The Vagus Nerve: From Ancient Mystery to Modern Wearable

For a nerve most people had never heard of a decade ago, the vagus nerve has quite a story — mistaken for a spiritual channel, credited with the first-ever discovery of a neurotransmitter, wired into a surgical implant, and now built into wearables you can order on Amazon.

4 min read

What is the vagus nerve?

The vagus nerve is the tenth cranial nerve, and by most measures the longest and most complex one in the human body. It runs from the brainstem, through the neck, and down into the chest and abdomen, touching along the way the heart, lungs, and digestive system. As the primary channel of the parasympathetic nervous system — the "rest and digest" side of your nervous system, as opposed to "fight or flight" — it plays a role in regulating heart rate, breathing, and digestion, while also carrying sensory information from your organs back up to the brain.

In other words: it's less a single wire and more a two-way communication highway between your brain and the rest of your body.

Ancient origins: a 2,000-year-old mystery

The vagus nerve's name comes from the Latin word for "wandering" — a fitting description for a nerve that meanders through nearly every major organ system. Physicians in ancient Greece, including Galen, already had a rough idea that it was involved in breathing and voice control, though its full path through the body wasn't understood yet.

For a long stretch of history — well into the Middle Ages — the vagus nerve was viewed as something closer to a mystical connector between body and soul than a biological structure with a defined function. The name "vagus" itself wasn't formally written down until around 1611, by the anatomist Caspar Bartholin the Elder. It would take a few more centuries of anatomical study, from Vesalius onward, to map it with real precision.

The 1921 discovery that changed neuroscience

The vagus nerve's biggest scientific moment arguably has nothing to do with wearables or implants — it happened in a lab, with two frog hearts, in 1921.

Physiologist Otto Loewi ran an experiment where he electrically stimulated the vagus nerve of one frog's heart, then transferred the fluid surrounding it to a second, unstimulated frog heart. The second heart slowed down too — meaning the vagus nerve wasn't just sending an electrical signal, it was releasing a chemical messenger. Loewi called this substance "Vagusstoff." It was later identified as acetylcholine: the very first neurotransmitter ever discovered. The finding was significant enough to earn Loewi, along with Henry Dale, the Nobel Prize in Physiology or Medicine in 1936.

From lab to operating room: the invasive era

The idea of deliberately stimulating the vagus nerve for therapeutic purposes goes back further than you'd expect — a 19th-century New York neurologist named James Corning experimented with it as a possible treatment for seizures. But the idea didn't really take off until the 1980s, when researcher Jacob Zabara built an implantable device — originally called a "neurocybernetic prosthesis" — and tested it in animal studies for seizure control.

That research led to the first vagus nerve stimulator implanted in a human in 1988, which reduced seizure frequency in the majority of patients in the initial trial. In 1997, the FDA approved the first implantable VNS device for treatment-resistant epilepsy in patients over 12 — a surgical procedure involving a pulse generator implanted in the chest, wired to an electrode wrapped around the vagus nerve in the neck. The therapy was later approved for treatment-resistant depression, and its use was extended to younger patients in 2017.

It's effective, but it's also major surgery — which is exactly why researchers kept looking for a way to reach the vagus nerve without opening anyone up.

The non-invasive breakthrough

That search led to transcutaneous vagus nerve stimulation — delivering a gentle electrical signal to a branch of the vagus nerve through the skin, with no surgery required. The first version to gain real traction stimulated the ear (transcutaneous auricular VNS, or taVNS), since a branch of the vagus nerve sits close to the surface there. For the first time, VNS looked like something that could be safe, affordable, and used at home — not just in an operating room.

From there, the same non-invasive principle expanded to the neck itself, where the vagus nerve runs closer to the skin's surface than almost anywhere else in the body. This is the category of device — non-invasive, cervical (neck-based) stimulation — that products like Nervelo belong to today.

Where Nervelo fits in

Nervelo is part of this newer generation of non-invasive, hands-free wellness wearables, built for a simple daily ritual rather than a medical procedure: no surgery, no clinic visit, just a few minutes worn around the neck, morning and night. It's designed to support relaxation, sleep, and everyday calm — not to diagnose, treat, cure, or prevent any medical condition.

What's changed since 1988 isn't the nerve — it's how accessible working with it has become.