Research has found that when one drinks green tea the caffeine in green tea stimulates the whole body.
You can clear your mind in the morning by drinking green tea and body by drinking green tea in the afternoon. Most of the caffeine in green tea is extracted in the drying process of the leaves. Green tea caffeine is quite mild compared to other caffeinated beverages.
However, if you are sensitive to caffeine, you would be better off drinking your green tea weak.