Variability in Sleep Patterns: an Emerging Risk Factor for Hypertension

Purpose of Review In this review, we summarize recent epidemiological data (2014-2019) that examine the association of sleep variability with blood pressure (BP), discuss potential underlying mechanisms, and highlight future research directions. Recent Findings Higher standard deviations of sleep duration and sleep-onset timing were not related to BP. However, a higher Sleep Regularity Index score was associated with lower odds of hypertension. Studies on social jetlag, a prevalent form of sleep variability, reported null associations. In contrast, lower interdaily stability in circadian rest-activity rhythms, a measure of invariability in sleep-wake cycles between days and synchronization to light and dark cycles, was associated with higher BP and greater hypertension odds, particularly among non-shift workers. Summary Sleep variability is consistently associated with risk factors for hypertension. Evidence on sleep variability and BP is limited and varies depending on the measure used to characterize day-to-day variability in sleep. Studies that identify and utilize a standard definition of sleep variability, incorporate a 24-h ambulatory BP monitoring, and ensure coinciding timing of sleep and BP measurements are necessary to disentangle these relationships.