Another "addict" here.
FWIW, The Wife often dillutes our coffee cannister with 50 per cent "unleaded" ...
And, what no one has pointed out here yet, the shakes and/or movement are typically present with or without caffiene. The red dot sights and lasers just make it more obvious ...
Another FWIW ... A few weeks ago, I was scheduled for CHL instructor requalification at 7:30 A.M. !!! Like some others here, I am well beyond 40 (when eyes typically go south) and was concerned about needing to shoot well with a severe case of tendonitis (tennis elbow, altho I don't play) on strong side at the time.
So, following the advice of some medical-type friends, I bought a box of "BC Powder" (pain killer/anti-inflammatory) to get in my system early. I took one package the night before and two packages (yuk!) with a light breakfast (and a couple of cups of leaded coffee). Then, when time to shoot ... 250 of 250 with revolver. Ditto with the Glock.
Being quire pleased with the scores - and NOT having experienced much pain - I decided to put on the old reading glasses and check out the fine print on the box of BC Powder. IIRC, contents: 2/3 aspirin and 1/3 CAFFIENE.