"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 a mission and seeing a disembodied glow-in-the-dark watch floating in front of him.
Where had it come from? He realized moments later that the watch was around his own wrist. …