Reduced prefrontal activation during cognitive control under emotional interference in chronic insomnia disorder

This study investigated the altered neural activation underlying cognitive control under emotional and sleep-related interference conditions and its role in subjective sleep disturbance in patients with chronic insomnia disorder. In total, 48 patients with chronic insomnia disorder, and 48 age-, sex- and body mass index-matched controls were included in this study. They completed self-reported questionnaires to assess subjective sleep and emotional distress. A sleep diary was used to evaluate subjective sleep parameters. All participants performed the emotional Stroop task (three blocks each of negative emotional, sleep-related, and neutral words) during functional magnetic resonance imaging assessments. We compared brain activation during the emotional Stroop task between the two groups. We also analysed the correlations between altered neural activation and sleep variables. Less neural activation was detected in the right anterior prefrontal cortex of patients with chronic insomnia disorder than in controls when performing the emotional Stroop task with negative emotional words. The decrease in neural activation was negatively correlated with scores on Pittsburgh Sleep Quality Index, Insomnia Severity Index, and Dysfunctional Beliefs and Attitudes about Sleep Scale. In contrast, they were positively correlated with subjective total sleep time and sleep efficiency as reported in sleep diaries. A decrease in right anterior prefrontal cortex activity under the negative emotional words condition of the emotional Stroop task in patients with chronic insomnia disorder suggests a failure of top-down inhibition of negative emotional stimuli. This failure induces disinhibition of cognitive hyperarousal, manifested as rumination or intrusive worries, and potentially causing subjective sleep disturbances.