For a few years I drank 24 cans of Pepsi/day...
I used to drink 24 cans of Mountain Dew a day...
I recall when I was drinking the 18-20 cups of coffee per day (these were mugs, not the small actual measurement called a "cup") people would ask: "How do you get to sleep".
Well, it was never a problem. Looking back, I figure my body adapted and, as long as I poured in the caffeine, it was prepared to go pedal to the metal. I saw the effect when I was urged by my physician to cut back.
I figured I'd start by eliminating the full pot I always perked as soon as I got home from the office. The change was astounding. Without the continuing intake of caffeine, my body would shut down and I'd be out like a light by the end of the 6:00 news.
By the time I had reduced consumption to a few mugs per day, I found I didn't need to be "wired" to perform above specs. I think this all says something about how amazingly resilient the human body is.
Imagine going through all of that and just resetting to normal when it's over.