Wow -- what a coincidence. I was just about to post a question about this barking thing. Since January (when he came to live with me) Einstein has been VERY considerate about barking in the middle of the night. Lately, though, he's started barking at 1 am, or thereabouts. Could be a shift change for one of my neighbors -- causing Einstein to freak because there's someone stirring who isn't ordinarily stirring.
I have to say, by keeping my "calm-assertive" posture, smiling, using a soft touch, I praised Einstein for being such a good guard, loved on him and told him how beautiful he is, and asked him to please not bark anymore because I needed to sleep.
OMIGOD -- I swear he understood me. He came and laid right by the bed (for about 1/2 hour). I think the more calm and loving I am with him, the more devoted he becomes. I even asked him to lay down and he did it!
He definitely is an exception to Cesar's rule about Exercise, Discipline and Affection, in THAT order. He gets daily exercise, but the more affection he gets, the better our connection. (Reading Bones Falling (Raining?) from the Sky right now)