TeaChat

"A cup of tea can be stimulating or calming, depending on the brewing time up to 3 minutes stimulating, more than 3 minutes more calming)."

Taken from http://www.marx-computers.com/Tea/brew_tea.htm

Does it have something to do with more L-Theanine being released with longer brewing time?

yes L-theanine is said to be "relaxing"

also alot of this 3 minutes/time thing is based on the false claim that most caffeine is released in the first 1 minute.

but not just one thing increases with longer infusions
caffeine and other substances are released in greater amounts when steeped longer.
(since nobody measures chemical concentrations in every tea before its shipped, you don't know how much of whatever substance there is there in your tea.)

it will also depend how your own body responds to the combination.

Sounds like a load of BS to me.

If a and b are opposite states and some one claims that the same thing can cause a or b with different uses, they are probably BSing.