HD-tDCS over prefrontal cortex alleviates the inhibitory control and sleep problems of insomnia with objective short sleep duration

Background: Insomnia disorder with objective short sleep duration (ISSD) is a severe phenotype associated with significant health risks including hypertension, diabetes, and cognitive impairment. It has been found that sleep problems in ISSD can be alleviated by improving inhibitory control (IC) ability. Therefore, there is a need to develop more effective interventions targeting inhibitory control to relief the symptom in ISSD. Objective: This study aimed to investigate whether high-definition transcranial direct current stimulation (HD-tDCS) targeting the right dorsolateral prefrontal cortex (dlPFC) could improve inhibitory control and sleep quality in ISSD. Methods: In a randomized, single-blind, sham-controlled trial, 50 ISSD were assigned to real (n = 25) or sham (n = 25) HD-tDCS groups (2 mA, 25 min/day for 7 days). Forty-one participants completed the study (real: 21, sham: 20). Primary outcomes were inhibitory control (accuracy of NoGO trial in Go/NoGo task, NoGo-ACC) and subjective sleep quality (Pittsburgh Sleep Quality Index; PSQI; Insomnia Severity Index, ISI). Secondary outcomes included objective sleep measures (total sleep time, sleep latency) collected via forehead EEG device. Results: After the intervention, participants who received HD-tDCS had significantly better response inhibition (NoGo-ACC) and sleep quality (ISI, PSQI, sleep latency subdimension of PSQI, and daytime functioning subdimension of PSQI) than the sham group. Conclusions: These findings establish right dlPFC-targeted HD-tDCS as a potentially safe and effective neuromodulatory approach for ISSD, though optimized protocols may be required for full clinical remission. Future studies should investigate combined interventions and include neurochemical assessments to elucidate underlying mechanisms. Trial registration: The study was prospectively registered on September 29, 2024, in Chinese Clinical Trials registry (ChiCTR2400090393).