Microbaric oxygen therapy modulates EEG microstates and spectral power in patients with chronic insomnia disorder

Abstract Background Chronic Insomnia Disorder (CID) is a prevalent condition. This study examines microbaric oxygen therapy (MOT) as a non-pharmacological intervention for CID patients, utilizing EEG to investigate its effects on neural mechanisms and provide novel electrophysiological evidence. Method In this longitudinal non-randomized study, CID patients from a tertiary hospital were allocated to oxygen therapy (OT) or non-oxygen therapy (NOT) groups. The OT group received daily 45-minute MOT sessions combined with pharmacotherapy, while the NOT group received pharmacotherapy alone. Assessments at baseline, week 1, and week 5 evaluated sleep quality, mood, cognition, and high-density EEG parameters including microstates, event-related potentials, and time-frequency features. Statistical analyses employed t-tests/Mann-Whitney U, chi-square/Fisher’s tests, and repeated-measures ANOVA with sphericity correction. Results The study included 40 OT and 38 NOT participants. Eye-closed resting EEG microstate analysis indicated that OT led to shorter microstate D duration, increased microstate C occurrence and contribution, decreased microstate D contribution, and altered transition probabilities. Quantitative analysis of the task-related time-frequency data showed that enhanced theta (4–8 Hz) and alpha (8–13 Hz) power during inhibition and a posterior beta (13–20 Hz) shift, suggesting improved conflict monitoring and resource allocation. However, conventional ERP analysis did not reveal any significant between-group differences. Conclusions MOT induces clinically meaningful electrophysiological changes in CID patients, as evidenced by reduced resting-state microstate D (linked to hyper-arousal) and enhanced task-related theta/alpha power (reflecting improved conflict monitoring). This pattern suggests a shift from maladaptive hyper-vigilance toward more efficient cognitive control. These findings provide novel electrophysiological evidence for the neural basis of insomnia-related cognitive impairment and support its further development as a complementary therapeutic strategy. Trial registration ClinicalTrials. ChiCTR2300072452. Registered on June 14, 2023.