depression/anxiety/panic--vitamin deficiency

I've been up all night, and I'm so sick of being up and down ALL the time! I never feel healthy and normal anymore. I'm getting progressively more depressed (triggered by some minor perceived "rejections"), but I'm also getting to be really high-strung, and I've got my sleeping schedule so messed up.

I'm up til 6 or 7 in the morning, then I sleep til 3 or 4 in the afternoon, and I hate it. I feel like every word that comes out of my mouth is dumb, and that people just don't like me. This is a self-image problem, I realize, but it's accompanied by this really antsy, restless feeling (anxiety I suppose). I've had panic attacks in the past--all of them at night when I'm trying to go to sleep. I'll start to fall asleep, and then suddenly wake up feeling like I'd almost died. I get the whole chest-tightening, hands tingling, shallow breathing, thinking I'm going to die thing, and it continues sometimes the whole night, where I wake up several times at night with that same intense and senseless fear. I haven't had that lately, but I know I'm experiencing anxiety and starting to have problems with social situations.

I'm a vegetarian. Is there possibly a vitamin deficiency that might be part of the problem? I'm just starting grad school, so that may be partly to blame as well. I have already fallen behind, and that scares the hell out of me, especially since I have this complex about feeling like I'm not smart enough to be in these classes. If anyone can help me out, I'd REALLY appreciate it! I'm sick of being sick!