Abnormal functional connectivity of the anterior cingulate cortex subregions mediates the association between anhedonia and sleep quality in major depressive disorder

•Patients with MDD exhibited aberrant rsFC of the ACC subregions, indicating the abnormal connectivity in the DMN intra- and inter-subsystems.•The severity of consummatory anhedonia and sleep quality were correlated with the strength of some altered rsFC in MDD.•Aberrant rsFC between the DMN and sensorimotor network mediated the association between sleep quality and consummatory anhedonia in MDD patients.•These findings emphasized that changes in the ACC play an important role in the pathophysiology of the MDD.