Serious response, as I went through the same thing for an entire summer and fall.
For me, this was a sign of overtraining and undereating. I experienced the same symptoms as you. At first, it began with waking up in the middle of the night after about four hours of sleep and having to pee. No big deal, I could easily get back to sleep. This progressed to the point where I was waking up after only 2hrs of sleep having to urinate, going back to sleep, and repeating the process about 3 times over one night's sleep. And this was on a daily basis. I stopped drinking (water) within 4-5hrs of bed and got blood work done (everything normal).
During this time (following Spring college track season and into fall college xc season), I was pretty severly overtrained and undereating. My mileage was 80-90mpw for 2.5months during which time I was consuming about 1700-2000cals/day...way to little for a serious NCAA athlete. I dropped 7lbs over the period of 3months.
Now that I have gotten back to eating the necessary amount of food to provide my body with the energy it needs and regained a more natural and healthy weight, the problem has gone away. I no longer have these problems with sleep and on the occasions that I do, I find that it is after hard workouts or long run days where I might go to bed hungry.
Just my .02. This sort of thing really sucks and not only effects physical performance but also academic. I hope you can resolve the problem.