I am so thirsty, but I'm not allowed to drink anything?

I am having my wisdom teeth removed at 10:30 in the morning. I woke up at around 3:00, around the time I usually do to get something to drink (I am ALWAYS thirsty for some reason), but I'm not allowed to eat or drink anything after midnight. I am really thirsty and I can't go back to sleep because of it. What should I do?