The BBC has an interesting piece here on the problem of student ghost cities in the United Kingdom. The problem is that many parts of cities become absolutely deserted when students leave (and overwhelmed during the academic year).
Why is this? Unlike the United States, the overwhelming number of undergraduate students in the UK live off-campus in private accommodation. They live --- at least in one case I know of --- up to 12 people in one home. When the academic year begins, parking becomes impossible as out of nowhere several cars per home emerge overnight. Then people and cars --- and the weekend parties --- disappear for the summer only to return in September.
I am not sure that new zoning laws would be the best way forward. For one thing, there will be strong opposition from land owners who rent to students --- and they remain the primary players until a true alternative emerges. For another, and as much as I sympathize with those who worry about inevitable drops in property values when student homes move in, I am libertarian on where (and where not) student homes may be situated. It is hardly surprising that these "ghost cities" are normally areas near campus. (Thus, the solution would be to move the campus in order to move the private student accommodation.)
A better solution might be to move more towards the US-model (if it can be called that). It is typical to find ample accommodation on campus for students with kitchens, cafeteria, and so on. This does not deny students the opportunity to live in private accommodation, but the latter may be less attractive if cheaper accommodation/meals were available on campus. There might be better security for students, as fewer might live off campus (and student homes are prime targets for thieves as they may expect several televisions, stereos, laptops, cd's, and the like they can easily sell off). In addition, it would help eliminate the "problem" of "ghost cities" (indeed, if it is a problem) as most students would live on campus.
UPDATE: An excellent guide for students on private accommodation can be found here.