A study based on Mars500 data revealed that the crew experienced increasing lethargy over the course of the mission, resulting in hypokinesis connected to sleep disturbances.
“The success of interplanetary human spaceflight will depend on many factors,” said biomedical and psychiatric researchers from the US and Russia who published the findings in the Proceedings of the National Academy of Sciences, “including the behavioral activity levels, sleep, and circadian timing of crews exposed to prolonged microgravity and confinement.”
In the Mars500 experiment, six volunteers were confined in a mock spaceship in Star City, Russia to simulate a 17-month journey to Mars and back. The high-fidelity ground simulation of a Mars mission was conducted to study the physical and psychological reactions of the crewmembers to isolation. The research used a number of continuous measurements including wrist actigraphy, light exposure, and weekly computer-based neurobehavioral assessments. The majority of crewmembers experienced issues connected to sleep quality resulting in a state of extended lethargy. Four had considerable trouble sleeping, with one having minor problems and the sixth mostly unaffected. It is still unknown if the men’s lethargy was just due to lack of sleep or was also caused by other factors such as lack of privacy, close quarters, or being away from their families for so long. Their state also led the crew to neglect exercise that will be extremely critical to maintaining physiological health on a long term zero gravity mission.
The loss of sleep is a crucial point in a Mars mission’s development. Astronauts will have to perform many and difficult tasks not only on their journey to Mars but also while they are on the Red Planet. Moreover there will be no real time communications with Earth, so these potentially tired and judgment-impaired astronauts will need to continually make decisions critical to their own survival.
Sleep quality is already a concern on the International Space Station where the noisy environment, microgravity, rapid solar cycle, and arrhythmic station maneuvers all contribute to less than ideal sleeping conditions. A new initiative to install blue-tinted LEDs in crew areas that can be used during rest times is expected to bring some improvements, starting with the first delivery of the lights in 2015.
The world record for continuous time in space is held by the cosmonaut Valery Polyakov, who lived on the Russian space station Mir for 14 months. In 2015, American astronaut Scott Kelly and Russian cosmonaut Mikhail Kornienko are scheduled to spend a whole year in space on the International Space Station.
Below, Mars500 crew members Diego Urbina explains a blue light experiment conducted near the end of their mission: