I believe a LOT of it has to do with depleted nutrients. Magnesium, calcium, essestial fatty acids and vit b and c all get severely depleted when alcohol is abused....especially over prolonged periods. All those nutrients (and there are more that the ones I listed) play a HUGE role in keeping those natural happy chemicals in the brain functioning properly. Anyhow, this is my understanding as belief. I began a nutritional program tailered to alcoholics and I cannot believe what a difference it made in stabilizing my mood and lowering my anxiety....not only that, I can sleep! I wouldnt have believed it if I hadnt done it myself. I did it with my doctors approval from the advice of a great book.