The Mainichi Shimbun answers some common questions readers may have about life in space; specifically how one gets to sleep in low gravity settings.
Question: Astronaut Soichi Noguchi is spending about half a year on the International Space Station. But how do you sleep in space?
Answer: The space station has six small private spaces, each about the size of a telephone booth, where astronauts can sleep. There's no gravity, so they can sleep in any position, but to avoid floating around and bumping their heads, the astronauts sleep inside secured sleeping bags.
Q: Do they sleep for the same amount of time as they would on Earth?
A Basically it's the same. But the space station orbits the Earth at a rate of about 90 minutes per full rotation, so every 45 minutes it goes through morning and night. As a result, the astronauts base their sleeping times on Coordinated Universal Time (UTC), and turn in before 10 p.m. to wake up at around 6 a.m.
Q: Can they really sleep precisely to those times?
A: It seems like there are differences depending on the person. When astronaut Takuya Onishi spent an extended period on the space station in 2016, he would often "stay up late" until around midnight. There was also a report that 75% of American astronauts used sleeping medication while aboard. Conversely, some crew have reported sleeping better than they did on solid ground.
Q: Are six private spaces enough?
A: At present there are seven people on the space station, so one of the crew is currently sleeping in the cargo hold of the SpaceX Crew Dragon, which brought Noguchi and other astronauts to the space station.
Q: That's terrible, how did that happen?
A: Russia's Soyuz spacecraft, which had been used to send astronauts to the space station, could carry a maximum of three people. But the Crew Dragon can carry as many as seven, and the crew of four aboard its recent flight is too many for the space station's sleeping compartments.
Q: Is it quite unpleasant to lack sleep while in space?
A: There are plans in the near future for the Crew Dragon to be used in public space travel flights, and plans for a "space hotel" are also solidifying. It would be good if the research taking place on the space station could lead to the discovery of some kind of sleep mechanism in space that offers a pleasant environment for even ordinary people to take a rest when there.
(Japanese original by Tomohiro Ikeda, Science & Environment News Department)