Ah, what a trifle is a heart, If once into love's hands it come
When it comes to the nervous system, there are voluntary and involuntary parts. We can reach out and grab something, or decide to walk from here to there, but we don’t have voluntary control over our digestion, goose bumps, how fast the heart beats, or our blood pressure. That involuntary (or autonomic) nervous system is also divided into two parts, the sympathetic (fight or flight) and parasympathetic (rest and digest).
Though this is simplified somewhat, a core issue with people suffering from clinical anxiety and depression is that their fight or flight nervous system is tuned way high and the parasympathetic capability shrinks down and doesn’t stage a robust recovery after what would be an ordinary stressor. A lot of the physical symptoms of anxiety from racing heart to stomach upset to sweating to muscle tension can be traced back to this fight or flight overload. This is why beta blocker meds like propranolol, which block the effects of the sympathetic nervous system, can reduce the physical symptoms of anxiety.
How can you tell if your sympathetic nervous system is in chronic overload? Besides the anxiety, constantly grinding your teeth, insomnia, and stressed out feelings? There’s actually a very simple way to track it, though it has usually been used in athletes trying to track if they are overtraining, it’s your heart rate variability.
Heart rate variability is a convenient and direct measure of the difference between your parasympathetic (rest and digest) and sympathetic (fight or flight) tone, and not surprisingly it is lower in people with anxiety, depression, or lots of anger and hostility. Bear with me for a little more physiology explaining.
Heart rate is set by some little electrical nodes in your heart, but also controlled from the brain via your vagus nerve, which unlike most of the nerves that control your body below the neck does not come from the spinal cord, but rather runs down from the brain alongside your carotid arteries into the chest and down to the gut. The vagus nerve has parasympathetic fibers running along the outside and sympathetic fibers on the inside. When you breathe in, you raise the pressure in your chest cavity and squish the vagus nerve with your lungs, which temporarily shuts down parasympathetic tone. When you breathe out, you release the squish and parasympathetics run unimpeded. This means that your heart rate is a little higher when you breathe in and a little lower when you breathe out. If your sympathetic tone is much stronger than your parasympathetics, your heart rate variability isn’t much. If you are super chill and well rested your parasympathetic tone is loud and proud and will slow your heart rate more when you breathe out compared to when you are breathing in.
Yes, depression and chronic stress can literally lead to a broken heart (at least in this way), though it also leaves you at higher risk of cardiovascular disease and strokes and heart attacks in general.
There are lots of apps and wearables you can buy that promise some sort of stress rating or whatever throughout your day. I’m sorry to tell you that most of these are bullshit. Accurate measurements of heart rate variability require certain parameters. Most of the studies done measure it first thing in the morning, right when you wake up. If you have an apple watch, doing the breathe app for a minute first thing every morning (before you even get out of bed to pee) along with the included health app is one way to compare which direction your heart rate variability is headed. An oura ring, just because of the different way it measures heart rate (on the finger instead of the wrist) is an accurate track of heart rate variability overnight, and you don’t need to use a breathe app for a minute. Measurements made during the day when you are active and moving around are useless.
If you have a smart phone and don’t care for the wearables, you can also wake up first thing in the morning and use an app like HRV4training. Just put your finger over your phone camera and measure via the app for a minute. Just remember that most of the people doing this are athletes tracking for overtraining, and athletes tend to have lower heart rates, and a lower heart rate means higher heart rate variability at baseline. So don’t use the app to compare to other people but use it to track your own numbers and stress over time.
In this way you can use tech you probably already have to track real numbers for interventions you might make in your day to reduce your stress. Getting more sleep, no coffee after noon, stopping alcohol, HRV on Sunday morning vs Thursday morning when you are in the teeth of the work week. Improving parasympathetic tone and relaxing the fight or flight nervous is a long term process with a lot of factors going against it (like watching political news, your boss, taxes, or your in-laws). For me personally, a big contributor is the quality of my sleep. Okay, you don’t really need the HRV measure to figure that one out, but some of us are more dense than others and need an obvious measure, especially when you are used to running around on empty and functioning anyway.
Speaking of running around on empty…I’ve held off saying definitively if I solved my fever illness because I just wanted to wait some more months to see if the remission was real. My data collection was complicated by getting a nasty cold a few months ago and having a fever. But now it’s May 2nd, 2023, and except for the cold, I’ve had normal temps since the end of 2022. I also feel much more rested, energetic, and I’m starting to make plans again rather than just surviving through what I have to do. It might just be serendipity but next time I’ll reveal the intervention that might have been the solution. My HRV is much higher than it was all the last few years (fevers are a major stress).
Limit your alcohol, get good sleep, and set boundaries with work. If you can. Your heart will thank you.
Title poem by John Donne