What Your Heart Rate Variability Says About Your Health
By: Brian Hoeflinger, MD
August 3, 2025 | #56
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Disclaimer: Opinions are my own. Not medical advice.
Medical Trivia of the Week
Which brain region plays a critical role in error detection and adaptive behavior, often activated during moments of conflict or decision-making? (the correct answer is at the end of this email)
- A) Hippocampus
- B) Anterior cingulate cortex
- C) Amygdala
- D) Broca’s area
Information Hidden in Your Heartbeat
Your body is talking to you, even when you're just sitting still. One of the clearest messages it sends is through your heartbeat.
But we’re not talking about how fast or slow your heart beats. We’re talking about how much it varies from beat to beat. And this subtle variation, called Heart Rate Variability or HRV, might be one of the most important indicators of your health, resilience, and longevity.
Let’s break it down.
What Is Heart Rate Variability (HRV)?
Heart Rate Variability is the variation in time between heartbeats.
If your heart beats 60 times per minute, you might assume it beats once every second. But that’s not exactly true. In a healthy person, the time between beats actually fluctuates, perhaps 0.95 seconds between two beats, then 1.05 seconds between the next.
That variation is a sign of a responsive, adaptable nervous system. And that’s exactly what we want.
HRV is regulated by the autonomic nervous system, which has two branches:
- Sympathetic (“fight or flight”)
- Parasympathetic (“rest and digest”)
A high HRV means your body is smoothly balancing between these two systems. A low HRV can mean the body is stuck in a stress state or struggling to recover.
Why HRV Matters
High HRV is associated with:
- Better cardiovascular health
- Greater emotional resilience
- Stronger immune function
- Reduced risk of anxiety and depression
- Better sleep quality
- Faster recovery from exercise or illness
- Longer lifespan
Low HRV, on the other hand, is associated with:
- Chronic stress
- Fatigue and burnout
- Poor recovery
- Higher risk of heart disease and mortality
In clinical settings, low HRV can even signal early warning signs of issues like sepsis, overtraining syndrome, and autonomic dysfunction.
HRV as a Window Into Your Nervous System
Think of HRV like a stress thermometer. The more adaptable your nervous system is to your environment, the more your HRV reflects that.
For example:
- High HRV: You’re calm, well-rested, emotionally balanced, and physically recovered.
- Low HRV: You’re overworked, anxious, underslept, or possibly getting sick.
Many modern wearable devices (like Garmin, WHOOP, Oura, and Apple Watch) now measure HRV daily, providing valuable feedback on your body’s internal state.
How to Improve Your HRV
You can’t directly control your HRV like you can your heart rate, but you can train your nervous system to be more balanced and resilient. Here’s how:
1. Prioritize Quality Sleep
- Deep, uninterrupted sleep is one of the biggest contributors to high HRV.
- Aim for 7–9 hours per night in a dark, cool, quiet room.
- Stick to a consistent bedtime and avoid screens an hour before bed.
2. Practice Box Breathing
-
This is a simple technique that calms your nervous system:
- Inhale for 4 seconds
- Hold for 4 seconds
- Exhale for 4 seconds
- Hold for 4 seconds
- Repeat for 2–5 minutes daily (or during stressful moments).
- Studies show that slow, controlled breathing increases parasympathetic activity and improves HRV.
3. Try Meditation or Mindfulness
- Even 10 minutes a day can lower stress hormones and increase HRV.
- Apps like Headspace or Insight Timer make it easy to build the habit.
4. Move Your Body
- Regular aerobic exercise (walking, biking, running) supports long-term HRV gains.
- Be mindful of overtraining, excessive workouts without recovery can drop HRV significantly.
5. Get Outside and Soak Up Nature
- Natural environments reduce cortisol and activate your parasympathetic system.
- Morning sunlight also helps regulate circadian rhythm, improving sleep and HRV.
6. Stay Hydrated and Eat Real Food
- Dehydration and inflammation can suppress HRV.
- Eat a balanced diet rich in whole foods, omega-3s, and antioxidants.
7. Avoid Alcohol (or Drink Less)
- Alcohol, even in moderate amounts, can sharply decrease HRV for 1–2 days.
- One study found a single night of drinking lowered HRV by over 20%.
Your HRV Is Yours
HRV is highly individual. What’s considered “good” for one person may be different for another. Instead of comparing to others, look for trends over time:
- Is your HRV improving?
- Do you notice lower HRV when you're stressed, sick, or underslept?
- Can you use HRV as feedback to adjust your habits?
Over time, higher HRV means you’re building a more resilient, adaptive body and mind.
Listen to the Signals
We often ignore subtle signs of stress, burnout, or imbalance, until our body forces us to pay attention.
HRV gives you the chance to hear those signals earlier. To recover before you crash. To rest before you break down. To breathe before you snap. It’s a small metric with a powerful message: Take care of your nervous system, and it will take care of you.
Impactful Quote of the Week
"It’s not the load that breaks you down, it’s the way you carry it."
- Lou Holtz
All my best,
Brian Hoeflinger
P.S. - if you enjoyed this newsletter, you may enjoy my book that details my life as neurosurgeon and the loss of my oldest son, Brian (see below a synopsis).
Check out My Book
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Medical Trivia Answer:
The correct answer is B) Anterior cingulate cortex
*Disclaimer: This newsletter and blog is for general informational purposes only and does not constitute the practice of medicine, nursing, or other professional health care services, including the giving of medical advice, and no doctor/patient relationship is formed. The use of information on this newsletter and blog or materials linked from this newsletter and blog is at the user’s own risk. The content of this newsletter and blog is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Users should not disregard or delay seeking medical advice for any medical condition they may have and should consult their healthcare professionals for any such conditions.
