Hydrogen Breathing Changes Brain Activity and Heart Function
- Authors
- Masamichi Moriya, Katsunori Oyama, Yutaka Den, Yukio Yamada, Kaoru Sakatani
- Journal
- Nature Scientific Reports
- Year
- 2026
- DOI
- 10.1038/s41598-026-36599-8
- Study Type
- Human
- Outcome
- Positive
- Peer Reviewed
- Yes
- Country
- Japan
- Health Condition
- Cognitive Function
- Body System
- Nervous System
TL;DR
Hydrogen inhalation temporarily altered brain oxygenation and autonomic nervous system activity, indicating effects on neurovascular and cardiovascular regulation.
Key Finding
Hydrogen inhalation produced temporary increases in right-side brain oxygenation in the prefrontal cortex paired with sympathetic nervous system activation during inhalation, followed by parasympathetic recovery afterward.
Summary
Researchers had healthy adults inhale pure hydrogen gas for 30 minutes and measured changes in brain blood oxygen levels and heart rate patterns. They found that hydrogen inhalation temporarily increased oxygen levels on the right side of the brain's prefrontal cortex (the area involved in decision-making) and caused shifts in the nervous system's activity—first activating the sympathetic nervous system (fight-or-flight response) during inhalation, then activating the parasympathetic nervous system (rest-and-digest response) afterward.
Practical Takeaway
This small study suggests hydrogen gas inhalation may temporarily affect brain oxygenation and nervous system balance in healthy people, but the effects were transient (short-lived) and the study did not measure any actual health outcomes. Much larger and longer studies would be needed to determine whether these changes have any meaningful benefit for cognitive or cardiovascular health.
Abstract
Molecular hydrogen (H2) has selective antioxidant and anti-inflammatory properties, yet its immediate effects on human cerebral oxygenation and autonomic function remain unclear. In this study, we evaluated acute central and autonomic responses to a single 30-minute session of hydrogen inhalation in healthy adults, using 99.9% hydrogen delivered via nasal cannula at a fixed flow rate of 300 mL/min. Cerebral oxygenation was assessed using time-domain near-infrared spectroscopy (TD-NIRS) to quantify the concentrations of oxyhemoglobin (oxy-Hb) and deoxyhemoglobin (deoxy-Hb) in the bilateral prefrontal cortex (PFC), and to calculate interhemispheric asymmetry indices before hydrogen inhalation, immediately after the end of inhalation, and at 30 and 90 min thereafter. Autonomic activity was assessed via continuous electrocardiography (ECG) to derive heart rate, R-R interval, and frequency-domain heart rate variability metrics (low-frequency (LF), high-frequency (HF) and LF/HF ratio). Hydrogen inhalation elicited robust, transient increases in the right-PFC asymmetry of the oxy-Hb concentration. Concurrently, the LF/HF ratio increased during inhalation, indicating sympathetic activation, followed by decreases in the heart rate after inhalation, consistent with parasympathetic recovery. These parallel cerebral and autonomic responses suggest a coordinated neurovascular-autonomic coupling in response to hydrogen inhalation. Our findings show that acute hydrogen inhalation transiently modulates PFC oxygenation lateralization and autonomic tone, suggesting potential relevance to cognitive and cardiovascular regulation.