From Maybe I'm Dead by Joe Klaas.  You may know that Cotard Syndrome or Walking Corpse Syndrome is what psychiatrists call a delusion that one is already dead.  The thrice great Charles Fort had it [see our important post about that], as did the immortal Philip K. Dick.*  Thing is ... if this life actually does turn out to be a purgatorial realm, then those aware of being dead are the only ones not crazy.

*From Dick's Exegesis: "We are dead but don't know it, reliving our former lives but on tape (programmed), in a simulated world controlled by Valis the master entity or reality generator (like Brahman), where we relive in a virtually closed cycle again and again until we manage to add enough new good karma to trigger off divine intervention, which wakes us up and causes us to simultaneously both remember and forget, so that we can begin our reascent back up to our real home. This, then, is purgatorio, the afterlife, and we are under constant scrutiny and judgment, but don't know it, in a perfect simulation of the world we knew and remember -- v. Ubik and Lem's paradigm. We have for a long time been dying brains/souls slipping lower and lower through the realms, but the punishment of reliving this bottom-realm life is also an opportunity to add new good karma and break the vicious cycle of otherwise endless reliving of a portion of our former life. This, then, is the sophia summa of the six esoteric systems -- seven if you count alchemy -- of the entire world. Eight if you count hermeticism. We are dead, don't know it, and mechanically relive our life in a fake world until we get it right. Ma'at has judged us; we are punished, but we can change the balance... but we don't know we are here to do this, let alone know where we are. We must change the 'groove' for the better or just keep coming back, not remembering, not reascending."