Key result
520-day confinement is linked to dampened circadian HRV rhythms and ~18% longer wake RR intervals.
Why the study?
The Mars500 project aimed to understand the psychological and physiological effects of prolonged confinement in an enclosed environment simulating a Mars mission, focusing on circadian heart rate variability.
Does confinement in an enclosed environment for 520 days alter the circadian profile of heart rate variability in crewmembers?
Observational (n=6)
Does confinement in an enclosed environment for 520 days alter the circadian profile of heart rate variability in crewmembers?
Long-term confinement in a simulated Mars mission dampens the circadian rhythm of autonomic cardiovascular control, potentially due to reduced daylight exposure and mood changes.
May signal need for autonomic monitoring in long-duration missions; leaves open effects on crew performance and health.
INTRODUCTION: The Mars500 project was conceived to gather knowledge about the psychological and physiological effects of living in an enclosed environment during 520 d as would be required for a real mission to Mars. Our objective was to investigate the circadian profile of heart rate variability (HRV) in the context of the Mars500 study. METHODS: Before, during, and after confinement, 24-h EKG records were obtained from the six crewmembers who participated in the mission. Autonomic activity was evaluated through time and frequency domain indexes of HRV analysis. Circadian rhythmicity was assessed both by averaging hourly HRV along wake and sleep scheduled periods and by fitting a 24-h harmonic to the hourly means. RESULTS: During confinement, wake HRV showed (mean +/- SE) a progressive increase in mean RR interval (from 778 +/- 24 ms to 916 +/- 42 ms), and in the amplitude (values are wavelet power coefficients) of very low (from 13.3 +/- 0.3 to 14.1 +/- 0.2) and high (from 7.8 +/- 0.4 to 8.3 +/- 0.3) frequency components. During sleep, the relative amplitude of the high frequency component of HRV decreased (from 11.8 +/- 1.6 to 9.4 +/- 1.8 normalized units). Overall, sleep-wake differences of HRV showed a progressive decrease of the relative amplitude of the high frequency component. Also, circadian HRV rhythms were dampened during confinement. DISCUSSION: Data revealed diminished amplitude of the rest-activity pattern of the autonomic nervous system parasympathetic function. Reduced daylight exposure and mood changes could account for this observation.
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Vigo et al. (2013) reported an observational. Confinement (Mars500 simulated mission) vs. Before confinement (baseline) was evaluated on Circadian profile of heart rate variability (HRV). During a 520-day simulated mission to Mars, confinement dampened circadian HRV rhythms and increased wake mean RR interval from 778 to 916 ms.
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