Good tip. As someone who doesn't do well with coffee -- it makes me twitchy -- I find green tea helpful. I drink it several days a weak, in part for the general anti-oxidant health benefits, in part for the caffeine boost. But I feel like it sharpens my brain to use my available energy better, more effectively, so perhaps unlike most caffeine-consumers I tend to drink it only when I already feel fully rested. It doesn't seem to provide extra energy when my brain is already tired. In fact I fear in those cases it just prevents me from taking a quick nap which helps much much more to recover my brain energy. That's my experience with green tea so far -- I definitely want to explore it more.