A team of scientists from the Institutes of Brain Science at Fudan University has identified a nose-to-brain circuit that links the frequency of nasal airflow to anxiety regulation in mice. The researchers found that slow, rhythmic nasal breathing dampens anxiety by activating a specific neural pathway, while rapid breathing has the opposite effect. The findings, published in the Proceedings of the National Academy of Sciences, also showed that a daily regimen of simulated slow breathing can produce lasting relief from anxiety-like symptoms.
To map the effect, the researchers exposed mice to distinct breathing frequencies—two breaths per second as slow, four per second as moderate, and seven per second as fast—and used optogenetics to selectively drive the olfactory sensory neurons with light, thereby controlling firing rates without altering actual breathing. The mice were then tested in behavioural arenas, including the Elevated Plus Maze and the Open Field Test, where spending more time in open areas indicates lower anxiety.
Slow nasal stimulation boosted high-gamma waves in the perirhinal cortex, while fast stimulation reduced them; higher high-gamma activity correlated with lower anxiety in the mice. The electrical signals travel from the olfactory sensory neurons in the nose to mitral cells in the olfactory bulb, then to a type of neuron in the perirhinal cortex known as parvalbumin-positive interneurons, and finally to the basolateral amygdala, a key region in fear and anxiety processing.
“We wanted to settle this causally,” Wu continued. “Our answer: the airflow itself is the signal. Its frequency alone, independent of breathing effort or conscious control, shifts anxiety up or down.”
“How you breathe through your nose is not just a reflection of your emotional state; it is an input your brain actively reads,” Wu said. “Slow nasal breathing engages a specific brain circuit that lowers anxiety, while fast nasal breathing pushes the same circuit in the opposite direction. This gives scientific grounding to breathing practices, with a caution: rapid breathing during stress is not just a symptom of anxiety, it may actively feed it.”
“The behavioural effects in mice were robust and reproducible, and a brief daily regimen of low-frequency nasal airflow produced lasting reductions in anxiety-like behaviours,” Wu said. “But this is a mouse study. The main value is establishing the principle and the mechanism: frequency-tuned nasal input is a legitimate handle on the anxiety system. Translation to humans will require clinical testing.”
“This is a mouse study, so human benefits remain to be demonstrated,” Wu cautioned. “The effect depends on nasal airflow specifically, so mouth breathing would not engage this circuit; the advice should really be ‘breathe slowly through your nose.’ And this is a promising research direction in clinical anxiety.”
“One broader point: the nose may be an underappreciated gateway into the brain,” Wu concluded. “Because nasal input reaches limbic circuits, bypassing the thalamus, the nasal route offers a noninvasive and accessible window for regulating brain states. We hope this work encourages more attention to this direction.”
The study was authored by Xinsong Guo, Mengyan Liu, Qingcheng Xiong, Howai Ngai, Mingdong He, Xinying Li, Yingwei Zheng, Fuqiang Xu, Minghong Ma, and Ruiqi Wu.
If translated to humans, the researchers say the mechanism could offer a noninvasive means of modulating anxiety, though the present work remains a mouse study. The team noted that the enhanced anxiety in the animals following fast nasal input and the calming effect of slow nasal input were observed without other cues, raising the possibility of targeted nasal stimulation as a potential therapeutic approach pending clinical testing.
Previously, research noted that anxiety-inducing environments can prompt faster breathing and corresponding shifts in brain activity, a finding that aligns with the current work by illustrating a link between nasal airflow patterns and neural states. The researchers caution that human benefits require careful clinical validation and stress that mouth breathing would not engage the same circuit.
Looking ahead, the investigators outlined three directions: testing whether the same principles hold in humans, exploring whether the nose-brain axis is disrupted in disorders involving olfactory abnormalities, and studying how nasal stimulation might be used in a practical, protocol-based manner. “The nose may be an underappreciated gateway into the brain,” Wu concluded, emphasising the potential for noninvasive approaches to regulate emotional states.
