Chris Williamson with Dr. Jay Wiles, Ph.D.: Why Heart Rate Variability Isn’t About “Calm” — It’s About Nervous System Fitness

👉 Before we dive in: If you want the full conversation and deeper context, watch the original YouTube episode here. This newsletter breaks down the most important ideas—and what to actually do with them.

Who’s in This Conversation?

Chris Williamson is the host of Modern Wisdom, known for long-form conversations that bridge science, psychology, and performance.

Dr. Jay Wiles, Ph.D. is a clinical psychologist and nervous-system researcher who works with elite athletes, military operators, and high-performance teams. His specialty: understanding how the autonomic nervous system adapts to stress—and how to train it using measurable, evidence-based tools like HRV biofeedback.

The Big Reframe: HRV Isn’t a Stress Score

Heart Rate Variability (HRV) has become one of the most misunderstood metrics in health.

HRV is NOT a measure of how stressed you are.
It’s a measure of how well your nervous system adapts to stress.

Think of HRV as:

• A signal of resilience

• A proxy for nervous system flexibility

• A reflection of how efficiently your body shifts between energy use (sympathetic) and recovery (parasympathetic)

Low HRV doesn’t mean you’re “broken.”
High HRV doesn’t mean you’re “elite.”

What matters most is your trend over time, not how you compare to someone else’s Whoop screenshot on Instagram.

One of the Most Overlooked Truths About HRV

A “good” HRV is often a stable HRV.

Most people assume HRV should constantly go up. According to Dr. Wiles, that’s wrong.

Large day-to-day swings in HRV can actually signal:

• Excess stress

• Poor recovery

• Nervous system instability

In elite sports and clinical settings, one of the most valuable metrics isn’t HRV itself—it’s how much your HRV fluctuates from day to day.

Stability = adaptability.

Why Everyone’s HRV Is So Different (and Why That’s Normal)

Your HRV is heavily influenced by factors you cannot control:

• Age (HRV tends to decline starting in the mid-30s to 40s)

• Genetics

• Sex differences (men average higher HRV than women, partly due to hormonal cycles)

• Body size & cardiovascular structure

This is why comparing HRV between people is meaningless.

A 40-year-old with an HRV of 35 who is trending upward and stable may be adapting far better than a 25-year-old sitting at 120 and declining.

The Single Most Important Concept Most People Miss

State Change vs. Trait Change

• State change = how you feel right now
  (calm, relaxed, less anxious)

• Trait change = how your nervous system adapts over weeks and months

Most breathwork, meditation, and relaxation techniques only create state change.

Dr. Wiles emphasizes that only one breathing approach consistently shows trait-level nervous system changes in the research:

👉 Resonance Breathing (HRV Biofeedback)

Why Resonance Breathing Is Different

Resonance breathing involves slow, precise breathing (usually ~4.5–6 breaths per minute) that synchronizes:

• Heart rate

• Breathing

• Blood pressure regulation (baroreflex)

This creates a powerful training effect for the vagus nerve and autonomic nervous system.

Key difference:
This isn’t about “feeling calm.”
It’s about training your nervous system like a muscle.

Dr. Wiles calls it:

“Going to the nervous system gym.”

How Fast Does It Work?

• Immediate effects: seconds to minutes
  (your nervous system responds almost instantly)

• Trait-level changes:

  • As little as 4 weeks

  • Most people see meaningful change around 8–10 weeks

  • Requires consistency

You cannot fake regulation during sleep—which is why improvements often show up there first.

Why Sleep Is the Canary in the Coal Mine

Sleep is where nervous system health shows up most clearly.

When the nervous system is dysregulated:

• Sleep becomes fragmented

• Deep restorative sleep drops

• Night-time stress responses increase

Resonance breathing before bed has strong evidence for:

• Improving sleep quality

• Reducing nighttime nervous system “spikes”

• Increasing overnight recovery signals

If sleep isn’t improving, it’s often a sign the nervous system still isn’t adapting.

ACTIONABLE TAKEAWAYS (What to Do Differently After This Episode)

1. Stop Treating HRV Like a Scorecard

• Don’t compare your HRV to others

• Track your baseline and stability over time

• One low reading means nothing

2. Train the Nervous System (Don’t Just Relax It)

If you want real change:

• 10–20 minutes of resonance breathing

• 4–6 days per week

• One continuous session (not broken into tiny chunks)

Short sessions help in the moment.
Longer sessions create adaptation.

3. Use Breathing Strategically

• Before bed: improve sleep and recovery

• After workouts: downregulate faster

• Before stressful events: quick state regulation

You don’t need to “feel calm” for it to work.

4. Pair Nervous System Work With Fitness

The two biggest levers for improving HRV:

• Cardiorespiratory fitness (Zone 2 + some high-intensity work)

• Dedicated nervous system regulation

Think of HRV improvements as a byproduct of better systems—not the goal itself.

5. Don’t Ignore Subjective Feel

Data matters—but so does this question:

“Do I feel more resilient than I did a month ago?”

Shorter fuse, worse sleep, constant irritation = signs something’s off, regardless of your wearable score.

Bottom Line

HRV isn’t about winning a leaderboard.
It’s about building a nervous system that can handle life without constantly being stuck in high alert.

This episode reframes HRV from a confusing number into something trainable, practical, and deeply connected to sleep, stress, and long-term health.

If there’s one takeaway to remember:

You don’t need to eliminate stress. You need a nervous system that can adapt to it.

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