Part 4 of 4: Monitoring your vagus nerve

Welcome to part 4 of a 4 part blog on the Vagus nerve. This blog answers the question – How do I measure the happiness of my Vagus Nerve?

The short answer is via your Heart Rate Variability (HRV).  There is a much longer answer that would be a book and involve advanced knowledge of human physiology to even understand never mind write. 

Let me just summarise it in tweet-length;

we don’t know if you can measure it cause your body is crazy complex, but HRV is the best guess for vagus nerve functioning. 

Bam, 122 characters!

How do I Measure my HRV then?

This process is pretty straightforward in this modern world of apps and smartphones.  You can actually measure your HRV directly from the camera on your smartphone, using a light to ‘look’ at your blood pulsing through your fingers – how cool is that?

This technology is pretty new, or rather accurate enough versions of it are new.  When doing my PhD I used a Polar Chest strap, which is the gold standard, however, there is extra cost and fiddling about. So let’s keep it simple at talk first about the apps.

Smart Phone Apps

More apps are likely to be coming on the market – the one I use now, that I used in my PhD is HRV 4 Training.

Elite HRV is another app I trust having checked it out during my research.  The Elite HRV app still needs a chest strap (this may have changed now). However, it is super user-friendly and you can just follow hte instructions so do have a crack if you have a chest strap.  It is also FREE!

Other apps may work well enough, however, given the complexity and the many hidden processes in the background it is just hard to tell without hours of investigation.

Using HRV4Training

Open the app the first time and it will automatically step you through how to use it and get you to have a practice.  It works via simply holding your index finger firmly over the camera on your phone.

Now you are ready for your daily recordings (the more often
you measure the more power you have).  This app allows you to look at
statistical relationships between things you tell it and your HRV over time.

Measure when you first wake up (feel free to use the bathroom or have a glass of water, but avoid caffeine, food or smoking until after you record)

Try and measure at a similar time each day

Breath naturally

Measure in the same body position (i.e. if you sit one day, sit the next.  If you choose to sit – try not to slouch as it may influence recordings)

There are more specific tips to do with the app e.g. leave the flash on etc … details are here 

You can fiddle around with the app (settings<configure tags) to customise it to suit you, this one was built for hardcore athletes. Nevermind it is easy to tweak it for less hardcore athletes or even those unable to exercise much at all for whatever reasons,
but still wishing to improve their health via diet, weight loss, mediation etc.

Consistency Matters

As well as your overall health and well-being your HRV is influenced day-to-day and
even moment-to-moment by your emotions, your energy levels, your food and drink
intake or absence of, your sleep and even your water intake or lack of. 

It really is a very fragile measure – hence all the drama and hoopla going on
in research circles about what it should and should not be used for and why social
scientists (like me) should maybe have stayed the hell away from it.

What does this drama mean for you?  Well if you are looking to your trends over
time, control (make consistent) what you can.  Measure first thing in the
morning is a good idea, its usually the same sort of time.  Be in the same
position (yes it will differ in different positions and even postures), don’t
measure if you are still drunk from the night before.  

How do I stack up? What are the population norms?

If you have been brave enough to come this far and have gotten into
recording … you may start wondering how you stack up to others?

We are competitive by nature, especially in this world of instant online comparisons.  So it is obvious to consider the population norms (that is statistics speak for what is normal in those around me for this stuff).   Well although you do see overall lower statistics in people with certain illness or with varying degrees of fitness, there is also very large individual differences. 

Some experts argue that between persons comparison (boring academic-speak for comparing people against other people) is a waste of space in HRV.

The heads up is: don’t freak if you don’t fit in with the norms.  What matters is what is normal for you, which you will begin to understand over time.  It is whether your normal is on an upward or downward trend that you need to focus on, especially if you are trying lifestyle tweaks to see their effect.

Also I mentioned above how the smallest thing can alter the results, so are you comparing yourself lying down, first thing in the morning, to a group seated in the mid-afternoon.  Also, age is very important (the bad news is HRV drops off with age).

Things that might influence your HRV longer term:

  • Age
  • Gender (maybe: this one is a bit hard to know with different studies drawing
    different conclusions)
  • Diabetes
  • Heart disease
  • Kidney disease
  • Alcohol intake (not in a good way, sorry)
  • Obesity
  • Mental Illness
  • Certain meds – especially Heart Meds

Things that might mess with it on the day. Yes it can suddenly drop from its current trends due to short term triggers. Not all of which are yet understood.

  • Stress
  • Sleep
  • Time of day (rhythms)
  • Getting sick (the drop can show before you notice you are sick)
  • Recovery
  • Posture
  • Hunger
  • Overeating
  • Thirst/Drinking
  • Coffee (this one is showing up freaky strong in one of my research groups – maybe the coffee outside the research lab was a bit strong that day)
  • Freaking out that it might be low (for real)

I have RMSSD means (I am looking at a number of groups) anywhere form the late 30s to high 50s (ms).  With standard deviations in the 20s and 30s.  This is really quite a range, and supports the point about comparisons being a little funky.

If you want to compare yourself to some fit bunny quantifier types who use
the HRV apps (I sure as hell don’t) go crazy… Check them out here (also some published studies mentioned too):


This is not health advice, I am not a Medical Doctor, I am a Doctor of Philosophy.  If all this fun watching your heart raises any concerns please don’t contact me.  Contact a medical doctor.


If your HRV drops from trend one day. it may be as simple as one of the many factors mentioned above or that say you are getting a cold, or recovering from a massive session at the gym (or the pub).

But see above disclaimer – if you are at all concerned talk to anyone other than me.  Preferably a qualified medical professional.

Of course I totally ignore my own advice and freak out every time my takes a
dive … and so far I can’t pin it to anything at all.   I drink wine it goes up (it shouldn’t), I teetotal it goes down.   However I have only been in a really good routine of daily checking for a few weeks ….  I am still hoping that I’ll start having a story to tell about it soon, rather than seemingly meaningless ups and downs.

Go well in the direction of your health goals,

Yours as ever

The Wellbeingatwork(nearly)Dr

Links, References and all that Jazz

Here are all the parts in this series:

  • Part One: The Wanderer – A Brief Introduction to the
    Vagus Nerve (our Hero).
  • Part Two: How to improve the health of your Vagus
    Nerve – based on scientific evidence.
  • Part Three: Vagus nerve stimulation; can you really
    ‘gag’ your way to good health?
  • Part Four: Monitoring your own vagus nerve health using
    the variability in your heart rate.

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