Do burnout and insomnia predict each other's levels of change over time independently of the job demand control-support (JDC-S) model?

In past research, the job demand control-support (JDC-S) model was found to predict both burnout and insomnia. Recent evidence suggests that burnout and insomnia are reciprocally associated with each other across time. The objective of this study was to test whether there is an additive effect of burnout on subsequent changes in insomnia over and above the effect of the JDC-S model, and the reverse causation hypothesis expecting insomnia to have an additive effect on subsequent levels of burnout. Subjects were 3,235 apparently healthy employed adults who completed questionnaires during a periodic health examination at two points of time, Time I (T1) and Time 2 (T2), about 18 months apart. Depressive symptomatology, body mass index, age, gender, follow-up duration and T1 levels of the criterion were controlled. As hypothesized, the results indicate that T1 insomnia predicts the T1-T2 change in burnout over and above the influence of the T1 JDC-S model, and further that T1 burnout predicts the T1-T2 change in insomnia over and above the influence of the T1 JDC-S model. The results suggest that burnout and insomnia may adversely affect one another even in workers with low job strain. Several possible mechanisms of the link between JDC-S model, burnout and insomnia are suggested. Copyright (C) 2009 John Wiley & Sons, Ltd.