from my pre-
als experience hallucinations can simply be a sign of fatigue. i've done these ultra-marathon bicycle rides where we would ride for upwards of 24-hours pretty much non-stop. after midnight, after riding since before dawn, we'd "see" things that weren't there. i've heard the same from folks who do ultra-marathon canoe/kayaking. we knew those things we saw were not real, just momentary flights of fancy--kind of as though a sleepy mind gets lazy/sloppy in interpretating visual senses. so that may be all it is--just a need for a bit more rest, especially if the person seeing these things realizes that they are not real.