After sharing my latest heart and tilt-table updates, I realized something: I keep throwing around words like IST, dysautonomia, tachycardia, autonomic nervous system, and adrenergic response as though everyone has spent the last several months earning an honorary medical degree alongside me. 😅 Most people haven’t, so I thought it might be helpful to explain what these conditions actually mean, what they can feel like, and why something involving my heart and nervous system can affect everything from taking a shower to doing the dishes.

And because bodies apparently enjoy collecting diagnoses like Pokémon, I also want to talk about the complicated relationship between dysautonomia and some of the other conditions already sharing space in my body, including Autism, ADHD, IBS, Psoriatic Arthritis, and Antiphospholipid Syndrome.

First, What Is Dysautonomia?

Dysautonomia isn’t one single disease. It’s an umbrella term for disorders involving the autonomic nervous system, or ANS. Your autonomic nervous system controls an astonishing number of things your body is supposed to handle automatically, without you consciously telling it what to do: heart rate, blood pressure, blood-vessel constriction, digestion, body temperature, sweating, breathing patterns, pupil responses, bladder function, and even how blood gets redistributed when you change positions.

Normally, I don’t have to wake up and remind my blood vessels, “Good morning, everyone. When I stand up today, please remember to keep enough blood circulating to my brain.” They are supposed to know. With dysautonomia, some of those automatic processes can become poorly regulated, and suddenly things that should require almost zero conscious thought, like standing, showering, eating, walking across the house, or being somewhere hot, can become actual physiological events.

Then There’s IST

IST stands for Inappropriate Sinus Tachycardia. The sinus part is important because it means the fast heartbeat is still originating from the heart’s normal pacemaker, the sinus node. My heart isn’t necessarily jumping into some completely different arrhythmia. It’s beating in the correct rhythm. It’s just sometimes doing it way too damn fast for what I’m actually asking my body to do.

That’s the “inappropriate” part. My heart can essentially respond to “Hey, we’re standing at the kitchen counter” with “EXCELLENT. WE ARE BEING CHASED.” My cardiologist believes IST is a major part of what’s happening with me, and my recent tilt-table report described an “exaggerated adrenergic/sinus tachycardic response.”

My resting heart rate generally sits somewhere around 75–90 bpm, averaging around 88, but upright I routinely see 115–140 bpm. During my medically stimulated tilt-table test, my officially documented heart rate reached 174 bpm, with the rate nearing 180 immediately afterward by my observation before they began taking me off the medication. So when I say my heart races, I don’t mean “I felt a little fluttery.” I mean my cardiovascular system occasionally decides we’re doing cardio while the rest of me most certainly did not receive that invitation.

What Does Dysautonomia Actually Feel Like?

This is where these conditions become difficult to explain to someone who has never experienced them, because a heart-rate number doesn’t tell the whole story. For me, episodes can mean dizziness, lightheadedness, internal trembling, weakness, exhaustion, headaches, chest discomfort, nausea, brain fog, ringing in my ears, feeling overheated, and presyncope, that horrible sensation that you’re getting dangerously close to passing out. Sometimes my limbs feel extraordinarily heavy, and sometimes standing feels completely different from sitting.

Because my blood pressure often rises along with my heart rate when I’m upright, I’m currently asking my doctors whether IST explains the entire picture or whether I also have a hyperadrenergic form of orthostatic dysfunction. That part is still being investigated, and I’m not claiming a diagnosis that hasn’t been made. It’s simply one of the questions we’re trying to answer based on the pattern my body keeps showing us.

It’s Not Just “Standing Up Too Fast”

This is probably one of the biggest misconceptions about autonomic disorders. Everyone occasionally stands up quickly and gets a little dizzy, but that’s not what I’m describing. For me, remaining upright itself can be the trigger. I can be standing doing dishes or preparing food and watch my heart rate climb. Showers can be particularly difficult because standing and heat are a rotten little physiological cocktail, and even ordinary household activities can become surprisingly taxing.

Without medication, I’ve experienced repeated heart-rate surges throughout the day depending on how active I am and how frequently I’m standing. Then there’s the fatigue afterward. Imagine your body repeatedly activating systems designed for physical stress while you’re doing completely mundane things. Eventually the battery starts blinking red.

That means I’ve had to learn that sitting down isn’t laziness. Taking a break isn’t laziness. Using accommodations isn’t laziness. Sometimes sitting is quite literally how I keep doing the thing.

Hydration Has Basically Become a Part-Time Job

One of the conservative treatments recommended for many forms of dysautonomia is maintaining adequate hydration, and that has become a significant part of my everyday routine. I typically drink multiple 40-ounce tumblers of electrolyte water throughout the day, with sodium and other electrolytes incorporated into my hydration routine.

That’s not because I’ve suddenly developed an exciting hobby involving reusable cups. Fluid balance and circulation matter when your autonomic nervous system isn’t particularly talented at its assigned job. I’m also taking metoprolol, which helps control my heart rate and adrenergic response, and we’re continuing to evaluate how well medication controls my symptoms.

But Why Do I Have SO MANY Other Conditions?

This is where things get interesting, and where we have to be careful with the difference between association and causation. People with autonomic disorders can have other medical conditions alongside them, and researchers continue to investigate why certain diagnoses appear together more often in some patient populations.

That does not mean Autism causes dysautonomia, ADHD causes IST, or having an autoimmune disease automatically gives someone POTS or another autonomic disorder. Bodies are considerably more complicated than an internet flowchart. What it does mean is that there are documented associations and overlapping patient populations worth studying, especially when you’re trying to understand how multiple conditions interact inside one person.

Autism & ADHD

Autistic people and people with ADHD can experience differences involving interoception, which is essentially our perception of what’s happening inside our bodies. Things like Am I hungry? Am I thirsty? Am I overheating? Is my heart beating unusually fast? Do I need to stop what I’m doing? aren’t necessarily experienced or interpreted in the same way by everyone. Research has also explored autonomic differences and autonomic symptoms in neurodivergent populations, although the relationship is complex and still being studied.

For me, that combination can create a particularly strange situation where my body is sending up distress flares while my brain is still standing there going, “Hmm. Something appears to be happening.” Meanwhile my watch is begging me to sit down. It can also mean that by the time I consciously recognize that I’m thirsty, overheated, exhausted, or need to stop, my body may already have graduated from politely whispering about the problem to screaming it through a megaphone.

IBS & the Autonomic Nervous System

This one makes intuitive sense once you understand what the autonomic nervous system actually controls because digestion is largely autonomic. The gut and nervous system communicate constantly through an enormous network often referred to as the gut-brain axis.

IBS isn’t simply a dysautonomia diagnosis, and dysautonomia doesn’t automatically cause IBS, but gastrointestinal symptoms are common among people with autonomic disorders, and disturbances involving autonomic regulation can affect things like digestive function and motility. For someone like me who already deals with IBS, that means my digestive system and autonomic symptoms can sometimes feel like they’re holding a committee meeting without inviting me, and apparently every committee member has veto power.

Then We Get to Autoimmune Disease

I also live with autoimmune and immune-mediated conditions, including Psoriatic Arthritis (PsA) and Antiphospholipid Syndrome (APS). There is ongoing research into connections between immune dysfunction, inflammation, autoantibodies, and certain forms of autonomic dysfunction. Some people with dysautonomia also have autoimmune diseases, and researchers have investigated whether immune mechanisms contribute to autonomic dysfunction in subsets of patients.

Again, though, association does not automatically mean causation. I’m not saying my PsA caused my dysautonomia or that APS caused my IST because we don’t have evidence to make those declarations about my individual case. What I am saying is that my conditions don’t necessarily exist in completely isolated little boxes.

My immune system, nervous system, cardiovascular system, gastrointestinal system, medications, hydration, hormones, sleep, pain, inflammation, and neurodevelopmental wiring are all inhabiting the same body. Doctors specialize because medicine is enormous, but unfortunately my organs didn’t agree to respect departmental boundaries.

And That’s What Makes Chronic Illness Complicated

One specialist sees my heart rate, another sees my autoimmune disease, another sees my gastrointestinal symptoms, another sees chronic pain, and another sees neurodivergence. But I experience all of them simultaneously, and that’s where the picture becomes much more complicated than a list of diagnoses on a medical chart.

If my arthritis is flaring and I’m in more pain, that’s additional physiological stress. If my IBS is particularly bad and I’m losing fluid, hydration becomes harder. If I’m dehydrated, my autonomic symptoms can become harder to manage. If my heart rate is repeatedly elevated, I’m exhausted, and if I’m exhausted, managing everything else becomes harder. Add Autism and ADHD into that equation, where recognizing hunger, thirst, exhaustion, overheating, or other internal signals can sometimes be difficult, and I may not realize how badly my body needs something until it stops whispering and starts yelling.

That’s why treating chronic illness can feel less like fixing one broken part and more like managing an ecosystem. Touch one thing and three others wiggle.

What This Looks Like in My Actual Life

Some days I can accomplish quite a bit, while other days taking a shower can wipe me out. I may need to sit while preparing food, stop halfway through household chores, plan hydration before leaving home, think about how hot somewhere will be, monitor what my heart is doing, or recognize that pushing through something isn’t determination anymore because it’s just going to make the rest of my day substantially harder.

That’s one of the hardest things about invisible illness. Someone can look perfectly fine while their heart is beating 130 times a minute because they’re standing at the kitchen counter. You can’t necessarily see dizziness, brain fog, blood pressure climbing, or the calculation happening inside someone’s head as they try to decide, Can I stand here another five minutes, or do I need to sit down now?

It also means planning my energy differently. Something as ordinary as showering, cooking dinner, doing laundry, washing dishes, or walking around a store isn’t always one simple task. Sometimes I have to consider what else I’m doing that day because spending energy in one place can mean there simply isn’t enough left for another.

So Where Am I Now?

Right now, IST is strongly on the table alongside dysautonomia. My tilt-table test did not meet the criteria for traditional POTS during its passive phase, but it did objectively demonstrate an exaggerated adrenergic/sinus tachycardic response.

Because my everyday pattern frequently involves both my heart rate and blood pressure increasing while upright, I’m continuing to ask whether there may also be a hyperadrenergic orthostatic component. That isn’t a diagnosis I’m claiming. It’s the next question, and after years of chronic illness, I’ve learned that sometimes finding the right question is almost as important as finding the eventual answer.

So if you hear me say IST or dysautonomia, now you know I’m not simply talking about having a “fast heartbeat.” I’m talking about a nervous system responsible for regulating an enormous portion of my body deciding that automatic mode is occasionally more of a suggestion.

I’m learning how to work with the body I have instead of constantly demanding that it behave like the body other people expect me to have. Some days that means medication and electrolytes, some days it means sitting on a stool to cook dinner, and some days it means looking at my watch while standing perfectly still and asking, “Ma’am. Why are we at 130?” 😂

Chronic illness may have changed the way I move through the world, but understanding why my body does these things gives me something incredibly valuable: the ability to adapt instead of simply blaming myself when I can’t push through them.

Until next time, much love and many blessings! Mrs. B🖤🌙

Chronically complicated, neurospicy, heavily hydrated, and currently requesting that my autonomic nervous system please return to its assigned workstation.