How Do Astronauts Sleep In Space?
With their eyes closed (ha). And tied.
The photo above shows a group of astronauts sleeping (and preparing to sleep) aboard the Space Shuttle Atlantis. At the International Space Station, much more spacious, there is a little more privacy:
If you are interested in hearing from astronaut Chris Hadfield himself, follow the link in the photo above. But I can reconvey what he said — Onboard the ISS (International Space Station), there are six “dorms” like the one we see in the photo above. They are the size of a telephone booth, and inside each one, there is a sleeping bag tied to the wall, a pillow, a lamp, a fan, a laptop, and a compartment for personal effects.
As there is no feeling of heaviness inside the ISS, the pillow is expendable, despite being there. You can simply relax your body and sleep floating. This is why astronauts tie themselves up — they could wander around the station without realizing it otherwise.
Whoever decides to sleep outside their “dorms” can. Only the light is not turned off, so “outsiders” often wear sleeping masks and earplugs. It is curious to note that, despite having eight and a half hours available for sleep, most astronauts are satisfied with only six. This is probably due to the lack of weight in space: the body gets less tired than on Earth, recovering itself faster when sleeping.