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ISOLATION, SLEEP, COGNITION AND NEUROPHYSIOLOGICAL RESPONSES – AN INVESTIOGATION IN THE HUMAN EXPLORATION RESEARCH ANALOG (HERA)

Timo Klein1, 2*, Andrea Rossiter3, Jan Weber1, Tina Foitschik1, Brian Crucian4, Stefan Schneider1, 2 and Vera Abeln1
  • 1 German Sport University Cologne, Germany
  • 2 University of the Sunshine Coast, Australia
  • 3 King's College London, United Kingdom
  • 4 Johnson Space Center (NASA), United States

INTRODUCITON Space and isolation missions are known to be stressful for the human organism and negatively impact on the quality of sleep and mood of crewmembers. The maintenance of cognitive performance is of outmost importance for astronauts’ safety and for mission success during space travels. While short bouts of microgravity have been associated with greater cognitive performance than during gravitational conditions on earth (Wollseiffen et al., 2016), long-term isolation analogues on earth were linked with impaired cognitive performance (Basner et al., 2014; Gemignani et al., 2014). However, the underlying neurophysiological mechanisms remain unclear and efficient countermeasures are missing. Furthermore, high levels of stress are associated with a reduction of neurotropic factors like BDNF and IGF-1. This study aimed to investigate the effect of isolation on sleep, mood, cognition, neurotrophic factors and brain cortical activity during 30 days of isolation under space flight analogue conditions. METHODS Sixteen participants (aged: 37±7 years) were isolated in four missions, during each mission 4 participants stayed inside the HERA habitat at NASA for the duration of 30 days. Seventeen participants (aged: 32±9 years) were tested as a non-isolated control group simultaneously at the German Sport University Cologne. Both groups were asked to exercise on a daily basis during the 30 days of the interventions. Throughout the interventions participants wore wrist belt actigraphs to assess total light exposure during sleep, sleep efficiency and wake time after sleep onset (WASO). On mission days (MD) -5, 7, 28 and +5 participants completed a sleep diary and the Self-assessment questionnaire for Sleep and Awakening quality (SSA), the Positive Affect and Negative Affect Scale (PANAS-X) and cognitive tasks (speed match, chalkboard challenge, memory matrix by lumosity.com). Resting state brain activity as a marker of stress was assessed by a five-minutes resting electroencephalography in relaxed sitting position with eyes-closed (Brain Products, Munich). Also, intravenous morning cortisol, melatonin, BDNF and IGF-1 were assessed. Effects of the intervention (isolation vs. non-isolation) and time were determined using repeated measures ANOVA. RESULTS Cortisol level was significantly increased during isolation in comparison to non-isolated participants (p<0.01). Melatonin (p=0.37), BDNF (p=0.92) and IGF-1 (p=0.09) values showed no difference between the groups and remained unchanged during the mission. There were no group effects for total light exposure during sleep (p=0.61), sleep efficiency (p=0.54), WASO (p=0.73) and subjective sleep quality (SSA, p=0.10). Mood was also similar between the groups as there were no group by time interaction on the positive (p=0.38) and negative affect scale (p=0.20). Cognitive performance was not affected by isolation as no differences were shown between the groups (speed match, p=0.22; chalkboard challenge, p=0.75; memory matrix, p=0.29). Frontal cortical current density did not show any differences between the isolated and the non-isolated groups (p=0.40) and remained unchanged throughout the intervention as there was no group*time interaction (p=0.72). CONCLUSION During 30 days of isolation sleep, mood and cognition were not impaired although high levels of cortisol suggest increased levels of stress. The maintenance of sleep quality through a daily exercise routine during isolation might have positively affected CNS function and structural markers, as brain cortical activation and neurotropic factors were not impaired during isolation. Further results from HERA campagne 4 in 2017/2018 might allow further analyses and insights into possible effects of isolation on sleep, mood, cognition and its underlying neurophysiological mechanisms as well as the effect of physical activity as participants exercise less during isolation.

Acknowledgements

This study was supported by a grant from the German Ministry of Economic Affairs and Energy (BMWi) as handled by German Space Agency (DLR), grant No. 50WB1516 to Vera Abeln.

References

Basner, M., Dinges, D. F., Mollicone, D. J., Savelev, I., Ecker, A. J., Di Antonio, A., Jones, C. W., Hyder, E. C., Kan, K., Morukov, B. V., Sutton, J. P. (2014). Psychological and behavioral changes during confinement in a 520-day simulated interplanetary mission to mars. PLoS One, 9(3), e93298. doi: 10.1371/journal.pone.0093298 Gemignani, A., Piarulli, A., Menicucci, D., Laurino, M., Rota, G., Mastorci, F., Gushin, V., Shevchenko, O., Garbella, E., Pingitore, A., Sebastiani, L., Bergamasco, M., L'Abbate, A., Allegrini, P., Bedini, R. (2014). How stressful are 105 days of isolation? Sleep EEG patterns and tonic cortisol in healthy volunteers simulating manned flight to Mars. Int J Psychophysiol, 93(2), 211-219. doi: 10.1016/j.ijpsycho.2014.04.008 Wollseiffen, P., Vogt, T., Abeln, V., Struder, H. K., Askew, C. D., & Schneider, S. (2016). Neuro-cognitive performance is enhanced during short periods of microgravity. Physiol Behav, 155, 9-16. doi: 10.1016/j.physbeh.2015.11.036

Keywords: EEG, brain cortical activity, Exercise, Space flight analog, BDNF

Conference: 39th ISGP Meeting & ESA Life Sciences Meeting, Noordwijk, Netherlands, 18 Jun - 22 Jun, 2018.

Presentation Type: Extended abstract

Topic: Neurosciences and psychology

Citation: Klein T, Rossiter A, Weber J, Foitschik T, Crucian B, Schneider S and Abeln V (2019). ISOLATION, SLEEP, COGNITION AND NEUROPHYSIOLOGICAL RESPONSES – AN INVESTIOGATION IN THE HUMAN EXPLORATION RESEARCH ANALOG (HERA). Front. Physiol. Conference Abstract: 39th ISGP Meeting & ESA Life Sciences Meeting. doi: 10.3389/conf.fphys.2018.26.00045

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Received: 02 Dec 2018; Published Online: 16 Jan 2019.

* Correspondence: Mr. Timo Klein, German Sport University Cologne, Cologne, Germany, t.klein@dshs-koeln.de