[slitaz]

I think it is so straightforward. Chronic stress is bad for the health in general due to the effects of cortisol to the body.

Some people may deal with stress (as Sapolsky describes), so the effects of cortisol are not pronounced.

Those that cannot deal with the stressors, are those most affected and they are those that will admit they are stressed.

It is an issue of people tending to admit something, in a qualitative study.