Sleeping in space

A voyage to Mars would take about eight months on a modern spaceship. That might seem like a great opportunity to catch up on your sleep. But a recent experiment finds that people may develop sleep problems on a long space journey — or at least on the pretend trip in these tests.

“If we at some point really want to go to Mars and we want to send humans, then we need to know how they will cope,” Mathias Basner told Science News. He is a sleep researcher at the University of Pennsylvania’s Perelman School of Medicine in Philadelphia. His team published its new findings in early January.

Their experiment was like a long-running game of make-believe: Six men spent 520 days — a little more than 74 weeks — on a pretend voyage to Mars. In fact, the crew spent the entire time confined inside a small, windowless capsule in Moscow, Russia. The goal of this trial: to learn how people would cope with living in close quarters during travel to and from the Red Planet.

During their “trip,” the travelers pretended to land on Mars and to carry out science tests. Throughout the pretend trip, other scientists collected data on the travelers.

Each participant wore a device on his wrist. Once every minute, that device recorded the man’s motions. From these data, Basner’s team found that the volunteers were less active and slept more as the pretend mission continued. During the last 18.5 weeks of the trial, most participants were sleeping more each day than they had during the first 18.5 weeks.

Four of the men also developed sleep problems. One man’s natural sleep cycle shifted from a roughly 24-hour day to almost 25 hours long. (By coincidence, that time is closer to the length of a day on Mars.) This meant that he was sometimes awake when his crew members were asleep, and vice versa. Another one of the six pretend travelers slept less over time. Tests showed that he became less alert.

Messing with sleep can have serious consequences, says Jeffrey Sutton. He’s a doctor and scientist who worked on the study. He also directs the Center for Space Medicine at the Baylor College of Medicine in Houston.

“When you are doing high-risk behavior in space, a performance deficit can be life threatening,” he told Science News.

The decrease in activity found by Basner’s team could also prove problematic in space, says Sutton. Astronauts may need to increase their exercise to stay healthy.

Power Words

biomedicine Relating to both biology and medicine.

Mars A small, reddish planet, fourth from the sun. The shortest possible distance between Mars and Earth is about 56,000,000 km (35,000,000 miles).