Like "Maybe your body is stopping you from crashing and dumping a bunch of glucose in your blood stream from your liver. I know doing jobs like that is really hard to keep any kind of schedule, but you may need to snack on some long lasting carbs such as nuts and fruit or something like a hard boiled egg. That keeps your body from thinking it has to give you energy to keep on going. It may not be that, it could be stress. It could be you are not drinking enough water. It could be you have contracted some kind of bug that has not manifested itself yet. Do you get a chance to take breaks more than just twice a day?"