At the Matrix Institute on Addiction where I see some clients, they call this "The Wall" suggesting that it usually comes right after a relatively easy period of recovery in which clients are self-assured and confident that they've got their addiction beat. "The Wall" is supposed to be marked by anhedonia, depression, severe cravings, irritability, and more fun stuff like that. After the wall is the promised land of long-term recovery. By identifying the specific stages of recovery addicts are supposed to gain more understanding of their process and experience less shame. I love the Matrix method, but I see things a little differently.  The way I see it, "The Wall" is far from a single point in time, but is instead part of a larger pattern I like to call Rubber-band Recovery.

Rubber-Band Recovery in Addiction

I'm sure everyone reading this has at some point played with a rubber band, stretching it and letting it snap back to its original state or pulling it between two fingers and playing it like a string (another name for this approach could be String Recovery, but that might get confused with theoretical physics and we don't want that). When pulling the rubber-band one way, its internal structure pulls back, trying to get back to its natural state. The body can be thought to do the same when placed under chronic alcohol and drug use in addiction - it has a slew of internal processes that work hard to keep the body in its natural state, at homeostasis. Naturally, due to the pharmacological mechanisms of alcohol, cocaine, methamphetamine, marijuana, and many other drugs, these systems usually fail at setting everything back to normal especially during the use itself, which is why we get high. However, their work in a body that consumes drugs on a regular basis is obvious - reductions in the production of specific chemicals (like relevant neurotransmitters), changes in the structure of the brain itself (like producing less receptors or even removing some from the brain's cells), and production of chemicals that combat the drugs' actions.

All in all, the body and brain of a long-time, chronic, heavy user of alcohol and drugs are different from the body and brain they started with in important ways that specifically relate to their alcohol and drug use. They are like the stretched rubber band, similar but obviously not the same as it was in its relaxed state.