Caffeine has different effects on me at different times; sometimes it makes me feel good and helps a bit with my depression, sometimes it makes me feel anxious and irritable, and sometimes it does almost nothing. I'm a bit of a caffeine addict, though I'm not consuming nearly as much as I used to, mainly because I'm often too broke to buy energy drinks, and I have almost no reason to as I'm unemployed. I usually have a couple cups of coffee a day, though even that's less than what I used to have, and I'm not drinking as much pop either.
Truth be told, caffeine used to be one of my special interests, and I was deeply fascinated by trying new energy drinks, comparing labels to see which brands and flavors had more caffeine than others, and of course seeing which ones had the best overall punch. A lot of this was motivated by a misguided attempt at "curing" my depression and brain fog, and making myself feel more motivated to accomplish things. I eventually realized that excess caffeine consumption was actually making me feel worse, and that brain fog and depression were just things I had to deal with as an aspie. Getting a job and learning to appreciate the value of the money I earned helped with this as well.