Neural mechanism of Shugan Jieyu combined with zolpidem in insomnia disorder with depressive symptoms: evidence from event-related potentials in Go/No-Go and psychomotor vigilance task

The study aims to investigate the combination’s effects of Shugan Jieyu and zolpidem on executive functions and sustained vigilance in patients with Insomnia Disorder with Depressive Symptoms (IDDS). In this randomized controlled trial, IDDS patients were allocated to receive either zolpidem plus Shugan Jieyu (ZS group) or zolpidem plus placebo (ZP group) for 8 weeks. Go/No-Go and Psychomotor Vigilance Task (PVT), coupled with Electroencephalography (EEG), were used to assess behavioral performance and underlying neurophysiological activity at baseline, fourth week, and eighth week after treatment. While no significant between-group differences were found in the behavioral measures of the Go/No-Go task, an exploratory ERP analysis revealed that the ZS group showed a more negative Go N2 amplitude at the fourth week compared to the ZP group, F(1,56) = 5.161, p = 0.027, suggesting a potential early enhancement of conflict monitoring. In the PVT, the ZS group demonstrated significantly faster mean reaction times at the eighth week (F(1,57) = 4.143, p = 0.046). For attention lapses, no significant Group × Time interaction was found (F(1.834,104.543) = 0.515, p = 0.583); however, an exploratory analysis suggested fewer lapses in the ZS group at Week 8 (F(1,57) = 4.301, p = 0.043). For ERP, a significant Group × Time interaction was found for the N1 amplitude (F(1.829, 104.242) = 3.314, p = 0.044), indicating that N1 negativity increased over time in the ZP group but remained stable in the ZS group, suggesting a potential stabilization of early sensory processing. The combination of Shugan Jieyu and zolpidem was associated with cognitive function improvements in patients with IDDS, including enhanced neural conflict monitoring and improved sustained vigilance. These findings suggest that this combination therapy may offer cognitive benefits beyond sleep improvement in IDDS. ClinicalTrials.gov (NCT05764798), registered on February 19, 2023.