Background. The role of stress in the onset of chronic fatigue syndrome is unclear. Our objectives in this study were first, to determine the relation between the onset of chronic fatigue syndrome and stressful life events and difficulties. Secondly, we examined the role of a particular type of problem, dilemmas, in the onset of chronic fatigue syndrome.

Method. We used a case–control design with 64 consecutive referrals from an Infectious Diseases/Liaison Psychiatry Fatigue clinic and 64 age- and sex-matched controls from a general practice population control group in Leeds. We had two main outcome measures; the odds ratios of the risk of developing chronic fatigue syndrome after experiencing a severe life event, severe difficulties or both in the year and 3 months preceding onset; and the proportion of subjects in each group who experienced a dilemma prior to onset.

Results. Patients with chronic fatigue syndrome were more likely to experience severe events and difficulties in the 3 months (OR=9, 95% CI 3·2 to 25·1) and year (OR=4·3, 95% CI 1·8 to 10·2) prior to onset of their illness than population controls. In the 3 months prior to onset 19 of the 64 patients (30%) experienced a dilemma compared to none of the controls.

Conclusions. Chronic fatigue syndrome is associated with stressful events and difficulties prior to onset. Those events and difficulties characterized as being dilemmas seem to be particularly important.