The vagus nerve acts as the main two-way communication superhighway between your brain and your internal organs, controlling your body’s involuntary “rest and digest” system.
The vagus nerve, cranial nerve X, is the longest cranial nerve in your body. It starts in your brainstem and travels down through your neck, chest, and abdomen, branching out to your heart, lungs, and gut. It handles information in two directions using nerve fibers:
Afferent fibers (approximately 80%) send status reports from your organs to your brain (sensory fibers). They tell your brain if your stomach is full, how fast your heart is beating, and whether there is inflammation or pain. Efferent fibers (approximately 20%) send commands from your brain to your organs to trigger physical actions (motor fibers).
Which functions does the vagus nerve control?
Heart rate. It acts as a biological brake. It sends signals to slow down your heart rate when you are calm or recovering from stress.
Digestion. It triggers the muscles in your stomach and intestines to move food along and tells your digestive glands to release juices.
Inflammation control. It helps turn off excessive immune responses, acting as an anti-inflammatory pathway.
Reflexes. It controls involuntary actions like swallowing, speaking, coughing, and gagging.
What is low vagal tone?
Low vagal tone means the vagus nerve is working less effectively, which reduces your body’s ability to switch into a relaxed, rest-and-digest state after stress. While vagal tone cannot be measured directly, doctors and fitness trackers estimate it using heart rate variability.
Low vagal tone is not a standalone disease, but it is linked to several health patterns, including digestive issues (bloating, slow motility, or irritable bowel syndrome), mental health issues (higher rates of anxiety, depression, and chronic stress), cardiovascular impact (reduced heart rate variability and a harder time recovering after physical or emotional stress), and systemic inflammation (ongoing, low-grade inflammation because the nerve fails to properly regulate immune responses).
What are benefits of enhanced vagal tone?
Enhanced vagal tone improves physical and mental health by optimizing parasympathetic nervous system activity, which helps the body recover from stress and maintain internal balance.
Heart health. Lowers resting heart rate and increases heart rate variability (HRV), leading to more efficient cardiovascular function and faster physical recovery after exercise.
Stress and emotion regulation. Sharpens executive function under pressure, reduces anxiety, and helps the body switch smoothly out of the “fight-or-flight” response.
Reduced inflammation. Activates descending pathways that lower the production of harmful pro-inflammatory cytokines, which may help manage chronic inflammatory conditions.
Digestion. Supports normal gastrointestinal motility and secretions via the “rest-and-digest” functions.
Dolphin Vagal Nerve Stimulation
The Dolphin Neurostim is a microcurrent device that has been proven in studies to reduce stress, balance the nervous system, and increase parasympathetic function of healing, recovery, immunity, rest, digest and repair. The Dolphin is a passive treatment which applies direct low-frequency microcurrent stimulation to the ear and throughout the entire vagus nerve track providing deep vagal tone enhancement — it “mimics” the human nervous system and promotes electrical rebalance of cells. The government of Canada has approved the Dolphin device for use in the treatment of acute and long COVID because of its ability to improve the body’s natural ability to regulate the inflammatory response. Dolphin is the only published, evidenced-based vagal stim therapy scientifically proven to improve the vagus nerve.
Noninvasive vagal stimulation (NVS) is the application of tiny microcurrents to the ear, targeting the auricular branch of the vagus nerve, which is considered the “brakes” of the body. Vagus nerve activation is proven in science to reduce pro-inflammatory cytokines, to stimulate immunity, and to improve respiratory dysfunction. NVS is reported to alleviate many conditions, including epilepsy, depression, and pain and to assist in stroke rehabilitation. NVS is also widely reported in science to increase vagal tone and improve respiratory-pulmonary functioning, and is applied to treat long COVID recovery.
Individuals with heart conditions should avoid this treatment. The current can interfere with the function of pacemakers, cochlear implants, or other electronic devices. The device should not be used over metal plates, pins, or dental hardware, as these can conduct the current and cause damage. The electrical current could trigger seizures. The stimulation can affect cells, so it is advised against for those with active cancer. Safety in pregnancy has not been established.
Research
Aranberri, R. (2024). Transcutaneous auricular vagus nerve stimulation to improve emotional state. Biomedicines.
Breit, S., Kupferberg, A., Rogler, G., et al. (2018). Vagus nerve as modulator of the brain-gut axis in psychiatric and inflammatory disorders. Frontiers in Psychiatry.
De Couck, M., Caers, R., Spiegel, D., et al. (2018). The role of the vagus nerve in cancer prognosis: A systematic and a comprehensive review. Journal of Oncology.
de Lartigue, G. (2016). Role of the vagus nerve in the development and treatment of diet‐induced obesity. Journal of Physiology.
Lamb, D., Porges, E., Lewis, G., et al. (2017). Non-invasive vagal nerve stimulation effects on hyperarousal and autonomic state in patients with posttraumatic stress disorder and history of mild traumatic brain injury: Preliminary evidence. Frontiers in Medicine.
Loper, H., Leinen, M., Bassoff, L., et al. (2021). Both high fat and high carbohydrate diets impair vagus nerve signaling of satiety. Scientific Reports.
Pavlov, V., & Tracey, K. (2012). The vagus nerve and the inflammatory reflex—linking immunity and metabolism. Nature reviews. Endocrinology.
Additional Information
5 ways to stimulate your vagus nerve | Cleveland Clinic
Is this 5-minute microcurrent facial better than botox? | Healthline
The key to depression, obesity, alcoholism — and more? Why the vagus nerve is so exciting to scientists | The Guardian
Microcurrent electrical neuromuscular stimulation | Physiopedia
Microcurrent point stimulation: A new hope | USA Today
Vagus nerve stimulation | Cleveland Clinic
Vagus nerve stimulation | Mayo Clinic
What are the benefits of cold and hot showers? | Medical News Today