Sleep-Wake Differences in Scaling Behavior of the Human Heartbeat: Analysis of Terrestrial and Long-Term Space Flight Data

TL;DR

This study compares heartbeat dynamics during sleep and wakefulness across healthy individuals, cosmonauts, and heart disease patients, revealing sleep-related changes linked to neuroautonomic control, consistent across terrestrial and space environments.

Contribution

It demonstrates that sleep-wake differences in heartbeat scaling behavior are consistent across different populations and environments, highlighting intrinsic neuroautonomic regulation.

Findings

Greater anticorrelation in heartbeat fluctuations during sleep

Sleep-wake scaling differences are similar across groups

Differences are linked to neuroautonomic control, not activity level

Abstract

We compare scaling properties of the cardiac dynamics during sleep and wake periods for healthy individuals, cosmonauts during orbital flight, and subjects with severe heart disease. For all three groups, we find a greater degree of anticorrelation in the heartbeat fluctuations during sleep compared to wake periods. The sleep-wake difference in the scaling exponents for the three groups is comparable to the difference between healthy and diseased individuals. The observed scaling differences are not accounted for simply by different levels of activity, but appear related to intrinsic changes in the neuroautonomic control of the heartbeat.