College, Stress, and Mental Illness?

So we've all seen the articles, read the statistics. It always seems that the amount of depression and the increased stress from a non-stop schedule is no doubt related. It makes me wonder what the demands of college are doing to today's students. All-nighters, piles of homework, midterms, finals, ah! Yeah, I've been there. Actually I am there right now as mid-semester hits hard. I've got more work that I can handle, tests to study for that will be incredibly difficult, staying up late studying, getting up early the cram some more before jumping into a full day of classes. Come the end of the week, I am absolutely exhausted. But anyway, enough about me, I know I'm not alone.
My main point here is that the demands of college plus all the rest of life piled on top a likely breaking us. I could probably go look for some statistics if you please, but right now I'm just speculating. So who is to blame? The professors? Do they ask to much of students? Well in some cases, I'd like to scream yes, its all their fault, but in reality they are just doing their job. To them their class is the only class, though they probably can remember what undergrad was like, so I can not put the blame to them. It does however make one wonder whether professors should keep in mind their class is not the only one a student likely has and that we are of course not supernatural. Being a physics student I'd like to scream in frustration every time I hear the phrase "when your bored sometime, derive this....", "practice extra problems" and other variations. WITH WHAT TIME?!
Perhaps it is that all majors are not created equal. I know it is a common assumption to believe the sciences to be much harder than the arts. Perhaps indeed this is true. Or is it that we all are under similar amounts of stress? This I can't answer without being bias. I would definitely trade a day just to see if music is as hard as physics. So what is going on here? Should colleges being keep the heat high, so as to weed out as much as possible, at all possible costs? Do, we, the students have a right to understand, to learn, without sacrificing our health in order to get there. Where is the balancing point? Or should their even be such a thing?
These are just some things that I ponder when I reach that point in the week where exhaustion over takes me and I need a justification for why I put myself thru what I do? Am I benefiting from it? What is the point?