Hi Friend

If you live with a chronic illness, you have almost certainly been told to track your heart rate variability.

So you bought the ring, or the strap, or you started staring at the little graph on your watch each morning. And then one of two things happened.

Either the number felt random. It jumped around in ways that made no sense against how you actually felt, high on a day you could barely lift your head, low on a day you felt fine. Or it quietly became one more thing to feel anxious about before you had even sat up in bed.

I want to explain why that happens, why it is not your fault, and what I have been doing with my patients instead. There is also a free tool at the end that I am giving everyone here access to, no catch.

First, what HRV actually is

Your heart does not beat like a metronome. The gap between one beat and the next is always shifting by tiny amounts, measured in milliseconds. That shifting is heart rate variability.

More variation is generally a good thing. It means your parasympathetic nervous system, the rest and digest side, is engaged and your body is adaptable. Less variation tends to mean your sympathetic side, the fight or flight side, is running the show and your system is braced rather than settled.

So HRV is not really a fitness metric. It is a window into the state of your autonomic nervous system on any given day.

Why this matters more for us than for anyone else

For a healthy athlete, HRV is a nice extra. For someone living with POTS, dysautonomia, ME and CFS, Long Covid, or MCAS, the autonomic nervous system is often the whole story. It is the system that is dysregulated. It is why standing up is hard, why heat floors you, why a small overreach on Tuesday costs you Thursday.

That means HRV is one of the few numbers that maps onto what is actually going wrong. Used well, it can help you see your nervous system load before your symptoms shout at you, which is the difference between pacing and crashing.

The problem is that most people are measuring it in the way that suits an athlete, not in the way that suits us.

The trouble with the overnight score

Almost every popular wearable gives you an overnight HRV figure. It measures through the night, sometimes even during the day, and hands you an average, often dressed up as a readiness or recovery percentage.

For a lot of my patients, that number is close to useless, and here is why.

Your sleep is the confounder. Fragmented, light, unrefreshing sleep is a core feature of ME, CFS and Long Covid, not a rare off night. An overnight average blends together stretches of very different nervous system states, some of them nothing like rest. You end up with a single figure built on top of disordered sleep, then you try to compare it to yesterday's figure that was built on a different kind of disordered sleep. You are comparing noise to noise.

Position moves the number. HRV changes a great deal with posture, and in orthostatic conditions that effect is amplified. Overnight, you are turning, shifting, half waking, changing position without knowing it. Every one of those movements nudges the reading. For a POTS or dysautonomia patient, that is a lot of built in interference.

It arrives too late to act on. The overnight score lands after the night has already happened. It tells you about a window you cannot change.

And it can feed the anxiety. A number that follows you around the clock, colour coded red on a bad morning, is a gift to a hypervigilant nervous system. I have watched patients spiral over a recovery score before their feet touched the floor. The measurement itself became a stressor. That is the opposite of what we want.

Why I use a spot check instead

A spot check is a short, deliberate reading taken at the same time each day, in the same position, under the same conditions. Usually first thing, lying or sitting still, before you get up, before caffeine, before you look at your phone properly.

Done this way it beats the overnight score for us on almost every count.

It is controlled, so it is comparable. Same time, same position, same conditions means today's reading and yesterday's reading are finally measuring the same thing. The trend becomes trustworthy, and the trend is where all the useful information lives. The single number barely matters. The direction of travel is everything.

It sidesteps the sleep problem. You are taking a clean reading of your nervous system in a defined moment, not averaging across a night of broken sleep.

It arrives when you can use it. A morning reading gives you a sense of your autonomic state before you plan the day. On a low morning you protect your energy. On a steadier morning you have a little more room. For anyone managing post exertional malaise, that early signal is exactly the input you want.

And it is calmer. One intentional check, then you put it down and get on with your day. That is a very different relationship with your body than a screen watching you every minute.

None of this makes HRV a diagnosis, and it does not replace your clinician or your own felt sense of how you are. It is one honest signal among several. But as a signal, a controlled morning spot check is the cleanest one I have found for this community, and it is what I have quietly been asking my patients to do for a long time now.

The free part

Here is the thing that has always bothered me. To spot check properly, most guides tell you to buy a chest strap or a subscription wearable. That is a barrier, and this community already carries enough cost and enough admin.

You do not actually need any of it. The camera on your phone can read the tiny changes in your pulse well enough to give you a proper HRV reading. So we built a simple tool that does exactly that. You sit still for a couple of minutes, hold your finger to the camera, and it takes a clean spot check for you. No strap, no ring, no monthly fee.

I am giving everyone on this list free access to it, in addition it will inlclude a daily check in such as lying and standing pulse to give you an accurate insight into your nervous system. You will be told first when this goes live.

My only ask is that you use it the way I have described. Same time each day, same position, before you get up and before caffeine. Take it for a couple of weeks before you read anything into it, because a single number tells you almost nothing and the pattern tells you almost everything. Watch the direction, not the digit.

If you have lived with the frustration of a metric that never seemed to match your body, I think this will feel different. Not because the number is magic, but because for once it is measuring you properly.

PS my mend magnesium supplements are launching in a week!! Please click HERE to be told first.

Stay Well

Dr Ahmed