How do astronauts sleep in space?

In microgravity there is no up or down, so astronauts can sleep in any orientation, as long as they are secured. Each crew member on the ISS has a phone-box-sized sleeping station with a sleeping bag, a light, a laptop and space for personal items. Good ventilation is essential, because without air currents the carbon dioxide an astronaut breathes out can collect around their face. The station circles Earth about every 90 minutes, so the crew would see around 16 sunrises and sunsets a day; eye masks, window shades and carefully planned lighting help them keep a regular sleep schedule. Astronauts are typically scheduled for about eight and a half hours of sleep, though many report sleeping less.