Anything with carbohydrate will have at least some potential of
supporting decay.  Anything non-caloric is probably OK (some will argue
the point with carbonated drinks--here there is still some potential for
problems depending on the acidity).  I don't know of any drinks that are
caloric that have no carbohydrate, so this is tough.  Something with
complex sugars will be less likely to cause decay IF it is cleared
quickly from the mouth.  Some energy drinks used by endurance athletes
get their calories from maltodextrin.  If there are no simple sugars
(glucose, fructose, maltose, etc.) or dissacharides the risk is probably
low, esp. if you rinse out well.
    You may also consider eating more but smaller meals, which may not only
place your last meal of the day closer to bedtime but is also likely to
keep your blood sugar on a more even keel, which is likely to decrease
your nocturnal cravings.

Steve