Noninvasive investigation of the body functional state during night sleep in microgravity

Irina Funtova,Roman Baevsky,Irina Slepchenkova,Еlena Luchitskaya,Аnna Chernikova

doi:10.12710/cardiometry.2014.5.5065

Abstract

The Sonocard experiment purpose was a noninvasive physiological signal recording from sleeping humans. In 2007-2012 the experiment was made by 22 Russian members of 17 missions to the International space station. Of the overall 302 experimental sessions 47 were performed pre, 215 in and 40 after flight. The seismographic technique was used to pick up cosmonaut’s body microoscillations induced by cardiac beats, respiration and motor activity. The flight Sonocard model is a midget device fitting into the T-shirt pocket. Heart rate variability analysis (HRV) was the major method of securing conclusive evidence on stress level and blood circulation autonomic regulation. We were first to trace reorganization of the autonomic regulation at the night time on different phases of long-duration space mission and pioneered a systematic investigation of the human body functional state during sleep. It was shown that in the absence of work loads and emotional stresses the central mechanisms of circulation regulation tend to increase their activities. The characteristic subsidence of breathing waves (HF) and growth of the vascular center (LF) portion within the HRV total spectrum by the end of flight were observed. Sleep quality in the course of long-duration missions was assessed. We succeeded in the first ever sleep assessment following operations in open space. The noninvasive physiological signal recording was recommended for use in spacecrew medical monitoring and ground-based experiments.

Highlights

Studies of the human sleep-wakefulness cycle in the unusual environment of long stay aboard space vehicles are of high practical significance
We should point out the possibility to assess sleep quality which is essential for judging about completeness of the functional reserve recovery and adjustment of cosmonaut’s work/rest cycle, if necessary
The series of investigations scheduled on the eve and soon after operations in open space showed the utility of this approach for estimating degree of organism straining and ability to recover, and energy cost of these operations [17]

Summary

Introduction

Studies of the human sleep-wakefulness cycle in the unusual environment of long stay aboard space vehicles are of high practical significance. Effects of microgravity per se can be studied in sleep only This being so, the theoretical aspect of the investigation implies filling the gap in the knowledge of microgravity effects on autonomic regulation of human physiological functions in the course of longduration mission. The practical aspect consists in exploring the possibility to assess sleep quality in microgravity and, effectiveness of the recovery process as staples of the human ability to work and functionality in general. In this context, it was crucial to develop a simple and comfortable procedure sleep studies other than present-day cumbersome polysomnography, which, because of placement of numerous sensors and electrodes and complex data analysis is unsuitable for the space flight environment

Methods

Results

Conclusion