Article

Sleep-Wake Differences in Heart Rate Variability During a 105-Day Simulated Mission to Mars

Departamento de Docencia e Investigación, Facultad de Ciencias Médicas, Universidad Católica Argentina, Buenos Aires.
Aviation Space and Environmental Medicine (Impact Factor: 0.78). 02/2012; 83(2):125-30. DOI: 10.3357/ASEM.3120.2012
Source: PubMed

ABSTRACT In prolonged spaceflights the effect of long-term confinement on the autonomic regulation of the heart is difficult to separate from the effect of prolonged exposure to microgravity or other space-related stressors. Our objective was to investigate whether the sleep-wake variations in the autonomic control of the heart are specifically altered by long-term confinement during the 105-d pilot study of the Earth-based Mars500 project.
Before (pre), during (T1: 30, T2: 70, andT3: 100 d), and after (post) confinement, 24-h EKG records were obtained from the six crewmembers that participated in the mission. Sleep and wake periods were determined by fitting a square wave to the data. Autonomic activity was evaluated through time and frequency domain indexes of heart rate variability (HRV) analysis during wake and sleep periods.
During confinement, wake HRV showed decreased mean heart rate and increased amplitude at all frequency levels, particularly in the very low (pre: 13.3 +/- 0.2; T1: 13.9 +/- 0.3; T2: 13.9 +/- 0.2; T3: 13.9 +/- 0.2; post: 13.2 +/- 0.2) and high (pre: 7.6 +/- 0.4; T1: 8.3 +/- 0.5; T2: 8.2 +/- 0.4; T3: 8.1 +/- 0.4; post: 7.6 +/- 0.3) frequency components (values expressed as mean +/- SE of wavelet power coefficients). Sleep HRV remained constant, while sleep-wake high frequency HRV differences diminished.
The observed autonomic changes during confinement reflect an increase in parasympathetic activity during wake periods. Several factors could account for this observation, including reduced daylight exposure related to the confinement situation.

0 Followers
 · 
115 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The objective was to check if 520 days in confinement (MARS 500), may affect the main peripheral arterial diameter and wall thickness and the main vein size. Common carotid (CC) femoral artery (FA) portal vein (PV), jugular (JG), femoral vein (FV) and tibial vein were assessed during MARS 500 by echography, performed by the subjects. A hand free volumic echographic capture method and a delayed 3D reconstruction software developed by our lab were used for collecting and measuring the vascular parameters. During the MARS 500 experiment the subjects performed 6 sessions among which 80% of the echographic data were of sufficient quality to be processed. No significant change was found for the Common carotid, Jugular vein, femoral artery, femoral vein, portal vein, and tibial vein diameter. CC and FA IMT (intima media thickness) were found significantly increased (14% to 28% P<0.05) in all the 6 subjects, during the confinement period and also at +2 days after the confinement period, but there was no significant difference 6 month later compare to pre MARS 500. The experiment confirmed that even untrained to performing echography the subjects were able to capture enough echographic data to reconstruct the vessel image from which the parameters were measured. The increase in both CC and FA IMT should be in relation with the stress generated by the confined environment or absence of solar radiation, as there was no change in gravity, temperature and air in the MARS 500 module, and minor changes in physical exercise and nutrition.
    PLoS ONE 01/2014; 9(1):e83063. DOI:10.1371/journal.pone.0083063 · 3.53 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The automatic computation of the hypnogram and sleep Parameters, from the data acquired with portable sensors, is a challenging problem with important clinical applications. In this paper, the hypnogram, the sleep efficiency (SE), rapid eye movement (REM), and nonREM (NREM) sleep percentages are automatically estimated from physiological (ECG and respiration) and behavioral (Actigraphy) nocturnal data. Two methods are described; the first deals with the problem of the hypnogram estimation and the second is specifically designed to compute the sleep parameters, outperforming the traditional estimation approach based on the hypnogram. Using an extended set of features the first method achieves an accuracy of 72.8%, 77.4%, and 80.3% in the detection of wakefulness, REM, and NREM states, respectively, and the second an estimation error of 4.3%, 9.8%, and 5.4% for the SE, REM, and NREM percentages, respectively.
    IEEE transactions on bio-medical engineering 06/2014; 61(6):1711-9. DOI:10.1109/TBME.2014.2301462 · 2.23 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Background: The Mars-105 project was aimed at simulating crew's activities, workload, and communication during a mission to Mars, evaluating the homeostatic adaptations to prolonged confinement and cohabitation. Methods: Fasting plasma glucose (FPG) and insulin, C-peptide, leptin, cortisol, and NGF and BDNF plasma levels were monitored in six healthy nonsmoking male subjects taking part in a 105-d Mars mission simulation. Samples were collected from each subject before (0 wk), during (2.5 wk; 5 wk; 10 wk; 15 wk), and after confinement (+1 wk). Results: Confinement resulted in impaired glucometabolic parameters, since FPG increased during the first 5 wk (baseline: 85.2 +/- 10.8 mg . dl(-1); 2.5 wk: 98.4 +/- 4.7 mg . dl(-1); 5 wk: 92.5 +/- 6.0 mg . dl(-1)) and insulin dropped at 2.5 wk (baseline: 14.4 +/- 4.8 mU . L-1; 2.5 wk: 7.7 +/- 2.1 mU . L-1), subsequently returning to baseline values. HOMA-IR paralleled plasma insulin, dropping to 1.8 +/- 0.5 at 2.5 wk (baseline: 3.0 +/- 1.2). At all time-points tested, plasma leptin levels were decreased (baseline: 4.4 +/- 3.3 ng . dl(-1); 2.5 wk: 1.6 +/- 1.2 ng . dl(-1); 5 wk: 1.3 +/- 0.8 ng . dl(-1); 10 wk: 1.5 +/- 1.1 ng . dl(-1); 15 wk:1.7 +/- 0.8 ng . dl(-1)), whereas cortisol levels were increased (baseline: 10.8 +/- 4.9 ng . dl(-1); 2.5 wk: 16.8 +/- 3.5 ng . dl(-1); 5 wk: 18.1 +/- 7.6 ng . dl(-1); 10 wk: 18.1 +/- 8.3 ng . dl(-1); 15 wk:14.2 +/- 4.4 ng . dl(-1)), resulting in a negative correlation between these hormones. BDNF levels increased only at 5 and 10 wk (baseline: 67.1 +/- 36.0 pg . ml(-1); 5 wk: 164 +/- 54 pg . ml(-1); and 10 wk: 110.2 +/- 28.9 pg . ml(-1)). Discussion: The data obtained with the Mars-105 experiment suggest that environmental stress has a strong impact upon metabolic and stress response, indicating the need for further studies and the implementation of specific countermeasures.
    Aviation Space and Environmental Medicine 08/2014; 85(8). DOI:10.3357/ASEM.3907.2014 · 0.78 Impact Factor

Full-text (2 Sources)

Download
51 Downloads
Available from
May 31, 2014