Vagal Tone & The Art of Letting Go: Why Your Brain Won't Let You Relax

You've tried everything.

Meditation apps. Breathing exercises. "Just relax" advice from well-meaning friends. But your body won't cooperate. Your mind races. Your shoulders stay tense. You're exhausted, yet wired.

You know that feeling when you're trying to unwind, but your brain just... won't? Like you're pushing against a door that's locked from the inside?

Here's what's actually happening: your brain's threat detection system is overriding your relaxation attempts. And honestly? It's not a willpower problem, it's a nervous system architecture problem.

The thing is, the solution isn't trying harder to relax. It's understanding how your vagus nerve works, and why it might not be "toned" enough to let you truly let go.

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What Is Vagal Tone, Really?

Vagal tone refers to the activity of your vagus nerve, the longest cranial nerve in your body, running from your brainstem through your heart, lungs, and digestive system. Think of it as your body's "brake pedal" for stress.

When your vagal tone is high, your nervous system can quickly shift from "fight-or-flight" (sympathetic) to "rest-and-digest" (parasympathetic). When it's low, you get stuck in stress mode, even when there's no actual threat.

Here's the key insight: vagal tone isn't something you're born with and stuck with. It's trainable. It's responsive. And chronic stress can deplete it over time, leaving you unable to access calm even when you desperately need it.

The Science: HRV as a Window Into Your Nervous System

Heart rate variability (HRV) is the most accessible measure of vagal tone. Honestly? It's kind of like having a dashboard for your nervous system.

HRV refers to the natural variation in time between heartbeats, when your heart beats 60 times per minute, it's not exactly once per second. Some intervals might be 0.9 seconds, others 1.1 seconds. That variability is healthy. Think of it like a jazz drummer versus a metronome: the metronome is perfectly uniform (low HRV), but the jazz drummer has rhythm and flow (high HRV).

Higher HRV = stronger vagal tone = better stress resilience.

During stress, your sympathetic nervous system takes over, making your heart rate more uniform (lower HRV). Your vagus nerve essentially "withdraws," releasing the brake on your stress response. In recovery, vagal activity rebounds, increasing HRV back toward baseline.

A meta-analysis of 37 studies confirmed this pattern: psychological stress reliably suppresses vagal-HRV metrics. The research is clear: when you're stressed, your HRV drops. When you're truly relaxed, it rises.

But here's where it gets interesting: not everyone recovers equally. Some people show rapid vagal rebound after stress, their HRV quickly returns to baseline. Others show blunted recovery, staying stuck in a low-HRV, high-stress state. This difference in recovery speed is a key marker of resilience. It's like the difference between someone who bounces back from a hard workout versus someone who's still exhausted three days later.

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Why "Just Relax" Doesn't Work

Your brain has a primitive threat detection system that operates below conscious awareness. When this system perceives danger (real or imagined), it activates your sympathetic nervous system increasing heart rate, tensing muscles, sharpening focus.

The problem? This system can't distinguish between a real threat and perceived stress. A work deadline triggers the same physiological response as a saber-toothed tiger. And once activated, this system doesn't just "turn off" because you tell it to relax.

Your vagus nerve is the counterbalance—the system that signals "safety" to your primitive brain. But if your vagal tone is depleted from chronic stress, that safety signal never arrives. Your brain stays on high alert, even when you're trying to meditate or breathe deeply.

This is why relaxation techniques sometimes feel like pushing against a wall. You're trying to activate your parasympathetic system, but your vagal tone isn't strong enough to override the sympathetic dominance.

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How Kanna Supports Vagal Tone: The Science

The thing is, kanna doesn't magically "fix" your vagal tone. But it does something pretty cool: it helps create the conditions where your vagus nerve can actually do its job.

Kanna (Sceletium tortuosum) contains mesembrine alkaloids that work through two primary mechanisms relevant to nervous system regulation:

1. PDE4 Inhibition: Quieting the Alarm

Kanna inhibits phosphodiesterase-4 (PDE4), an enzyme in your brain that breaks down cyclic AMP (cAMP). When PDE4 is inhibited, cAMP levels increase—supporting memory, learning, and cognitive function.

But here's the connection to vagal tone: PDE4 inhibition also modulates stress pathways. Research shows that PDE4 inhibitors can reduce anxiety and stress reactivity by influencing how your brain processes threat signals. Think of it like turning down the volume on your brain's alarm system. By quieting the "alarm" in your brain, kanna may help your vagus nerve do its job more effectively. Less noise, more signal.

2. Mesembrenol: Signaling Safety to the Primitive Brain

The mesembrine alkaloids in kanna (particularly mesembrenol) act as serotonin reuptake inhibitors. This isn't just about mood. Serotonin plays a crucial role in signaling safety to your primitive brain. It's like sending a message to your security guard: "Hey, we're good here. You can stand down."

Functional MRI studies show that kanna can reduce hyperactivity in the amygdala—your brain's fear center. When your amygdala is less reactive, your threat detection system calms down. This allows your vagus nerve to engage more easily, shifting you from sympathetic dominance to parasympathetic activation. It's like clearing the static so the signal can come through clearly.

In one randomized, placebo-controlled study, healthy volunteers given a standardized kanna extract (25 mg Zembrin®) showed significantly lower anxiety ratings and a smaller rise in heart rate during a public speaking stressor. Their autonomic response stayed more stable under stress—suggesting better vagal preservation. Essentially, their brake pedal worked better under pressure.

The takeaway: Kanna doesn't directly increase HRV or vagal tone. Instead, it supports the conditions that allow your vagus nerve to function optimally, by reducing threat reactivity and signaling safety to your primitive brain. It's not doing the work for you, but it's clearing the path so you can do the work yourself.

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Practical Exercises to Increase Vagal Tone

Vagal tone is trainable. Here are evidence-based practices that can strengthen your vagus nerve's ability to shift you into relaxation:

1. Slow, Deep Breathing (6 Breaths Per Minute)

The most direct way to activate your vagus nerve is through slow, controlled breathing. Research shows that breathing at approximately 6 breaths per minute (about 5 seconds in, 5 seconds out) stimulates the barorefle, a mechanism that activates vagal pathways.

How to practice:

• Inhale slowly for 5 seconds
• Exhale slowly for 5 seconds
• Repeat for 5-10 minutes
• Focus on diaphragmatic breathing (your belly should rise on inhale)

A meta-analysis of 223 studies found that slow breathing exercises reliably increase HRV and promote parasympathetic activation. This isn't woo-woo—it's physiology. The science is pretty cool, actually.

2. Humming, Singing, or Chanting

Your vagus nerve innervates muscles in your throat and sinuses. Activities like humming, singing, or chanting activate these muscles and stimulate vagal pathways.

How to practice:

• Hum a single note for 30-60 seconds
• Feel the vibration in your throat and chest
• Notice your heart rate slowing
• Repeat 3-5 times

This is why many meditation traditions incorporate chanting or humming—they're literally stimulating your vagus nerve. (Who knew monks were onto something?)

3. Cold Exposure

Splashing cold water on your face or taking a cold shower can trigger the "diving reflex"—a vagal response that slows heart rate and increases HRV.

How to practice:

• Splash cold water on your face for 30 seconds (while seated)
• Or end your shower with 30 seconds of cold water
• Focus on slow, controlled breathing during the exposure

Important: Start gradually and listen to your body. Cold exposure isn't for everyone, especially those with cardiovascular conditions.

4. Social Connection and Laughter

Positive social interactions trigger oxytocin release, which can increase vagal activity. Genuine laughter and feeling safe in social connection can spur parasympathetic surges.

How to practice:

• Spend time with people who make you feel safe and seen
• Engage in activities that bring genuine joy
• Practice gratitude for your relationships

The polyvagal theory (developed by Stephen Porges) emphasizes that social engagement is a natural vagal stimulant. Your nervous system is designed to calm down when you feel safe with others.

5. Regular Aerobic Exercise

Exercise increases cardiac vagal tone over time. Meta-analyses show significant increases in resting HRV with regular cardio training.

How to practice:

• Aim for 150 minutes of moderate aerobic exercise per week
• Even brisk walking counts
• Consistency matters more than intensity

The key is regular movement—not occasional intense workouts. Your vagus nerve responds to consistent training.

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The "Vagal Tank" Theory

Think of your vagal tone like a tank that can be filled or drained. (Honestly, this metaphor works better than you'd think.)

• Resting HRV = how full your tank is by default
• HRV reactivity = how much your tank drains during stress
• HRV recovery = how quickly your tank refills after stress

Someone with high resting HRV (a full tank) might still struggle if they have poor recovery (slow refill). Someone with lower resting HRV but excellent recovery might handle stress better than their baseline suggests. It's like having a smaller gas tank but better fuel efficiency—you might get further than someone with a bigger tank but terrible mileage.

The goal isn't to maximize HRV indefinitely—it's to optimize all three aspects: resting tone, stress reactivity, and recovery speed. It's about building a system that works for you, not chasing a number.

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What Backfires: Habits That Deplete Vagal Tone

Let's be real: not all "relaxation" strategies actually help. Some common habits actually hinder vagal tone. (And honestly? This might explain why you're still exhausted.)

Alcohol: Even one drink can reduce nighttime HRV recovery by ~9%. Alcohol impairs parasympathetic rebound during sleep—the critical period when your body should be recovering. That nightcap? It's not helping you unwind, it's stealing your recovery.

Excess Caffeine: Caffeine increases sympathetic drive, decreasing HRV. Using caffeine to cope with stress keeps your body in a pseudo-stress state, preventing vagal engagement. It's like trying to relax while your foot is on the gas pedal.

Late-Night Screen Time: Blue light suppresses melatonin and keeps your sympathetic system engaged when it should be winding down, leading to lower HRV overnight. Your brain thinks it's daytime, so it stays alert. Not exactly conducive to rest-and-digest mode.

Sedentary Coping: Complete inactivity can reduce baseline HRV. Light movement is more effective at restoring autonomic balance than endless scrolling. Your body believes movement faster than it believes pep talks.

Smoking/Nicotine: Nicotine triggers sympathetic surges, acutely lowering HRV. Chronic smoking blunts vagal reflexes over time. It might feel calming in the moment, but it's actually keeping you stuck in stress mode.

The pattern is clear: stimulants and sedatives that feel relaxing often impair your body's natural recovery mechanisms. It's like borrowing from tomorrow's energy to get through today—except tomorrow always comes.

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Putting It Together: A Nervous System Architecture Approach

The 2026 shift in wellness messaging is moving from "stress relief" to "nervous system architecture." This framing acknowledges that relaxation isn't a switch you flip—it's a system you build.

Your vagus nerve is central to this architecture. When it's toned and responsive, you can shift between states fluidly. When it's depleted, you get stuck.

The practices above—breathing, movement, social connection—are like workouts for your relaxation response. They strengthen your vagal tone over time, making it easier to access calm when you need it.

Kanna can support this process by reducing threat reactivity and signaling safety to your primitive brain. But it's not a replacement for vagal training—it's a tool that helps create the conditions for your nervous system to function optimally.

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The Bottom Line

If your brain won't let you relax, it's not a character flaw. It's a nervous system architecture issue.

Your vagus nerve needs to be toned—trained, strengthened, supported—to effectively shift you from stress to calm. This happens through consistent practices that activate vagal pathways: slow breathing, movement, social connection, and other evidence-based techniques.

Understanding vagal tone reframes relaxation from "trying harder" to "building capacity." It's not about forcing calm—it's about creating the physiological conditions that allow calm to emerge naturally.

And once you've felt that shift—that moment when your shoulders drop, your breath deepens, and your nervous system finally lets go—you'll understand why vagal tone matters. It's the difference between performing relaxation and actually experiencing it.

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If You're Curious

If you're interested in exploring how kanna might support your nervous system architecture, start with understanding your own patterns:

• Track your HRV trends (using a wearable or morning measurements)
• Notice what practices increase your sense of calm
• Pay attention to what depletes your recovery

The thing is, everyone's nervous system is different. What works for your friend might not work for you. The goal isn't to copy someone else's routine—it's to discover what helps your body feel safe and grounded.

For those using kanna as part of a nervous system support routine, the Unwind hub offers a framework for integrating botanical support with vagal training practices.

To learn more about the science behind kanna, visit our research overview. For a comparison of how kanna and CBD support nervous system regulation differently, see Kanna vs. CBD.

Join the gK Journal for more insights on nervous system architecture, vagal tone, and evidence-based practices for true relaxation. (We promise it's less annoying than your ex's Instagram stories.)

— With love, gK

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References & Further Reading

• Kim, H.-G., et al. (2018). Stress and heart rate variability: A meta-analysis and review of the literature. Psychiatry Investigation, 15(3), 235–245.

• Laborde, S., et al. (2018). Vagal tank theory: The three Rs of cardiac vagal control functioning – Resting, reactivity, and recovery. Frontiers in Neuroscience, 12, 458.

• Reay, J., et al. (2020). Sceletium tortuosum (Zembrin®) ameliorates experimentally induced anxiety in healthy volunteers. Human Psychopharmacology: Clinical and Experimental, 35(6), e2753.

• Goessl, V. C., et al. (2017). The effect of heart rate variability biofeedback training on stress and anxiety: a meta-analysis. Psychological Medicine, 47(15), 2578–2586.

• Shaffer, F., et al. (2014). A healthy heart is not a metronome: An integrative review of the heart's anatomy and heart rate variability. Frontiers in Psychology, 5, 1040.