Mother

»Sorry«, he said. »I was just tucking Mother in for the night. Sometimes she's apt to be a bit difficult.«
»You said she was ill. I would'nt want to disturb her.«
»Oh, you won't make any bother. She'll probably sleep like a baby.« Mr. Bates glanced over his shoulder at the stairway, then lowered his voice. »Actually, she's not sick, not physically, that is. But sometimes she gets these spells---«

From »Psycho«, Robert Bloch