Sleep RR-Interval U-patterns and Their Correlation to Movement Events

Abstract

The aim of this work is to investigate the relation between a phenomenon called "U-patterns" and their possible correlation to movement events in the context of sleep deprivation. U-patterns take place in the RR-interval time series during sleep. As their name suggests, these patterns present a U-shaped decrease-increase in RR-intervals, with a duration lasting from 20 to 40 seconds together with a minimum decrease of 15% in the local RR mean value.Over a span of 17 days, 15 healthy subjects (7males, 22.1 ± 1.7 yrs.) participated in a study of three subsequent stages. First, a baseline phase of seven days, during which the subjects slept normally. Immediately after, a sleep deprivation phase with a duration of three days, during which participants slept only three hours per night. Finally, in a 7-day recovery phase subjects went back to their normal baseline sleeping routine. Subjects underwent polysomnography (PSG) data acquisition while sleeping. U-patterns were extracted from RR-intervals while movement events were extracted from different PSG channels. Their relative temporal layout was studied to determine whether U-patterns are caused due to subject movement during sleep or vice versa. Results show that Upattern/movement events are correlated, always initiated by U-patterns with movement events terminating before the termination of their respective U-patterns.

U-shaped Patterns in HRV From a Polysomnographic Point of View: a Quantitative Analysis

“…It is not completely clear which physiological mechanisms trigger U-shaped patterns in humans. Yazdani et al using polysomnography recordings reported moderate correlation with movements during sleep [2]. In the literature we found many examples of acceleration-deceleration periods of RR time intervals during sleep associated with the sighs, leg movements, sleep apnea (i.e.…”

“…They are, in a domain of RR time intervals, the most laminar structures in nightrime recordings. They are defined as accelerationdeceleration periods in RR interval series, with duration between 20-40 s, and amplitude at smaller at least than 85% of the mean RR interval [1,2].…”

Reply to comment on ‘The effect of persistent U-shaped patterns in RR night-time series on the heart rate variability complexity in healthy humans’

“…In our article, we defined a U-shaped pattern as an acceleration-deceleration event, where the acceleration takes a longer time than the deceleration following it with a duration within 20-40 s and an amplitude smaller than 85% of the mean RR interval (similar criteria were used by Yazdani et al (2018Yazdani et al ( , 2019). In the Discussion section of the article, we showed that heart rate responses observed during sighs and periodic leg movements are shorter and weaker (in amplitude) than U-shaped patterns (see also Perez-Padilla et al (1983) and Winkelman (1999)).…”