<p>Sleep critically influences socio-emotional functioning during interpersonal interactions; however, the relationship between poor sleep quality and susceptibility to social exclusion remains unclear. This study aimed to investigate this relationship and its underlying neural mechanisms. A total of 147 healthy sleepers (HS) and 105 individuals with poor sleep quality (PS) completed a social exclusion imagery task, followed by resting-state functional magnetic resonance imaging (fMRI). Negative feelings and reaction times during the task, as well as seed-based functional connectivity (FC) of the left ventral anterior cingulate cortex (vACC) and left inferior frontal gyrus (IFG), were compared between groups. Associations between FC showing group differences and behavioral measures were further examined. After controlling for depressive and anxiety symptoms, the PS group exhibited stronger negative feelings during the task and longer reaction times in neutral conditions. Seed-based FC analysis revealed increased connectivity between the left IFG and left temporal lobe (TL), alongside decreased connectivity between the left IFG and right precentral gyrus (PG) in the PS compared to the HS group. Moreover, FC between the IFG and PG was negatively correlated with negative affect in HS but not in PS. Poor sleep quality is associated with heightened susceptibility to social exclusion, potentially linked to altered functional connectivity between the IFG and PG. These findings underscore the protective role of healthy sleep in social functioning and suggest neural targets for interventions aimed at mitigating social impairments in individuals with poor sleep.</p>