For me, there’s a uniquely difficult to find and ever changing line between not caffeinated enough to notice and “oh my god why is everything buzzing now I can’t think straight” when it comes to caffeine. Doesn’t matter if I’m drinking coffee, tea, or any other caffeinated drink. One sip too much and suddenly my ears are twitching uncontrollably, my heart is racing, and I can’t focus on anything productive. One day a cup of coffee is the sweet spot, the next day it’s two. Day three a glass of tea will throw me for a loop.