Have I just missed it or has no one posted Danial Johnston?

His entire catalog is the diary of a person truly going clinically insane.

anything by lee scratch perry, especially "super ape." it sounds like the dude is going / has gone insane while sitting under a palm tree smoking weed. if there's a good way to go insane, that's it.

"the madcap laughs" by syd barrett, there's another one

someone mentioned earth.... their music once infected me with tinnitus to such a degree that it brought me quite near the edge. but that's not the worst part.... the worst part is that their music is awesome, which means i persist in putting my ears through that.

Songs about cracking up are a Geto Boys staple. "Mind is Playin' Tricks on Me" or "Mind of a Lunatic" being the most obvious examples. "Diary of a Madman" from Scarface's Mr. Scarface is Back album was pretty solid as well.