I'm not sure "sleep-deprived" adequately describes Dylan during the 1966 period. Strung out (on heroin, mandrax, who knows . . . .) seems more accurate. Some of the film clips from "No Direction Home" show the guy totally effed up. It's a shame drugs got hold of him.
Just think of the inspirational songs he could have written. "How many roads must a man walk down" and stuff like that. Something to raise us up. Real anthems, not navel-gazing introspective paeans about his "conscious" exploding ("Visions of Johanna").
For crying out loud, he didn't even write a song about the assassination of Martin Luther King, but he writes laments for George Jackson, Hurricane Carter and Joey Gallo (and portrays them as no less than saints). I mean, what's wrong with this picture?