A strong vagus nerve: Circadian Retraining 2.5 years in

Proper function of the vagus nerve is important to overall health. The vagus nerve helps regulate the stress response and is the communication line in the brain-gut axis. As a result, poor vagal function and lead to high stress and poor digestion.

There are a number of tips online that help promote vagal stimulation. This includes:

  • Breathing exercises
  • Gargling
  • Singing
  • Humming
  • Electrical stimulation

But this fails to address a major problem. While these exercises create vagal stimulation as you do them, the effects don’t last. And, unfortunately, to get the benefits, you really need to improve vagal function long term.

Fortunately, there are ways to measure the function of your vagus nerve. One important way that I use personally and with clients is root mean squared of the successive differences(rMSSD). And using this measure is incredibly useful for gauging success of lifestyle interventions to reverse chronic disease.

But what is rMSSD and what does it tell us?

What is rMSSD and what does it show about the vagus nerve?

Thankfully, people finally realize how important stress is to their health. As a resulf, you may have heard of heart rate variability, or HRV. HRV is a way to measure how your body responds to stress over the long term. Due to the way stress affects the body, it leaves an imprint on your physiology.

For example, if public speaking is a fear of yours, you notice how your heart begins pounding when you do it. The autonomic nervous system, or ANS, regulates automatic processes such as:

  • Arousal
  • Heart rate
  • Blood pressure
  • Immune function
  • Digestion

As a result of being under stress, one arm of your autonomic nervous system dominates the other. You know it as fight or flight, but it’s actually called the sympathetic nervous system. The sympathetic nervous system increases things like arousal, heart rate and blood pressure, while suppressing things like digestion and immune function

On the other hand, the other arm of your ANS is called the parasympathetic nervous system. It causes responses that are the opposite of the sympathetic system. Thus, it decreases arousal, heart rate, and blood pressure while improving things like digestion and immune function. You know this as rest and digest.

Often, when we are in stressful situation, we increase parasympathetic activity by breathing deeply. This helps the parasympathetic arm decrease the stress response, lowering heart rate and blood pressure. The vagus nerve is a part of the parasympathetic system, so these activities stimulate the vagus nerve.

There are many ways to measure heart rate variability, including rMSSD. But the beauty of rMSSD is that it measures vagal tone. In other words, it measures how well the vagus nerve functions.

Short term vs long term vagal function

The benefits of deep breathing, gargling, and singing on stress come by increasing stimulation of the vagus nerve. So if you are stressed, and perform these exercises, your stress should lower due to vagal stimulation.

This is incredibly useful if you’re trying to respond to an immediate stressor or want to promote digestion before a meal. If you measure rMSSD before and after an exercise like this, it would increase. This indicates that whatever you did increased activity in the vagus nerve, lowering your stress response.

You can’t really argue that this is a bad thing. But, do you want to have a hair trigger for the rest of your life? Do you want to get stressed every time you get on the train? Do you want to do 5-10 minutes of breathing exercises every time you eat? Probably not.

Therefore, it becomes critically important to improve vagal function long term. This builds resilience by allowing you to freely enter and exit the stress response. So if you generally have a low rMSSD, your long term goal should be to improve it.

There are many ways to skin that cat. But the first step is to start measuring rMSSD. The next step is to optimize circadian rhythms, because they regulate the autonomic nervous system. I covered that in a podcast you can find here. Then, there’s a lot of individual tweaking that’s involved.

I’ve been doing this for more than 30 months, and the results are nothing short of amazing. I use an app called HRV4Training, which I’ve blogged about here.

Improving vagus nerve function: From 10 years older to the fountain of youth in 30 months

When I first measured rMSSD with the HRV4Training app, I didn’t expect it to be great. But, I also didn’t think it would be awful, and it was. Based on these norms, my vagal function was similar to someone more than 10 years older than me. For reference, was 40 at the time.

HRV rmssd vagus nerve

After x years, I improved quite a bit, but was still behind the bell curve. But I stuck to my circadian schedule, making some tweaks here and there. As a result, 30 months in, I’m now in the upper 5th percentile for HRV4Training users 35 years and younger.

Given that most users of this app are athletes, I am beyond pleased. Here are my results through the years, from left to right.

As you can see, I went from a weekly rMSSD average of 34.8 to 49.6 in 6 months. However, there is great variability in the readings on the measurement from June 2018 on the right. This variability improved considerably with my next readings.

Just 4 months later, rMSSD improved by 30% and variability was considerably reduced. And 6 months after that, rMSSD was still improved with sustained low variability. At this point, my rMSSD was near the average of someone between the ages of 25-35, at an age of 42. But I wasn’t done yet.

My most recent readings are quite amazing. And had you told me I could get numbers this high in April, I would have called you a fool But here we are, in October of 2019, and at the age of 43:

rMSSD for vagus nerve function

With a weekly average of 158.9, I am in the upper 5th percentile of the “under 35” age group.

Health improvements over the last year

You may notice that huge drop from Monday to Tuesday. That drop is a result of staying up on Monday Night to watch the Patriots game until 11pm and waking up at 5:30 am for an appointment with a client. This change will negatively affect the vagus nerve no matter how good it is.

But I felt great on Tuesday and even performed pretty well when I exercised. Just 2 years ago this would have crushed me. I would have felt like garbage and probably seen some digestive issues.

But resilience in my gut is the biggest benefit I’ve seen through the years. My heart rate and blood pressure have always been great. Unfortunately, my gut not so much. I wouldn’t say I had IBS or anything like that.

But I like to consume beer on the weekends, and any time I did, loose stools quickly followed. That’s happened since my 20s, every weekend, and is no longer a problem. As you can probably guess, I track things like that.

I had 2 bouts of loose stool in 2018. The first, due to some iffy swiss cake rolls that were part of a salmonella recall(Thanks Mom). The second came about due to a very late night of staying up past midnight and drinking more than my usual beer.

This year I’ve had no issues whatsoever. I certainly consider my improved vagus nerve function as the biggest factor. But knowing what I can get away with and not doing that regularly is important as well. For example, if I’m up late drinking, I don’t drink coffee first thing the next day.


At this point I’m simply amazed at how powerful circadian rhythms are at controlling our physiology. The gut improvements are glaringly apparent, as it’s not too difficult to notice that you are no longer getting loose stools every weekend.

But I’d have no idea as to how much better my vagus nerve and autonomic nervous system are functioning without measuring rMSSD. I think people who recommend going by how you feel are really doing themselves, and others, a disservice by implying that is an acceptable way to gauge success.

I’m thrilled to see these improvements despite working at this a long time. I’m always tweaking my lifestyle to optimize my results. I’ve made considerable changes since April and they are paying major dividends.

I hope others follow suit and look for good objective measures to individualize their lifestyle. HRV4Training is incredibly useful for myself and the people I work with to get the most out of their efforts.

2 thoughts on “A strong vagus nerve: Circadian Retraining 2.5 years in

  1. Deborah Goodman says:

    Wow, I think I have vagus nerve issues but I don’t understand HRV4 training, where/how do you get this? Is it a test? Ill check out the podcast. I just found your site today and think its amazing and I have seen alot in the past 2.5 years I was poisoned by Fluoroquinolones, so I never know what my body is reponding to. Thank you.

    • cincodm says:

      Glad you’re enjoying the blog! HRV4Training is an app for heart rate variability for IOS and Android phones.

      If you search around for fluoroquinolones I’ve done a testimonial with someone who was floxed and had mitochondrial dysfunction. She uses HRV as well as Fitbit and was able to measure progress that way.

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