It looks like my plan to switch from Irn Bru to Coke (or Pepsi) is a non-starter. Over the past several weeks we've been drinking fairly copious amounts of the stuff, largely because we've needed the sugar hit to counteract the extreme lack of sleep.
Unfortunately, the main effect of this has been to leave me twitchy and strung out, with a side order of not being able to sleep at night (though, of course, I could readily sleep during the day, when I ideally want to be awake...).
(I should also note: at one point, my go-to replacement would have been 7-up, that being another of the four drinks that didn't use artificial sweeteners. Alas, during the Christmas break I noticed that it, too, had changed over. Disturbingly, that change was made without any notice, which is rather concerning when you consider that a small number of people react to these things much more strongly than I do. Anyway, the net effect is that my choices are now Coke, Pepsi, or nothing.)
So it's no good. Once my stockpile of Irn Bru runs out, and unless Barrs come to their senses and bring back the original formula (which I'm losing hope of), I guess I really will have to just learn to go completely without.
(And, worryingly, I notice that some diluting juices (Ribena) are now also making use of artificial sweeteners. At this rate, I'll be down to water and nothing else.)