I just read this article (from 2004). Its pretty good. Edit: Both authors have spent their lives studying the link between stress and disease, so may be biased in favour of positive findings. Keep this in mind as you read. Psychological stress and the human immune system: a meta-analytic study of 30 years of inquiry. Its a metanalysis. Tries to gather all studies that have looked at the same thing and calculate average effects across all like studies. Over the short term (e.g. things like exam stress, public speaking), stress enhances several aspects of immune function, especially the natural immune response (NK cells and stuff). But for stress over the long term, results were pretty patchy. First, the positive outcomes: * Death of a spouse was the only single event that elicited any significant consistent change in immune response, it was associated with a decline in natural immune response (e.g., reduced NK cell function). * Chronic stressors, which included dementia caregiving, living with a handicap, and unemployment, also resulted in changes to a number of markers of immunity, including cytokine production, NK cells, and antibodies to herpes viruses. Now the negative: * Stressful event sequences, taken together (e.g. death of a spouse, experiencing a natural disaster, possible cancer diagnosis), didn't elicit any consistent pattern of immune change across studies. * Distant stressors (things like childhood trauma and war experiences many years back) had no consistent reliable effect on immune parameters. * There is no relationship between people's self-rated stress levels and any immune parameters The authors suggest that some of the effects of chronic stressors may actually be indirect, and due to things like loss of sleep, changes in smoking habits, etc.