"The first night in space when I was drifting off to sleep," recalled one Apollo astronaut, "I suddenly realized that I had lost track of ... my arms and legs. For all my mind could tell, my limbs were not there. However, with a conscious command for an arm or leg to move, it instantly reappeared -- only to disappear again when I relaxed." Another astronaut from the Gemini program reported waking in the dark during …showed first 75 words of 1042 total…

…showed last 75 words of 1042 total…on different tricks to establish a common sense of "up". For example, all of the modules on the ISS will have a consistent "up" orientation. And the writing on the walls points in the same direction, too. Despite space sickness and occasional disorientation, living in space must also be a lot of fun! Fortunately, the brain quickly adapts. It learns to trust the eyes and reprograms signals from the vestibular system to reconcile the mismatch.