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

Abstract

U-shaped patterns are acceleration-deceleration periods in RR interval series. These relatively short time events (average duration 29.8±4.1 s) are the most laminar structures in the night-time recordings. The aim of this study is a analysis of sleep events occurring during U-shaped patterns in polysomnography (PSG) recordings obtained from Sleep Heart Health Study database. 500 PSG recordings were analyzed. U-shaped patterns were detected and categorized based on sleep stages, body position, respiratory events and EEG arousals. 4202 U-shaped patterns were found in 463 recordings. The majority of U-shaped patterns coincide with EEG arousals (73.9%). 48% of the patterns occurred at sleep phase changes. Most of the U-shaped patterns were associated with the Wake phase (61%). U-shaped patterns occurred at the position changes in 22.6% of cases. Analysis of respiratory events showed that Ushaped patterns occurred during hypopnea in 32.3% of the cases, CSA-1.7%, OSA-0.8% and desaturation-18.6%. The quantitative analysis of PSG recordings is a first step to discover the origin of the phenomenon of Ushaped patterns. These first observations show that the Ushaped patterns are strongly associated with EEG arousals and may play role in sleep regulation.