This story has one of those nifty titles that does a lot and means a lot in just a couple of words. The phrase "Sonny's blues" doesn't appear until the very end of the story, when the narrator is watching Sonny play at the club. But really, the whole story is about the blues that Sonny must battle as he struggles to recover from drug addiction. He has the blues from growing up in a tough Harlem neighborhood. He has the blues from trying to escape his childhood, from being frustrated as a musician, from the narrator's long silence even when he knew Sonny was hurting. This story is literally the story of Sonny's sadness.
But we think there might also be something else going on in the title, too. When it all comes down to it, Sonny is a musician. Playing the piano tortures him, drives him, and keeps him going all at the same time. Music is really Sonny's lifeblood. And the music he plays at the end of the story is "the blues." As Creole reminds Sonny and the rest of the musicians at the club, what they're playing is not happy music – it's soulful music, it's "blues" music. So, yes, the "blues" in the title might be about Sonny's emotions, but they might also refer to the music he plays. And for Sonny, these are really one and the same. Kinda cool how a two-word title can do all this, right?