[dean177]

It sounds like you are reacting to the caffeine. Decaf still has somewhere between 5 and 20% the amount of caffeine as regular coffee

[amelius]

Yeah, this is what I thought at first. However, I can drink 2L of cola and still have no problems whatsoever.

Now that I think of it, I do feel bad one or two days after I stop drinking cola.

Perhaps it is the caffeine but it's acting in a different way, more like an addiction.