Void Walker

A term used to describe someone who is currently in a depressed state, yet still seems to function almost entirely like a normal human would. The phrase was used in a study after one subject said his depression was an "abyss or a void that was slowly dragging (him) in, where (he) would finally die".
After the study, it was used by subjects to describe others in this "void" as a way of making them feel less alone even when they claim they are alienated by their own voids and abysses.