At the end of my first year in college I did the usual exam week cramming. I don't test well (my brain completely freezes up), so I had opted to write term papers instead of take exams whenever possible. Because I was given to procrastination, the papers weren't even close to completion on the second to last night. On the advice of a dormmate, I bought a packet of diet pills to help me stay awake all night. Back in 1980, there wasn't much in the diet pills besides lots and lots of caffeine. Along with other students in the dorm lounge, I popped two every four to six hours.
At 3am, everyone else in the dorm lounge was bright eyed and bushy-tailed, if somewhat exhausted. I picked up on this when I woke up from the snooze I'd fallen into an hour and a half before. This was a source of much amusement to the other lounge occupants, who had not dozed off and were talking and typing away a mile a minute. Granted, they crashed later on due to lack of sleep, but I was frustrated that I couldn't stay awake, despite dosing myself with caffeine.
Once I graduated and was in the workplace, I would get a Coke or Pepsi at 3pm breaktime like everyone else, hoping that it would give me energy to make it through the rest of the workday. It never worked, though, anymore than a morning cup of coffee did. So years later, when I was first diagnosed with ADHD and found out that it was treated with stimulants, I had one of those forehead-slapping moments. "So that's why caffeine never made me peppy."
Stimulants work differently on people with ADHD than with non-ADHD people. Instead of making us energetic and hyper, they calm us and help us focus. When I was first diagnosed, my mother said that she had been told that she probably was ADHD too. Given that she drinks a strong cup of tea right before bed to relax, I would say that makes sense. And I can have a cup of espresso with dinner at 8pm and be sleeping like a baby by 9:30pm.
I wish I could say that I inadvertently used caffeine over the three decades before I was diagnosed with ADHD to help calm and focus me, but unfortunately that wasn't the case. I'm willing to bet, however, that the diet pills I took when I was in college helped me to focus better and finish my work quicker, at least during the time that I was awake.
Paradoxically, I do have a cup of coffee most mornings, usually a Peet's mocha (I'm sorry Starbucks, but your coffee's just too bitter) but it's usually decaf. While caffeine doesn't give me energy, oddly enough, drinking it too frequently can make my heart race. My morning cup doesn't wake me up, but I like the taste, and I think I'm psychologically trained at this point to feel like it's part of my morning.