involved zipping oneself into a "sleeping bag" inside a compartment. The "sleeping bag" kept the astronaut from floating around without being overly restrictive. Although accomodations were sparse, none of the Skylab astronauts reported having trouble getting comfortable and/or with getting to sleep. And, since there is no "up" or "down" in space, at least one astronaut -- Alan Bean (second mission) in the picture below -- found that he prefered sleeping with his head toward the "floor" and his feet toward the "ceiling."