Adult Female Sleep During Hypoxic Bed Rest

Jeroen Van Cutsem; Nathalie Pattyn; Olivier Mairesse; Bérénice Delwiche; Helio Fernandez Tellez; Martine Van Puyvelde; Emilie Lacroix; Adam C McDonnell; Ola Eiken; Igor B Mekjavic

doi:10.3389/fnins.2022.852741

Adult Female Sleep During Hypoxic Bed Rest

Front Neurosci. 2022 May 10:16:852741. doi: 10.3389/fnins.2022.852741. eCollection 2022.

Authors

Jeroen Van Cutsem^{1

2}, Nathalie Pattyn^{1

2}, Olivier Mairesse^{3

4}, Bérénice Delwiche^{1

4}, Helio Fernandez Tellez¹, Martine Van Puyvelde^{1

5

6}, Emilie Lacroix¹, Adam C McDonnell⁷, Ola Eiken⁸, Igor B Mekjavic^{7

9}

Affiliations

¹ VIPER Research Unit, Royal Military Academy, Brussels, Belgium.
² Human Physiology and Sports Physiotherapy Research Group, Vrije Universiteit Brussel, Brussels, Belgium.
³ Sleep Laboratory and Unit for Chronobiology U78, Brugmann University Hospital, Vrije Universiteit Brussel, Brussels, Belgium.
⁴ Brain, Body and Cognition, Department of Psychology, Faculty of Psychology and Educational Sciences, Vrije Universiteit Brussel, Brussels, Belgium.
⁵ Experimental and Applied Psychology, Department of Psychology and Educational Sciences, Vrije Universiteit Brussel, Brussels, Belgium.
⁶ Clinical & Lifespan Psychology, Department of Psychology and Educational Sciences, Vrije Universiteit Brussel, Brussels, Belgium.
⁷ Department of Automation, Biocybernetics and Robotics, Jozef Stefan Institute, Ljubljana, Slovenia.
⁸ Department of Environmental Physiology, Swedish Aerospace Physiology centre, Royal Institute of Technology, Stockholm, Sweden.
⁹ Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, Canada.

Abstract

Purpose: Hypobaric hypoxic habitats are currently being touted as a potential solution to minimise decompression procedures in preparation for extra vehicular activities during future space missions. Since astronauts will live in hypoxic environments for the duration of such missions, the present study sought to elucidate the separate and combined effects of inactivity [simulated with the experimental bed rest (BR) model] and hypoxia on sleep characteristics in women.

Methods: Twelve women (Age = 27 ± 3 year) took part in three 10-day interventions, in a repeated measures cross-over counterbalanced design: (1) normobaric normoxic BR (NBR), (2) normobaric hypoxic BR (HBR; simulated altitude of 4,000 m), and (3) normobaric hypoxic ambulatory (HAMB; 4,000 m) confinement, during which sleep was assessed on night 1 and night 10 with polysomnography. In addition, one baseline sleep assessment was performed. This baseline assessment, although lacking a confinement aspect, was included statistically as a fourth comparison (i.e., pseudo normobaric normoxic ambulatory; pNAMB) in the present study.

Results: Hypoxia decreased sleep efficiency (p = 0.019), increased N1% sleep (p = 0.030), decreased N3 sleep duration (p = 0.003), and increased apnea hypopnea index (p < 0.001). BR impaired sleep maintenance, efficiency, and architecture [e.g., N2% sleep increased (p = 0.033)]. Specifically, for N3% sleep, the effects of partial pressure of oxygen and activity interacted. Hypoxia decreased N3% sleep both when active (pNAMB vs HAMB; p < 0.001) and inactive (NBR vs HBR; p = 0.021), however, this decrease was attenuated in the inactive state (-3.8%) compared to the active state (-10.2%).

Conclusion: A 10-day exposure to hypoxia and BR negatively impacted sleep on multiple levels as in macrostructure, microstructure and respiratory functioning. Interestingly, hypoxia appeared to have less adverse effects on sleep macrostructure while the participants were inactive (bed ridden) compared to when ambulatory. Data were missing to some extent (i.e., 20.8%). Therefore, multiple imputation was used, and our results should be considered as exploratory.

Keywords: altitude; bed rest; female; polysomnography; sex-specific differences; sleep.