When we settle into our beds at night, we usually experience a pleasant sense of unburdening. After a long day of walking, sitting and standing, letting gravity do the work and sinking into a soft mattress can be a relief. But thousands of miles above the Earth, where astronauts live and work in zero gravity aboard the International Space Station (ISS), going to sleep in space presents a much different situation.
Since November 2000, the ISS has never been empty, with at most three astronauts living onboard. (After its completion, as many as six astronauts will stay there.) They stay up there for many months at a time, and their daily routine is widely varied. For instance, on May 19, 2008, the crew woke up at 6:00 a.m., and at 6:40 had a lengthy breakfast. At 9:30 the astronauts had a short telephone interview with the editor of Russian magazine "Cosmos," which was quickly followed by nearly three hours of exercise. After a lunch of prepared space food, the crew completed several tasks in between more exercise and another phone conference. By 8:00 p.m. they'd managed to finish dinner and squeeze in a private talk with their families.
After a busy day of exercising, spacewalking and research, the least an astronaut could ask for is a good night's sleep. But even the idea of "night" changes onboard a space shuttle, when an orbiter zooms around the Earth several times a day. And with the effects of microgravity and weightlessness, even the quality of sleep in space is different from that on Earth.
What's it like for astronauts to sleep in space? Do they just float around without anything to hold them down, or are they attached to something? Is it difficult to sleep in space, or do the effects of low gravity actually make it easier? To learn how astronauts get their Z's in zero gravity, read the next page.