The Circadian Rhythms investigation examines the role of synchronized circadian rhythms and how it changes in astronauts during long duration space flight. More specifically, it addresses changes in the body composition and body temperature, as well as the effect of a non-24-hour light-dark cycle and reduced physical activity due to microgravity and an artificially controlled environment onboard the International Space Station (ISS). Understanding how such changes affect circadian rhythms enhances adaptation, performance and healthcare of future crewmembers.Principal Investigator(s)
European Space Agency (ESA)Sponsoring Organization
Information PendingResearch Benefits
Information PendingISS Expedition Duration:
May 2012 - September 2014Expeditions Assigned
31/32,33/34,35/36,37/38,39/40Previous ISS Missions
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. We hypothesize that long-term spaceflights 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, we aim to investigate the changes of core temperature profiles in humans during long-term spaceflight. Usually, 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
i) understand the time course and basic principles of the adaptations of the human autonomic nervous system in space,
ii) adjust more adequately physical exercise as well as rest- and work shifts, and
iii) foster adequate workplace illumination in the sense of occupational healthcare to humans in space.
The Circadian Rhythms investigation attempts to understand the time course and basic principles of the adaptations of the human autonomic nervous system in space. This understanding helps future crews to adequately adjust and schedule physical exercise, rest and work shifts in order to maximize productivity and minimize risks to health and wellbeing. Such data also helps vehicle designers and mission planners the ability to address questions of workplace illumination and occupational healthcare for humans during long-duration space missions. Results can also be compared to the 520 day MARS500 long-term sequestering experiment.Earth Applications
The Circadian Rhythms investigation attempts to understand the time course and basic principles of the adaptations of the human autonomic nervous system in space and therefore provides a unique setting by which to compare related autonomic nervous system disorders and shift work disorders here on Earth. Results can also be compared to data collected at the Georg-von-Neumayer Station in Antarctica.
Information PendingOperational Protocols