You shouldn't drink herbal tea unless you are trying to restore your condition, or you desperately need the calories/water from it.

Herbal tea's effect DOES NOT increase the amount of fatigue you recover during sleep.  All it does is increase condition recovery during sleep by 2% per hour, for six hours (1% on Interloper difficulty).



In addition, if you've just slept or are going to sleep, you'll probably have a full fatigue gague anyway, so the Cup of coffee's fatigue boost will be wasted.