Always exhausted and in a haze, abnormal sleep. Anemia? Hypotension?

I should just see a doctor I know, but since i've been in college, no matter how much I sleep, I am always exhausted and in a mental haze. I can never seem to stop yawning. I also have abnormal sleep sometimes, where I will sleep for 13 hours, have extremely vivid dreams, and be even more tired, anxious, and out of it then usual. I also get extremely light headed after defecation sometimes. Low blood pressure? Oh yeah I also have very bad anxiety disorder and mild depression so I am on Klonapin and Cymbalta. Educated advice only please. P.s. I am only 21......why do I feel like I'm 50 and sick......