Sleep-related attentional bias in insomnia: A state-of-the-science review.

Prominent models of insomnia posit that sleep-related attentional bias plays an important role in the development and maintenance of insomnia. Here we conduct the first systematic review of the sleep-related attentional bias construct, indexed through reaction time-based experimental tasks. Literature search identified 13 studies that met pre-defined inclusion/exclusion criteria. Included studies involved between-group comparisons (poor sleepers versus controls), as well as sleep manipulations and correlational investigations with healthy sleepers. For studies involving comparisons between poor sleepers and healthy controls, effect size estimates were computed for task-relevant dependent variables. Six of the nine studies comparing poor sleepers and controls revealed statistically significant group differences in support of a differential sleep-related attentional bias (medium-to-large effect sizes), with flicker, dot-probe and Posner tasks being most sensitive to group effects. Due to the paucity of studies and variability in design and measurement, no conclusions could be reached regarding manipulation or induction of attentional bias in good sleepers. Results from the relatively small number of studies support the presence of sleep-related attentional bias in insomnia; however, its role in the development and/or maintenance of insomnia remains to be elucidated. We set out a research agenda aimed at advancing the understanding of sleep-related attention bias.