How do astronauts sleep in microgravity?

In microgravity, astronauts do not lie down in the usual sense because their bodies float freely. They typically sleep inside a sleeping bag secured to a wall, ceiling, or equipment rack to keep from drifting into objects. The International Space Station has crew quarters and quiet areas to reduce noise and light, although the station still experiences a roughly 90-minute day-night cycle as it orbits Earth. Astronaut sleep schedules are carefully managed because fatigue affects safety and performance during operations such as spacewalks and robotic work.