I have a new term for that feeling of being not awake enough to function: coffee-zombie.
While regular zombies seek living flesh to consume, coffee-zombies seek coffee or other caffeinated beverages. When observed in their natural habitat, coffee-zombies greatly resemble regular zombies in their shambling movements and relatively slow. Generally, coffee-zombies are less dangerous then regular zombies. If you bring a coffee-zombie their favored nourishment, it is possible that you can acquire one as a pet. Great caution must be exercised in bringing coffee-zombies their nourishment. If it is not delivered promptly upon giving indication it will be presented or if it is unavailable, coffee-zombies risk becoming a variant of regular zombies.