First off, you are an inexperienced driver and it is going to take some time to build up to driving long periods of time without falling asleep. Energy drinks are the absolute worst thing you can do to help this! Its just a false sense of energy, followed by a huge crash afterwards and then a tolerance and dependence of your body to these things.
Stick with it, it will eventually get better! Until then, DON'T DRIVE TIRED!!! Pull over and get some rest even if you have been driving for only an hour! It isn't worth pushing yourself and killing someone, mainly yourself!