Part 4 of 4: Do try this at home; monitoring your own vagus nerve

Welcome to part 4 of a 4 part blog on the Vagus nerve.

Here are the parts:

  • 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: Do try this at home; monitoring your own vagus nerve health using the variability in your heart rate.

polarh7How 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 a best guess for vagus nerve functioning.  Bam 122 characters!

How do I Measure my HRV?

This process is pretty straight forward in this modern world of apps and smart phones.  You can actually measure it directly from the camera on your smart phone (that uses a light to ‘look’ at your blood pulsing through your fingers – how cool is that shit?). Although a super tech head I respect in this area describes it as ‘a bit technical’, to actually get it working usefully.  Think weight lifter warning you the box you are about to lift is ‘a bit heavy’.  If you are feeling brave and don’t want to invest in any new technology; I refer you directly to Marco for more:

There are probably more user friendly ways – but I suspect the results might not be useful.  I shall leave this here as this is not my area of expertise.  (Note from the future, things have moved on a bit here and it looks like the smart phone technology is easier, more accurate etc – hell Siri can probably set it up for you).

My preferred approach is to use a chest strap with a good quality app (note from the future – still my preferred approach but maybe that is my version of slow food).  I used the Polar H7 Heart Rate Monitor (shown in a range of colours to co-ordinate with your ‘active wear’).  I use this as it has been used in research, is good quality and affordable, you can purchase online at any major online retailer.

To try monitoring your HRV at home what you will need is:

  1. A chest strap
  2. A mobile device
  3. An app

NOTE: It is important that all three will talk to each other. For the polar H7 monitor your mobile device needs talk smart Bluetooth (bluetooth 4.0). The Polar Website provides a list of compatible devices.  Check it out first.  I don’t want you having to invest in a new device as I did after ordering the monitor and it not talking to my (old) Samsung tablet.

I am going to cover two apps as they are the ones I have used in my research and at home.

Elite HRV app (free)

hrveliteThe Elite HRV app is nifty and user friendly.  It is something you can jump into with no knowledge on HRV.  It steps you through it, provides you what you need.  There are graphs for trends and it holds your hand through the recording process etc.  It also has a very nice paced breathing tool with some lovely (optional) voices to guide you (and allow you to close your eyes if you prefer).

The big challenge with HRV is the results/outputs are so very technical and complex. I am still trying to understand them after several years reading about it (but I might be a bear of small brain compared to you so stress not my friend).

The Elite guys (who are most certainly bears of big brains) take that drama out of it with a simple dial/traffic light type dashboard (see image for how well I am doing today).  It gives you one number for HRV (out of 100).  The down side is this number is not something official or used in the research. It is something they have used to make it more user friendly.

In the research HRV has a range of different measures in the time domain, the frequency domain and some other really scary ones.  Some of the measures you will see are RMSSD, PNN50, HF, LF, HF/LF Ratio.  It really gets crazy complex.  However if you are a real life hacker and want to start comparing yourself to published data you will want some of this.  Elite does provide you with, probably the most common one, RMSSD.  This is based on the standard deviation and some fancy maths, specifically the root mean squared standard deviation of the R-R intervals of your PQRS complex – I know – WTF?  Don’t worry about it …. see it as “how variable is my heart rate?” … and remember higher numbers are better (more variability).

The other slight warning is the lovely dashboard image has arguably jumped the research gun a little …… as pealing down a few layers there is real debate about which measures (if any) indicate anything about which branches of the Autonomic Nervous System. But even knowing this I love to look at it every morning and get all emotional about it.

So to get started, just down load it.  Connect your monitor. Turn on the blue tooth on your hand held device and follow the instructions …. too easy… (that’s a thing we say here all the time – I’m not really sure why).

HRV Logger (small fee)

HRV logger is also simple to use just connect and push go.  However there is not the functionality to make sense of your data in the same way as Elite HRV.  It is a bit more for the more serious hackers.  It provides all that scary tech stuff I was talking about above and much much more.  To track your trends or turn it into a dash board/graph type thing – you will need to do this yourself.  The good news is the export (to drop box) functionality is there for you.   As is free software online to allow you to write a PhD on your progress, or start your own blog (if I can, anyone can).

Below are some instructions I gave research participants on using the HRV logger who had never done anything like this before.  So this one should help if you are stuck or having difficulty figuring it out yourself, or like me older than 40 and get all freaked with all this “intuitive” modern technology that isn’t for the over 40s.

These instructions assume the app is already loaded on your (compatible) hand held device.

HRV Logger Step-by-Step How to:








  1. Wet (just a little spray of water, or just lick it will do – I know – eeeww) and attach the Polar H7 Heart Rate Monitor. Put the monitor firmly placed and in the middle of your chest, around where your ribs meet up, with the rubbery black bit touching your skin, and the monitor in the middle.
  2. Get your watch or open the breathing app (if timing your breathing – see below for more).
  3. Sit in an upright position, legs uncrossed, reasonably still and relaxed (or whatever your chosen daily reading position is mine is actually lying flat or ‘supine’ as it is properly called.)
  4. Open the HRV logger app on your mobile device
  5. Select the “connect” button (see image) – sometimes it will have connected automatically. If it is not connecting try these:
    • Check your Bluetooth is on
    • Tighten or adjust your strap
    • Add more water (or licky-ness) to your strap
    • Turn the app off and on again
    • Turn the device off and on again (I could be a help desk operator)
  6. Label the recording in the box (you need to be connected first or it deletes).
  7. Select the “record” button
  8. Remember to remain still and avoid talking during the recording
  9. Record for 3-5 minutes
  10. Press the “stop” button

Now you have the data – you can simply leave it in the device you recorded it in and enjoy looking through (via the history button).  Perhaps show your boss in your next appraisal meeting, your mother-in-law next time she comes over to check on your borders, the guy next door, post it on Facebook – no one will get it and you can feel all special and misunderstood….nice….welcome to my life.

Or perhaps you can upload it to drop box (instructions within app). This will provide a range of files with all your raw data; excel files, text files and access database files.  However even the gurus won’t make much sense of the raw data.  You need to download Kubios or something similar. Kubios is free software built by a PhD student to analyse HRV data (that’s what PhD students do because no-one taught them how to sell stuff and be the next Bill Gates).

However this is quite a level of commitment as last I saw the site was down and you need to email a request for the software.  Update – there is a new version coming – you can get updates on their facebook page.

If you do get it sorted that far, just look at how neat it is (and this is the old version).  The downside again is you can’t see trends over time this is the analysis of one recording.


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.   Another thing is what to do with your breathing while measuring……

To Pace or Not to Pace: That is the Question?

Something to consider, regardless of the tools you use is how to breathe? You thought you had breathing under control – oh no.  Well it turns and there is a complex and intricate relationship between your breathing and your heart rate (see previous blogs).

Slowing your breathing down as a sort of meditation type technique might just improve your HRV.

The big question is will you get a better measure of your HRV if you follow a breathing pacer or just breathe oh naturale ….. well there has been a bit of flip flopping and mind changing on this.   So lets us not wade into the debate and instead focus on consistency. Choose something and stick with it.

paced-breathingI personally pace – because it is a wonderful form of multi-tasking.  I get my daily measure and a few minutes of paced breathing done in one.   I find that I am now almost incapable of not pacing my breathing in any case  … breathing naturally while measuring is lost to me.

If you are using the Elite HRV app the pacer is built in.  If you choose HRV logger you will need a breath pacer (loads of free ones in the app stores).   Or simply a watch or clock with seconds hand. Then breath in for 5 and out for 5 seconds.


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 (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.

CompareThe 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

  • Stress
  • Sleep
  • Time of day (rhythms)
  • Getting sick
  • Recovery
  • Posture
  • Hunger/Over eating
  • 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)

In terms of what I am seeing in my research, clearly I’ll need to keep it vague as I don’t want to have all my thunder stolen or get done for plagiarizing my own blog later when I publish.

So very loosely using a sitting measure, with a mix of paced and un-paced breathing (paced should be higher and indeed seems to be), 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.

My personal lying morning RMSSD is usually in the 30s, which potentially puts me well below my research participants. (Update I am several years older since the writing of this and it is now early 50s, yippee).

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


This is not health advice, I am not a Dr, I am not even nearly a Doctor … I am nearly a Doctor of Philosophy which is almost completely useless …. and not even that nearly unless my statistics start behaving.  If all this fun watching your heart raises any concerns please take them to your doctor.   However although there are links between HRV and more serious heart issues you need 24 hour recording to get into that and I don’t even know anything about them.


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













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