How do astronauts sleep on space station?

Expedition 55/56 flight engineer Ricky Arnold explains how astronauts grab some shut eye aboard the International Space Station. [How-tos in Space!](http://videos.space.com/m/rdSVVMs6/when-astronauts-have-to-go-bathrooms-in-space-explained-with-props?list=EoYEzhMC) Credit: NASA Johnson Space Center