Sleeping in space is not easy thing. Some astronauts find it difficult to adapt themselves to weightlessness and in the beginning have to take sleeping pills. Later, however, everything becomes normal and their sleep is just as deep as that of any other healthy person after a hard day's work.
Physiologically the purpose of sleep is the same both in space and on Earth - to give rest to the brain and feed it with oxygen. In outer space due to weightlessness the blood rushes to the head, the vessels dilate and the process takes place faster. As a rule, sleep is of shorter duration in space. Although the daily routine provides for eight hours sleep, the astronauts fell well rested after six hours.
No beds are needed in spacecraft. The spaceship crew members rest in sleeping bags strapping themselves. Some prefer to sleep on the ceilin, because there is more room although in weightlessness the difference between floor and ceiling is relative.
During early flights in space orbital station Russian astronaut Vitali Sevastyanov noticed that, if your arms are free in sleep, they fold in front of the face by themselves and "float". Therefore, it is best to swaddle oneself like a baby. That is why the space crews are provided with sleeping bags.
When journalists ask astronauts about their dreams, they say they see only "earthly" dreams. Russian astronaut Valentin Lebedev, who was on a 211-day mission, admitted: "As a rule, neither in orbit, nor later on Earth did I see any dreams about space".