By now I've read a lot of Sopranos re-caps and I'm kinda surprised that so few have brought up the Rozerem commercial. It's at the end, when AJ -- who starts the episode at home listening to Chamillionaire and, at the midpoint, gives the episode its title by reading Yeats -- is watching TV in the mental hospital. The spot is shown almost in its entirety along with AJ's reaction to it.
So: what does it mean? In a show defined by symbols -- or loose ends -- David Chase is that brilliant! -- it was funny to see a spot that is itself so filled with symbolism. And Lincoln, who previously appeared via Carm's Lincoln Log sandwiches. And sleep, which is all AJ has done and might ever do. Is it significant that AJ is watching this commercial or that Tony pulls him away from it? I don't know! But I'm pretty sure the important thing is: a commercial made its way into the Sopranos story! Yay!
ADDED: Now that I've watched this episode again, I noticed that it ends with the Italian lullaby Ninna Ninna. I think that means good night AJ.
MORE: Oh my. The song's liner notes (in PDF) are certainly interesting: "The mother sings to her little boy. His father, a brigand, escaped to the mountains....'Little Anton, I'd rather see you dead than a bandit in the mountains.' So that she will not have to disclose her husband's whereabouts, she too will go into the mountains. Her son sings: 'Mama, mama...I won't fall into dishonor.' In the third stanza the ghost-like voice of the father is heard....'all around me it's quiet and I only hear you singing.'"