Task-induced hyperfunction of the left dorsolateral prefrontal cortex in patients with primary insomnia: a near-infrared spectroscopy study during a verbal fluency task

Introduction: In this study, we aimed to use functional near-infrared spectroscopy (fNIRS) to investigate the differences in the functional brain activation of patients with primary insomnia (PI) and that of good sleepers (GSs) without other comorbidities or structural abnormalities during a verbal fluency task (VFT). Methods: Thirty PI participants and 30 GSs completed a clinical questionnaire and performed VFT during an fNIRS scan. A two-sample t-test was performed to compare brain activation on a cognitive test between patients with PI and GSs. Results: We observed higher brain activation in the left dorsolateral prefrontal cortex in the insomnia group during VFT compared to GSs (p < 0.05). Discussion: Our findings may contribute to an understanding of the neural mechanisms in patients with PI.