Depression is something a student should be self-aware of when applying to colleges, but IMO, not something used to explain away one’s underperformance in a college application.
I also don’t think college rankings are highly correlated with potential stress. Harvey Mudd, for example, is ranked #28 among LACs on USNWR (I had to look it up because I don’t pay attention to rankings), but it’s by far the most stressful among all LACs for a typical student. How much stress a student may feel depends on how poorly s/he fits with the college (and its program) academically.