The nerve every biohacker is quietly obsessed with

THIS MONTH, we're talking vagal tone, the nervous system pathway every biohacker is quietly obsessed with and almost nobody explains properly.

The vagus nerve is the longest cranial nerve in the body, running from the brainstem through the heart, lungs and gut. It's the main channel of your parasympathetic nervous system.

Vagal tone measures how well that nerve does its job, how quickly you shift out of stress and back into balance. It's usually estimated through heart rate variability (HRV).

EXTEND YOUR EXHALE, the breath ratio that actually matters

Slow breathing is often prescribed as a blanket fix for stress, but the mechanism is more specific than "breathe slowly." Every time you exhale, your vagus nerve sends a braking signal to your heart, slightly slowing its rate, this is called respiratory sinus arrhythmia. Lengthening your exhale relative to your inhale (4-seconds in, 8 seconds out) maximises that vagal braking effect.

GET COLD, briefly and deliberately

Cold exposure activates the vagus nerve largely through the diving reflex, a response that evolved to conserve oxygen when the face meets cold water, slowing the heart and redirecting blood flow. Repeated, brief exposure appears to improve vagal tone over time, which is part of why cold plunging has become such a biohacking staple. The evidence is genuinely encouraging here, though the effective dose is still being worked out, brief and consistent tends to matter more than extreme.

MOVE AT A CONVERSATIONAL PACE, zone 2 and the vagus nerve

High intensity training has its place, but steady, low-intensity cardio, the kind where you can still hold a conversation, is one of the more reliable ways to improve baseline vagal tone over time. It's less about the workout itself and more about what happens afterwards: well trained cardiovascular systems recover faster, and faster heart rate recovery post exercise is itself a marker of vagal function.

USE YOUR VOICE, the larynx-vagus connection

This is the one almost nobody mentions. The vagus nerve innervates the muscles of your larynx and throat, which is why humming, singing, gargling and chanting have all been shown to stimulate vagal activity. It sounds unlikely, but the anatomy is straightforward: activating those muscles activates the nerve running through them. It's the lowest effort entry on this list, and arguably the most overlooked.

GLYCINE, the nervous system's quiet amino acid

Poor sleep is one of the fastest ways to suppress vagal tone and HRV. One of the more overlooked levers here is glycine, an amino acid that makes up around a third of collagen's structure. Small human trials suggest glycine taken before bed, typically around 3g, can improve sleep onset, deepen sleep quality and improve next day cognitive performance, largely by lowering core body temperature and quieting nervous system activity.

A daily serving of Edible Health Collagen Powder provides roughly 4g of glycine alongside 13g of highly bioavailable protein, in under 50 calories, enough to land in the range the trials used, without turning bedtime into a protocol.

BOTTOM LINE?

Most nervous system advice treats calm like something you have to force, but your vagus nerve isn't asking for extremes. It's asking for a longer exhale. A hum instead of a sigh. A short walk instead of a scroll. A proper night's sleep.

This month, we'd encourage you to think about your nervous system the way you'd think about a muscle, not something to hack once, but something to train, gently and consistently.

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