The impact of negative mood state on sleep-related attentional bias in insomnia

Sleep-related attentional bias is thought to play a role in the maintenance of insomnia. However, this concept has been questioned by several studies that did not show the presence of sleep-related attentional bias in clinical insomnia or poor sleepers. Our goal in the present study was to test whether the mood state of individuals with insomnia affects the presence of sleep-related attentional bias. To this end, 31 individuals with insomnia and 34 good sleepers were randomly assigned to a negative mood-inducing condition or a control condition. They then completed a visual probe task with three types of pictorial stimuli (general threat, sleep-related negative pictures and sleep-related positive pictures). Vigilance, maintenance and the overall bias indexes were calculated based on the reaction time. We found individuals with insomnia only showed a greater overall bias compared with good sleepers following a negative mood induction, regardless of the pictures presented. In addition, we found that a negative mood state was significantly correlated with the overall attentional bias in good sleepers but not in individuals with insomnia. These findings suggest that sleep-related attentional bias in insomnia can be modulated by mood state. This effect may reflect the dysregulation of top-down attentional control in individuals with insomnia.