cravings

I feel like i am doing okay for the most part without caffeine.
The thing that bothers me is that at the times of the day/week when I would normally consume a lot of caffeine, I still get headaches and I feel more tired than usual. My ability to concentrate decreases, and I sometimes gt a little irritable. The times are" Monday morning, Monday before class, Tuesday all friggin day, and Wednesday a couple hours before class. These are pretty much the times I need to concentrate most and I feel like just saying forget it and going back on the caffeine. I like the benefits, and I feel like there is always a ready cheap supply available, and that my use was fairly moderate to begin with (...could that be a bit on the irritability coming through?)
Anyway, let's see if I can concentrate enough to get by in class tonight.