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Core Temperature and Circadian Rhythms in Humans During Long-Term Space Flight (Circadian_Rhythms)
Principal Investigator
Research Area:
Clinical medicine
Species Studied
Scientific Name: Homo sapiens Species: Human

The circadian timing system (CTS) has been shown to be involved in the coordinated daily variation of almost every physiological and psychological system evaluated thus far. Maintaining synchronized circadian rhythms is important to health and well-being. The investigators hypothesize that long-term space flights significantly affect the synchronization of the circadian rhythm in humans due to changes in body composition, reduced physical activity, and/or changes of heat transfer, thermoregulation, and non-24-hour light-dark cycle in space. Therefore, the investigators aim to investigate the changes of core temperature profiles in humans during long-term space flight. Typically, 36 hour rectal temperature profiles are used to determine any changes associated with the CTS. However, such long-lasting continuous rectal temperature recordings are quite inconvenient for the subjects being investigated, especially during daily exercise and hygiene activities. Therefore, we recently introduced the double sensor, a new non-invasive heatflux method for determining body core temperature. The double sensor is located at the forehead and at the sternum/chest and allows continuous body core temperature measurements for extended periods of time.

Data on circadian rhythm obtained with the double sensor pre- in-, and post-flight shall be correlated with melatonin, which is one of the best-studied hormones following a classical circadian pattern. The results derived from the study might be useful to:

  1. understand the time course and basic principles of the adaptations of the human autonomic nervous system in space,
  2. adjust more adequately physical exercise as well as rest- and work shifts, and
  3. foster adequate workplace illumination in the sense of occupational healthcare to humans in space.

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Circadian rhythm

Data Information
Data Availability
Archiving in progress. Data is not yet available for this experiment.

Body electrical resistance
Body temperature
Body weight

Mission/Study Information
Mission Launch/Start Date Landing/End Date Duration
Expedition 32 07/01/2012 09/16/2012 78 days
Expedition 33 09/16/2012 11/18/2012 63 days
Expedition 34 11/18/2012 03/15/2013 117 days
Expedition 35 03/15/2013 05/13/2013 58 days
Expedition 36 05/13/2013 09/10/2013 166 days
Expedition 37 09/10/2013 11/10/2013 61 days
Expedition 38 11/10/2013 03/10/2014 120 days
Expedition 40 05/13/2014 09/10/2014 133 days
Expedition 41 09/10/2014 11/09/2014 29 days
Expedition 42 11/10/2014 03/11/2015 121 days
Expedition 43 03/11/2015 06/10/2015 91 days
Expedition 46 12/11/2015 03/02/2016 82 days
Expedition 47 03/02/2016 06/18/2016 108 days
Expedition 48 06/18/2016 09/06/2016 80 days
Expedition 49 09/06/2016 10/30/2016 54 days
Expedition 52 06/02/2017 09/02/2017 92 days
Expedition 53 09/02/2017 12/14/2017 102 days
Expedition 54 12/14/2017 02/27/2018 75 days
Expedition 55 02/27/2018 06/03/2018 96 days
Expedition 58 12/18/2018 03/14/2019 85 days
Expedition 59 03/14/2019 06/24/2019 102 days

Additional Information
Managing NASA Center
Johnson Space Center (JSC)
Responsible NASA Representative
Johnson Space Center LSDA Office
Project Manager: Jessica Keune
Institutional Support
European Space Agency (ESA)
Alternate Experiment Name
Proposal Date
Proposal Source