I have ADHD and have always just needed way more caffeine than most people. I usually have 20omg of caffeine two or three times a day when I’m working. I use those Celcius drink powders: zero calories with an energy blend. Meaningfully less caffeine than that in a serving makes me foggy. Red Bull 90mg of caffeine with sugar is molasses for my soul. I need 200mg caffeine with protein! I start the day with a meal, 200mg caffeine, 200mg CBG, and 300mg Welbutrin XL. I also have low blood pressure, and the caffeine helps me with that when waking up.