An Investigation of Fatigue-Related Interpretation Bias and Fatigue in Insomnia

Fatigue is a distressing symptom of insomnia and cognitive theory suggests that people with insomnia selectively scan for, and interpret innocuous experiences throughout the day (e.g., a momentary lapse in memory) as evidence of fatigue (Harvey, 2002). The tendency to interpret experiences as evidence of fatigue (i.e fatigue-related interpretation bias) may contribute to increased impairment in insomnia (Harvey, 2002). There are two studies in this thesis. Study 1 generated parallel forms of a fatigue-related interpretation bias measure using rational and empirical methods. Study 2 investigated whether fatigue related interpretation bias increased on the equivalent forms from Study 1, following a fatigue induction. Fatigue-related interpretation bias scores were related to insomnia severity as expected, but fatigue-related interpretation bias did not increase following the fatigue induction. Analyses suggested that the parallel forms were not equivalent in the new sample and more psychometric work is needed. Implications and suggestions for future research are discussed.