I never developed a taste for coffee, and decided early on that there was no reason to try to do so. (I'm in my late 30s now.) I do have the occasional coke, w

I never developed a taste for coffee, and decided early on that there was no reason to try to do so. (I'm in my late 30s now.) I do have the occasional coke, which I'd never noticed any effect from until the past few years. A single can of coke later than early afternoon now will have a noticeable impact on my sleep that night—get sleepy later, and end up sleeping around 0.5-1 hours less than I would otherwise. (With the expected resulting tiredness the next day.) Of course I expect much of that is due to lack of tolerance since I so rarely have caffeine.