Analysis of Cardiorespiratory Variations During Sleep in Shift Workers by Univariate and Multivariate Detrended Fluctuation Analysis

This paper presents a study of the heart rate variability (HRV) and respiratory rate variability (RRV) during daytime and nighttime sleep, considering the sleep stages. Eleven healthy female shift workers of 20–54 years old, were recorded during the sleep period. Detrended fluctuation analysis (DFA) was used to assess the short and long-range correlations of time series. Furthermore, the bivariate signal (HRV - RRV) was evaluated by means of the multivariate DFA. The results showed significant differences between the sleep stages. Nevertheless, the mean values of the HRV and RRV exponents did not show meaningful variability between daytime and nighttime sleep. The results suggest that there are changes in the central nervous system, in the regulation of heart and respiratory rate during the sleep stages. Also, the correlations of nighttime sleep are preserved during daytime sleep, which could be due to the adaptability of sleep to changes due to shifting work, keeping correlation properties of HRV and RRV.