This is not my forum, but I thought I would tell you of my experience. I recently stopped drinking carbonated drinks all together, not only are most of them full of caffeine, but also sugar. When the caffeine and the sugar run out of your system, you crash a lot harder than you would normally.
Try fruit drinks or water, they keep your system clean, it's like running premium in your car and it runs a lot better.
Also, I know it is not always possible, but try to go to sleep early enough that your body can wake up on its own rather than depending on an alarm clock. If you do this and wake up before you would normally need to and feel pretty good, don't go back to sleep you will just wake up groggy and you will be tired all day.
sorry for preaching, that has just been my personal exp.