Mars mission simulation reveals serious sleep problems

Posted by Kate Taylor

The data's in from the simulated Mars mission in which six trained astronauts were shut up for a year and a half. And it seems that long-term missions of this kind do indeed lead to problems for the crew.

The astronauts showed changes in sleep patterns and neurobehavioral consequences that researchers say will need to be addressed.

"The success of human interplanetary spaceflight, which is anticipated to be in this century, will depend on the ability of astronauts to remain confined and isolated from Earth much longer than previous missions or simulations," says David F Dinges of the Perelman School of Medicine. "This is the first investigation to pinpoint the crucial role that sleep-wake cycles will play in extended space missions."

The 520-day simulation kicked off on June 3, 2010 when the hatches were closed on a 550-cubic-meter IBMP spacecraft-like confinement facility in Russia. The simulated mission, involving an international, six-man team of volunteers, involved more than 90 experiments and realistic scenarios to gather psychological and medical data on the effects of a long-term deep space flight.

The mission was broken into three phases: 250 days for the trip to Mars, 30 days on the surface, and 240 days for the return to Earth.

The crew's rest-activity patterns were measured, along with performance and psychological responses to determine the extent to which sleep loss, fatigue, stress, mood changes and conflicts occurred during the mission.

A battery of different measurements included continuous recordings of body movements using wrist actigraphy, as well as light exposure and weekly computer-based neurobehavioral assessments to identify changes in the crew's activity levels, sleep quantity and quality, sleep-wake intervals, alertness performance, and workload throughout the 17 months of mission confinement.

And what this data reveals is that the crew became steadily less active through the mission, moving less while awake and sleeping more. Most of the crew members also experienced disturbances of sleep quality, alertness deficits, or altered sleep-wake intervals and timing, suggesting inadequate circadian synchronization.

"Taken together, these measurements point to the need to identify markers of differential vulnerability to abnormal decrease in muscular movement and sleep-wake changes in crew members during the prolonged isolation of exploration spaceflight and the need to ensure maintenance of the Earth's natural circadian rhythm, sleep quantity and quality, and optimal activity levels during exploration missions," says Mathias Basner of the University of Pennsylvania.

The team advises that crews on long missions should live in surface habitats that artificially mimic Earth's light exposure, food intake and exercise.