You’ve probably heard the phrase “trust your gut.” But what if your gut and your brain are barely talking to each other?

That’s exactly what happens when the vagus nerve isn’t working the way it should. And for a lot of people dealing with chronic symptoms that don’t have a clear explanation, this nerve is at the center of the problem.

At Nexus Neuro: Brain + Body in Carmel, Indiana, we take vagus nerve function seriously. Here’s what you need to know.

What Is the Vagus Nerve?

The vagus nerve is the longest cranial nerve in your body. It runs from your brainstem all the way down through your neck, chest, and abdomen. It connects your brain to your heart, lungs, digestive tract, liver, kidneys, and immune system.

Think of it as the main communication highway between your brain and your body.

It’s part of the parasympathetic nervous system, which is the “rest and digest” side of your autonomic nervous system. When your vagus nerve is working properly, it helps your body calm down after stress, regulate your heartbeat, move food through your digestive tract, manage inflammation, and process emotions.

When it’s not working properly, a lot can go wrong.

What Does the Vagus Nerve Actually Control?

The vagus nerve plays a role in more body functions than most people realize. Here are some of the key systems it regulates:

Heart rate. The vagus nerve slows your heart down after activity or stress. Poor vagal tone is linked to heart rate variability problems and can leave your heart rate elevated even when you’re at rest.

Digestion. Your gut relies on vagus nerve signals to move food, produce stomach acid, and coordinate the whole digestive process. When vagal signaling is off, you may notice bloating, nausea, slow digestion, or constipation.

Inflammation. The vagus nerve plays a direct role in regulating your body’s inflammatory response. Researchers call this the “inflammatory reflex.” Reduced vagal function has been linked to increased systemic inflammation.

Mood and anxiety. About 80% of the fibers in the vagus nerve travel from the body up to the brain, not the other way around. This means your gut is constantly sending signals to your brain. When those signals are disrupted, it can contribute to anxiety, depression, and mood instability.

Breathing. The vagus nerve helps regulate the muscles involved in breathing and coordinates the rhythm of respiration with your heart rate.

Immune function. Your vagus nerve communicates directly with your spleen and other immune tissues. It helps your body mount an appropriate immune response and then know when to stand down.

What Is Vagal Tone and Why Does It Matter?

You may hear the term “vagal tone” when reading about the vagus nerve. Vagal tone refers to how well your vagus nerve is functioning. High vagal tone is associated with better heart rate variability, calmer stress responses, healthier digestion, and lower inflammation. Low vagal tone is associated with the opposite.

Heart rate variability (HRV) is one of the most commonly used measurements of vagal tone. A higher HRV generally indicates a healthy, responsive nervous system. A lower HRV suggests the nervous system is under stress or not regulating itself well.

At Nexus Neuro, we use advanced autonomic nervous system testing, including the Nerve Express ANS assessment, to evaluate how your nervous system is functioning. This gives us objective data about vagal tone and autonomic balance rather than relying on symptoms alone.

What Causes Vagus Nerve Dysfunction?

Vagus nerve dysfunction doesn’t usually happen overnight. It tends to develop over time due to one or more contributing factors.

Common causes and contributors include:

• Chronic stress or trauma (physical or emotional)
• Concussion or traumatic brain injury
• Infections, including viral illnesses
• Gut dysbiosis and chronic digestive issues
• Blood sugar dysregulation
• Inflammatory conditions
• Cervical spine injuries or dysfunction
• Prolonged sedentary behavior

One of the things that makes vagus nerve dysfunction tricky is that it often doesn’t show up on standard medical tests. An MRI or blood panel may come back completely normal, even when someone is experiencing real, debilitating symptoms. This is one of the reasons so many patients go years without answers.

What Are the Symptoms of Vagus Nerve Dysfunction?

Because the vagus nerve touches so many different systems, the symptoms of poor vagal function can be wide-ranging. People with vagus nerve dysfunction often report:

• Chronic fatigue that doesn’t improve with rest
• Brain fog and difficulty concentrating
• Anxiety or a constant feeling of being “wired but tired”
• Heart palpitations or a racing heartbeat at rest
• Nausea, bloating, or slow digestion
• Difficulty swallowing
• Frequent illness or slow recovery
• Fainting or lightheadedness when standing (this can also indicate POTS)
• Low mood or depression that doesn’t have a clear trigger

Many of these symptoms overlap with conditions like dysautonomia, POTS, leaky gut, and post-concussion syndrome. That’s not a coincidence. Vagus nerve dysfunction is often a common thread running through multiple diagnoses.

How Is Vagus Nerve Dysfunction Connected to Other Conditions?

Dysautonomia and POTS. The vagus nerve is central to autonomic nervous system regulation. When vagal function is impaired, it can contribute directly to symptoms of dysautonomia, including POTS (postural orthostatic tachycardia syndrome). Many patients in the Carmel and Indianapolis area who have been diagnosed with POTS also have measurable vagal dysfunction when tested properly.

Gut and digestive issues. The vagus nerve is the primary driver of the gut-brain axis. Poor vagal signaling can disrupt the migrating motor complex (the process that clears the gut between meals), slow stomach emptying, and alter the gut microbiome. This creates a cycle where gut dysfunction further impairs vagal signaling.

Anxiety and depression. The connection between the vagus nerve and mental health is one of the most exciting areas of current neuroscience research. Because so many vagal fibers travel upward to the brain, an unhealthy gut or chronically stressed body can directly contribute to mood instability.

Concussion and mTBI. Head injuries can directly damage vagal pathways, which is one reason why post-concussion syndrome often involves digestive problems, heart rate irregularities, and mood changes in addition to cognitive symptoms.

How Does Functional Neurology Approach the Vagus Nerve?

Conventional medicine rarely looks at vagal tone as a root cause. Most standard workups don’t include any direct assessment of autonomic nervous system function, which means vagus nerve dysfunction often goes undetected.

At Nexus Neuro, we take a different approach. Dr. Matt Schulke, DC, DACNB, BCN, is a board-certified chiropractic neurologist who uses a comprehensive evaluation process to identify how your nervous system is actually functioning, not just whether your labs fall within a reference range.

Our evaluation may include:

• Nerve Express ANS testing to assess heart rate variability and autonomic balance
• NeuroAI Brain-Body Mapping, available at fewer than 15 clinics worldwide
• Video oculography (VOG) to evaluate neurological function through eye movement
• A detailed neurological history to identify contributing factors

From there, we build a personalized plan that may incorporate targeted neurological rehabilitation, SoftWave tissue regeneration therapy, PEMF therapy, and other evidence-based approaches designed to support nervous system function and improve vagal tone over time.

What Can You Do to Support Your Vagus Nerve?

While clinical evaluation and treatment is the most direct path when you’re dealing with significant symptoms, there are also lifestyle-based strategies that support vagal tone. These include:

• Diaphragmatic breathing (slow, deep belly breathing activates the parasympathetic system)
• Cold water exposure on the face or back of the neck
• Humming, singing, or gargling (these activate muscles connected to the vagus nerve)
• Regular moderate exercise
• Prioritizing sleep
• Reducing chronic stressors where possible
• Addressing gut health

These strategies are supportive, not a replacement for clinical care when symptoms are affecting your quality of life.

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Ready to Find Out How Your Nervous System Is Functioning?

If you’ve been dealing with unexplained fatigue, digestive issues, anxiety, heart rate irregularities, or other symptoms that haven’t responded to conventional treatment, your vagus nerve may be part of the picture.

Nexus Neuro: Brain + Body serves patients in Carmel, Westfield, Zionsville, Fishers, Noblesville, and the greater Indianapolis metro area. We specialize in identifying and addressing root-cause neurological dysfunction so you can actually start feeling better.

Call us at 317-884-8824 or visit nexusneurohealth.com to schedule your evaluation.