With good green tea that has lots of it (shaded tea, but doesn't need to be gyokuro, Sencha Momiji is my favorite, cold brewed over night, then strained in a french press), I usually feel a slow but steady rise in wakefulness and around the time where I would start to get jittery (say, like when drinking a few too many cokes), it transitions over to an incredible calm mixed with a feeling of... wideness. Like your FOV is actually expanded by a few degrees, on many levels. Close your eyes and it feels like being at peace in a kind of Zen state. But... with a little buzz, very much an eager, productive peace where things line up and you can approach them.

It's probably different for different people, but I can highly recommend trying to "get some good stuff" to see whether it can do the same for you. I wouldn't want to miss it.