Astronauts returning from long ISS rotations consistently describe a half-step-outside-themselves sensation that flight surgeons recognize as part of the post-mission readjustment curve — a perceptual cost of spending six months in a body that had to learn a different world.
I feel it after a few minutes spent in a forest alone, so I would imagine it only gets worse in more extreme isolation.
There are no ducks in space to watch you… presumably…