Remember that mock mission to Mars? The scientific results are in, and they are not so great.
http://hosted.ap.org/dynamic/stories/U/ ... TE=DEFAULT
In a novel experiment, six volunteers were confined in a cramped mock spaceship in Moscow to simulate a 17-month voyage. It made most of the would-be spacemen lethargic, much like birds and bears heading into winter, gearing up for hibernation. [...] When leaving confinement in November 2011, the six volunteers - three Russians, a Frenchman, an Italian-Colombian and a Chinese - called their experience successful [...] The data scientists collected wasn't as rosy. Devices on the volunteers' wrists measured their movements and showed that when they were asleep and awake they were moving much less than they should have been, an unexpected and disturbing finding.
Former astronaut Michael Lopez-Alegria, who holds the American record for longest space mission, said he could relate to the study findings. During his 215 days in orbit on the space station, he sometimes had trouble getting back to sleep because he didn't have a sense of lying down or having his head on a pillow. The lack of sleep and lots of work caused him to sometimes nod off during the day, and the lack of gravity meant that when he fell asleep accidentally he would float away and awaken elsewhere in the station, he said.