Comment by rwyinuse

I think it still varies a lot between individuals. Caffeine often makes me more anxious, the effect on mental energy levels seems kind of random (either short burst of energy or just more tired mentally). Yet when I tried methylphenidate it made my mind calmer, clearly reduced anxiety and helped focus while increasing energy. At the same time it gave me pretty bad insomnia, stomach issues etc.

The best I can describe it is that I felt calmer in my mind, but overstimulated in my physical nervous system.