] .One of them is the Multi-Ethnic Study of Atherosclerosis (MESA) study on community-living adults aged 60