I have a GRANDE LATTE from Starbucks every Week day around 5am when I walk my dog, get home at 6 feed him and eat myself and trade the Day. Caffeine has no effect on me....
I think it depends on how you are trading. If I'm trading the 1 minute charts and making quick trades then coffee does help my speed and focus. If I'm going long then I think coffee would help me plan ahead better, but does make me impatient.
I always have 2 cups of black coffee in the morning during market open hours. It helps me to keep my head clear. In the afternoon, I try to avoid consuming too much sweet stuff especially when my brain gets tired. Sweet stuff will make my head feels sleepy.
I start trading US markets about 3 PM local time. By then I usually had a quarter of a gallon coffee already. There was an article on the negative consequences of caffeine. There are positives too, of course, but you definitely can overdo it. I'm too fond of coffee to let it go.
Sounds like trading is deadly serious and stressful, it shouldn't be like that unless maybe there are other issues like bad health or stress from other causes. If you are fighting to survive and require 100% concentration on trading with coffee tipping you over the edge then rethink the trading system and methodology. Trading should be relatively relaxing and repetitive imo with not a lot of thought. Thought should go into the planning which means its done way beforehand, then all that's required it implementation when the circumstances are presented, no thinking, just do it.
%% 2 or 3 cups= helpful + enjoyable . 4 or 5 cups =hindrance. Sounds like you are sensitive to the stuff; wisdom is profitable to direct