Abstract
BACKGROUND: Previous findings have demonstrated that habenula (Hb) is a key hub for sleep regulation and emotion processing. However, its role in chronic insomnia disorder (CID) remains understudied. This study aimed to investigate the structural characteristics of the Hb and its functional connectivity (FC) with large-scale brain networks in CID patients. METHODS: A total of 42 CID patients and 31 age-, gender-, and education-matched healthy controls (HC) completed clinical questionnaires, structural magnetic resonance imaging (sMRI) and resting-state fMRI (rs-fMRI). RESULTS: No significant group differences were observed in the relative volumes or the laterality index between CID patients and HC. However, voxel-wise FC analysis showed increased FC between the left Hb and the right inferior frontal gyrus, right middle frontal gyrus, and left angular gyrus in CID patients, alongside decreased FC between the left Hb and left inferior frontal gyrus, left precentral gyrus, and right caudate nucleus. The right Hb exhibited decreased FC with the right middle cingulate cortex, supramarginal gyrus and postcentral gyrus. Region-of-interest (ROI)-wise analysis further demonstrated that the left Hb had significantly decreased connectivity with the posterior/anterior somatomotor networks (SM-d, SM-v) and posterior dorsal attention network (DAN-p) in CID patients. CONCLUSION: Our findings indicate that CID is characterized by asymmetric FC abnormalities of the bilateral Hb, particularly impaired connectivity between the left Hb and SM and DAN networks, without structural changes. These aberrations provide novel neuroimaging insights into the pathophysiology of CID and highlight the left Hb as a potential target for targeted interventions.