re: Weightlessness
Yes, indeed, many things get lost!!! I remember reading about this (first in disbelief) with Skylab.
For instance, if someone lets a pen float in front of him, moves his head (attention attracted by something else) and wants to take the pen again, the wind provoked by the head movement can induce a rotation to the pen and even though it's still very much there, he might not recognize it because it's no more in the same position it was.
To sleep, astronauts want to be attached because it gives a sensation of gravity. Also, being attached means not accidentally bumping on an equipment.