Looking for dark books where a person slowly goes insane due to hard work

Hi everyone,

I’m looking for recommendations for dark, psychologically heavy books where the main character gradually loses their sanity because of exhausting, overwhelming work or responsibilities.

I’m especially interested in stories where the mental breakdown feels realistic and slow — not something sudden, but a steady descent caused by pressure, isolation, routine, or impossible expectations.

It doesn’t matter if it’s classic literature, modern novels, or even something with a slight fantasy/sci-fi element — as long as the tone is bleak and the psychological aspect is strong.

Thanks in advance!