I had the same problem! Always tired and exhausted feeling, studying as much as I could but could never get as much done as I should. I was just recently diagnosed with generalized anxiety disorder. I have so many things racing in my mind to worry about, getting things done and getting quality sleep is a huge hurdle. I also felt that way when I had mono. If you feel sick/feverish I would recommend getting tested for mono (it's fairly common in people in high school and college). If you feel this way when you have a lot of stressors in your life, look into talking to a doctor about anxiety. Good luck to you!