Rider Fatigue

[VNA]

You've got the wrong end of the stick.

No I hear what you are saying.  I'm just pointing out that the effect of a drink with caffeine in it depends on the dose.  Coke and Irn Bru have caffeine in them but not enougth to cause any dehydration effect, or give you much of a buzz unless you drink loads of it.

The tea and coffee on the boat is as you say absolutely fine, but having a mug of VNA's coffee before a dive probably wouldn't be the best idea.

Also like a lot of drugs, some people are more sensitive to it than others. 

And yes you are correct, the body gets used to it and likes it, it's very addictive.