Matsumoto T, et al. - Since abnormalities in circadian blood pressure (BP) variation, especially increase in nocturnal BP, have been reported to be risk factors for cardiovascular disease, researchers performed a cross-sectional study to investigate possible correlations between sleep characteristics (including sleep fragmentation, sleep disordered breathing, and nocturia) and sleep BP by simultaneous multiday measurements. They found that, independently of the basic covariates, there was a link between a 3% oxygen desaturation index and the BP change, though the link was not significant after adjusting the fragmentation index. In addition, a strong and independent correlation was seen between frequency of urination and smaller nocturnal BP drop was observed among participants with frequent urination. Overall, subjective sleep approximations and frequent nocturnal urination may potentially confer risk for circadian BP abnormalities.