It has taken 2 years but (fingers crossed) I feel like I am finally back to normal. I sleep well, have no pain (other than normal for my age) and can have a few drinks without ill effects. I never believed it would take this long despite reading all the stories here. I even foolishly posted, after being off benzos for the requisite period to post a success story, that I was free. And I was free of the drug, but not the damage. I'll leave it to others to explain what happens to your brain, but I can't think of any other explanation for the experience than brain damage. I have seen so many specialists, and even a psychiatrist, trying to explain the daily morning pain and muscle fasciculations I've experienced over the last 2 years. Only one had an explanation that made sense - he said it sounds like you've had some brain trauma and brain injuries can take a very long time to heal. Looking back I can see the progress. Things did get incrementally better - just at a glacial pace. I left no stone unturned but, in the end, time was the healer. Toward the end, when things were definitely getting better, I tried for about 2 months CBD Oil and legal (here in the States) Delta 8 cannabis (a much mellower experience that regular cannabis). It did seem to me this sped up the healing but I would not be confident enough in that to say it as a fact.
It still boggles my mind how easily these drugs are prescribed. The psychiatrist I was referred to (after my doctor ran out of explanations) even tried to get me back on the benzos (which I emphatically refused). I see the drugs referenced in pop culture like they are no worse than weed or alcohol. I'm not going to say the drugs have no place in medicine but there most certainly needs to be more awareness of what kind of damage these drugs can exact on the brain in a short amount of time.
If you are starting your journey.... be kind to yourself, try to stay as active and involved in life as you can (it helps), stay positive and just realize that noticeable improvement may be measured in months, not weeks or days.