I can definitely relate waking early to the levels of stress in your life at any given time. I have been going through a crisis over the last couple of months and have been waking early 3-5am. This has been despite my sedating medication, and attempts to stay up late in order to sleep.

What I have found is that the moment I wake up I start stressing that I cannot go back to sleep. I then go through the whole mental process of telling myself its ok to be awake and starting the relaxation therapy - concentrating on one group of muscles tensing and relaxing them etc etc. Trouble is by the time I do all of this I have actually woken myself up even more. Then the brain and the racing thoughts start and its game over. Once has the choice of either lying in bed for hours til the sun comes up or getting up and doing something productive like being on PC.

For me its stress related for sure, but for you it could also be medication related or something else not already mentioned. Be a good idea to bring it up when you have your next Pdoc review.