The relation between life changes, stress, and illness

I have often wondered about my personal experience and the anecdotal evidence that when you get stressed you seem more likely to get a cold or the flu. I finally found some research literature on the subject.
A helpful review is
Modern Approaches to Conceptualizing and Measuring Human Life Stress
Scott M. Monroe

A seminal paper from 50 years ago
The social readjustment rating scale 
TH Holmes, RH Rahe

The authors developed a quiz to estimate how your recent life circumstances and changes may be producing different levels of stress. They then correlated the stressful life circumstances to recent illness of the subjects.

It is worth occasionally doing the quiz. Here is one version.
Aside: One interesting aspect is that positive changes can create stress (e.g. starting a new job, getting married, having a baby, ...).

However, as discussed in detail by Monroe in his review all of this is more complicated than we might like. Measures of stress are subjective, subtle, personal, and hard to agree upon. For example, do you define the level of stress largely in terms of the environment or in terms of the response of the individual to the environment?
This is hardly surprising given that the subject is at the interface of medicine, psychology, and sociology.