I used to be really addicted to caffeine. I never even drank THAT much. At most I'd have 4 regular mugs. And back then it was usually 1/2 caff at my parent's house. But then I started also drinking green tea like 4 times a day and I remember I decided to quit both cold turkey because I had pretty bad acid reflux and was becoming just stupid in the mornings. I was ok until the 5th night I got a raging migraine. But I guess that was the breaking fever, so to speak, because after that I was fine. But it's a real addiction because I quit for about a year totally, didn't even do decaf, but I would crave it all the time. Eventually I started back up again, again it go to the point where I was feeling icky (again only drinking like 1-2 cups a day, I guess I'm a caffeine lightweight) and I quit. I now drink decaf only, but usually once a day. If I mix a bit of regular in it's usually ok.
But I wish they sold Dunkin Donuts flavor shots. I am going to try and find them somewhere. The kind without sugar. So good.