Apparently college students in the US, at every level, are studying for significantly fewer hours (14 per week, down from 24 in 1961) than they used to. The Atlantic Wire has collected some ideas about why this might be.
My favourite is described as "professor apathy" but actually refers to "the growing power of students and professors’ unwillingness to challenge them." The growing power of students is not the result of professor apathy, of course, but of the tendency of administrators to treat colleges as markets and students as customers. If your continued employment depends on keeping your customers happy--and this by design on your employers' part--then it is not apathy that encourages you not to make those customers work too hard. Elective courses that attract few students are not likely to be offered again. Not because of professor apathy but because of administrative policy. Adjunct professors whose courses attract few students are unlikely to be re-hired, for the same reason. Departments that graduate few majors are liable to be shut down.
Two other things might be worth saying. Only a small drop in hours of studying has occurred since 1981 (2.8 hours per week), which might be explained by improved efficiency in doing research thanks to the internet. So the biggest drop occurred in the 1960s and 70s. Could this be because a change occurred during those decades in what people took college to be about? A higher percentage of the population started going to college then, and it is an era associated with both political protest and sex-and-drugs. Political protest seems to have died down, but partying appears to be bigger than ever. Did it always? Or is this a result of intellectuals making up a smaller percentage of the student population? (I don't mean this to be read as a dichotomy.) I don't know. And, since at least some partying must always have gone on, it's probably more important that so many students have to work to pay their way through college. That must reduce the time they spend studying.
Finally, it isn't simply that more people are going to college, because the drop is supposed to have happened across the board, not only at colleges that teach primarily the kind of student who previously would not gave gone to college at all. But if people used to think of college as a place to read books and now think of it as Animal House (a very big 'if') then I would expect this to affect Harvard as well as South West Central State, at least to some extent. Harvard probably also admits more students now who are not rich, and these people presumably often work part-time too.
Mostly I'm struck by the way bad administration is presented as "professor apathy" (because those lazy professors should have resisted the innocent mistakes of the administrators, even if it meant risking being fired) and by lots of head-scratching about something that seems entirely predictable given the half-baked, pseudo-economic thinking-in-slogans that lies behind this kind of administration. If you put pressure on schools to have high retention rates, then they will not flunk as many students as before. This means fewer Fs, which means grade inflation. If you put pressure on professors to get good evaluations from their students and to attract students to take their courses, you will get more grade inflation and less demanding courses. If you push for everyone to go to college, college students will be more like everyone else. And normal people don't study for many hours a week.
For more discussion see here and here.