Introduction

Stressful life events have been linked to a range of immune-related disorders, including autoimmune diseases, infectious diseases and cancer. Some of the most compelling evidence for stress and disease associations stems from viral challenge studies, in which volunteers are exposed to a cold or influenza virus and then monitored in quarantine for the development of infection and illness. These studies find that individuals with more life stress, as measured by a higher number of recent stressful life events, higher perceived stress and more negative affect are more likely to develop colds than individuals with lower levels of stress (Cohen et al., 1991), and that stressful events lasting a month or more are better predictors of developing colds than those of a briefer duration (Cohen et al., 1998). In addition, individuals who are more sociable and have a diverse social network are less likely to develop a cold (Cohen et al., 2003; Cohen et al., 1997), possibly because such factors may be able to decrease the frequency of stressful life events or buffer deleterious effects of stress.

In addition to disease outcomes, stressful life events may also delay the healing of wounds. Recent studies have shown that long-term care givers who were caring for a severely ill family member experienced greater emotional distress and took nine days longer to heal a dermal punch biopsy wound than age- and income-matched controls (Kiecolt-Glaser et al., 1995).