What tea improves brain function?
You can also take Ginkgo Biloba. Wikipedia it. This supplement works wonders!
I don't know, but I could use about a ton of it!!!...;-)
The type of tea you like. :D I like Lipton Lemon Ice Tea! >D
Green tea, white tea, all varieties of positive organic flavors
Peace gave a great answer!
Anything with caffeine or a caffeine like stimulant will give you a temporary alert high. None will do this permanently.