Reply to ‘Sleep duration and sleep blood pressure: the Nagahama Study’

Abstract

We used a timer-equipped BP monitor to measure sleep BP, whereas Abdalla et al. used ambulatory BP monitoring device. This methodological difference is not expected to cause a significant bias as the sleep BP measured by our method was reported to be equivalent to that measured using the ambulatory BP monitor [5]. Mean sleep duration of our study participants was approximately 1 h shorter than that of Abdalla et al. s participants. This is not surprising as it has been reported that Japanese have the shortest sleep time in the world [6]. However, as no linear correlation was found in the relationship between sleep duration categories and BP during sleep, the population differences in sleep duration might not be the reason for the disagreement of the results between the studies.To achieve perfect 24-h BP control, it is important to identify factors that influence BP during sleep. Our results underscore the importance of additional studies to clarify the relationship between sleep duration and sleep BP.