Recommended movies about the main character loosing their minds from the POV of the main character?

Examples would be stuff like Jacob's Ladder, Beau Is Afraid, and Saint Maude. Not really a horror film but in the same vain would be something like Synecdoche, New York. What I mean by "from the POV of the main character" is like in Jacob's Ladder, we see what he sees, and we experience the world the way he does throughout. Thank you!