A randomized controlled trial of mild hyperbaric oxygen therapy on cognitive performance and sleep quality in healthy young adults at high altitude: Exploratory functional near-infrared spectroscopy study

Background Enhancing oxygen-carrying capacity has been suggested as a potential therapeutic strategy for alleviating sleep quality and cognitive performance at high-altitude. Methods 60 healthy young male participants who had resided at 4300 m for at least six months, were enrolled and randomly assigned at a 1:1 ratio to either a mild hyperbaric oxygen (mHBOT) group or a control group for a 5-day intervention. The primary outcomes included insomnia severity, assessed using the Pittsburgh Sleep Quality Index (PSQI), and brain function, evaluated via functional near-infrared spectroscopy (fNIRS) during 2-back and working memory (WM) task. Results Following the intervention, the mHBOT group showed a significantly greater reduction in PSQI scores compared to the control group (3.17 ± 2.69 vs. 4.43 ± 3.39; adjusted mean difference [aMD] = −1.08, 95% CI: −1.76 to −0.46, p = 0.003). In terms of cognitive performance, the mHBOT group achieved a significantly higher accuracy rate on the WM task than the control group. Furthermore, fNIRS data indicated a significant decrease in oxygenated hemoglobin levels in the superior temporal gyrus (STG; channels 18–22) during WM performance after mHBOT compared to baseline (FDR-corrected p < 0.05), suggesting altered activation patterns and reduced metabolic demand in this region. Analysis of cerebral functional connectivity also revealed enhanced network integration and modified activation profiles following mHBOT treatment, may indicate improved neurocognitive efficiency. Conclusion Findings indicate that mHBOT may be a promising intervention for enhancing both sleep quality and cognitive performance in healthy young adults at high altitude. © 2026 The Authors.