The sleep thing is apparently significant. My AH had problems with it when he quit. And that was what he said he was dreading the most. He took Benadryl. I'm not suggesting that for anyone, it's just what he takes when he can't sleep. But a month later and he's much better. So hopefully your AH will have fewer troubles the more he lays off the booze. Xanax is a benzo, right? If I recall correctly, benzos are addictive. I have a prescription for Klonopin, which is a benzo. Does his doctor know he is an alcoholic?
Anyway, if I was having trouble going to sleep, my doctor gave me the option to either take my Klonopin before bed, or to take a sleep med (which I hated because it knocked me out too hard and too fast), or to take Benadryl (which is not addictive). I liked the Benadryl the best.