How sleep disturbances affect internet gaming disorder: The mediating effect of hippocampal functional connectivity.

<bold>Background: </bold>Studies have revealed that sleep disturbances lead to an increased risk of Internet gaming disorder (IGD). However, the neural underpinnings of this feature remain unknown. Exploring this issue would be valuable in understanding the relationship between sleep and psychiatric disorders.<bold>Methods: </bold>Given the impact of sleep on reward circuitry, we examined nucleus accumbens (NAcc) and hippocampal resting-state functional connectivity (rsFC) differences between 41 IGD subjects and 59 healthy controls. Significant connections were determined and used to examine correlations with clinical variables. Finally, we explored the relationship between neuroimaging findings, IGD severity and sleep disturbances through a mediation model.<bold>Results: </bold>We observed the connection deviation between the hippocampus and a wide range of cerebral cortexes in IGD subjects, including the prefrontal, parietal and temporal lobes. More importantly, the right posterior hippocampus (pHIP)-left caudate rsFC was positively correlated with both the Pittsburgh Sleep Quality Index (PSQI) and Internet Addiction Test scores and mediated the relationship between the two. For the NAcc, a difference between groups was only observed in the rsFC between the shell partition of the NAcc and the inferior orbitofrontal cortex, but this connectivity was not related to the PSQI score.<bold>Conclusions: </bold>IGD subjects showed a wide range of abnormal connections in the hippocampus, involving memory, reward motivation, and cognitive control. Here we emphasized the potential of the hippocampus in studying sleep disturbances in IGD, especially the coupling between the pHIP and caudate nucleus, which could provide novel insight into how sleep interacts with motivational systems in IGD subjects. [ABSTRACT FROM AUTHOR]