There's something in Black Tea that regulates and stabilizes me, but I can't put my finger on what it is.

I've speculated it might be the Theanine content present in the tea, but I've had L-Theanine supplements, and they don't quite compare to a freshly prepared cup.

I feel more functional, able to switch between tasks more easily, able to relax more, am happier and feel at peace with everything when I regularly consume tea. Perhaps it is the Theanine or something else in the tea?