I never thought to check heart rate, etc. But I can get killer headaches if I miss the morning tea. Drink tea, and it goes away.
We are addicted to many things, the air we breathe, try stopping that for more than a few minutes.
Seriously, yeah, the body
does build up "cravings" for tea, I am certain that some of the cravings for tea late at night ... thinking about morning sencha, etc, I am sure part of that is my body talking.
There are far worse things to be "addicted to."
I am not concerned about it, and I continue to drink tea every day virtually w/o fail. There are a lot of other things to worry about.