Sleep efficiency associated with nocturnal blood pressure and heart rate dipping in young adults. (883.1)

Abstract

Short sleep and fragmented sleep are associated with blunted nocturnal blood pressure (BP) dipping in humans. Despite epidemiological evidence that blunted nocturnal heart rate (HR) dipping is an independent risk factor for all‐cause mortality, the link between sleep efficiency and nocturnal HR dipping remains unclear. We hypothesized that subjects with low sleep efficiency (<85%) would have blunted nocturnal BP and HR dipping compared to subjects with high sleep efficiency (>85%). Twenty‐two normotensive subjects (13 men, 9 women; age 18‐28 years) wore an Actigraph watch for 7 days and nights, and an ambulatory BP monitor for 24 hours. There were no differences in age, sex, body mass index, mean sleep time, number of awakenings, or 24‐h blood pressure between the low (n=12) and high (n=10) sleep efficiency groups. However, the low sleep efficiency group demonstrated blunted dips in nocturnal systolic BP (9.9% vs. 14.2%, P=.04) and HR (12.4% vs. 21.4%, P=.03), as well as higher mean nocturnal HR (62.5 vs. 54.7 beats/min, P=.02), when compared to the high sleep efficiency group. In conclusion, our findings support growing evidence that sleep efficiency, independent of total sleep time, may be an important cardiovascular risk factor.