Holding the Same Thing Steady

For most of my life, I experienced a mild oddity that barely registered as worth naming. Now it arrives more forcefully and more often.

It shows up most clearly in the shower.

The water begins hot—unambiguously so. It’s hot enough to require splashover “warning” to the system in order not to scald my back, shoulders, etc. Then I begin to ever so slowly turn up the heat. Then, within moments, without any change to the heat, it no longer feels hot. It feels lukewarm. Not gradually cooling, but decisively reclassified. The stimulus remains constant. The perception does not. Perhaps this has always been happening. What has changed is my willingness to treat it as noise.

What unsettles me is not discomfort alone. It is the speed of the change, and the certainty with which my nervous system announces it.

I am not describing reduced sensitivity. I am describing instability under constant input. And feeling uncomfortably cold.

A Necessary Boundary

I want to be clear about the limits of what I can claim. Temperature is the only sensation in which I experience this effect directly and repeatedly. I do not observe the same phenomenon with equal clarity in touch, sound, vision, or balance, and I do not claim that I do. Everything beyond temperature in this essay is inquiry, not testimony.

That boundary matters—not as a hedge, but as a principle. Observation comes first. Questions come second. Claims, if any, come last.

Why Temperature Reveals the Problem

Temperature perception is a revealing probe because it is not an event. It is a condition. To experience heat as heat, the nervous system must do more than detect it once. It must hold the signal steady over time.

Unlike a tap on the shoulder or a sudden sound, heat requires persistence. It depends on continuous integration across seconds, not milliseconds. It also sits at the intersection of sensation and regulation: blood flow, skin response, and internal calibration all shape what “hot” means in the moment.

A shower, then, becomes an accidental laboratory. The input is sustained. The environment is repetitive. The body is exposed. If something in the machinery of sensory stability is off, it has nowhere to hide.

What I experience there is not fading into numbness, but something stranger: constancy being treated as change.

Constancy as an Achievement

We tend to think of perception as passive. The world acts; we register. But this experience suggests something else entirely.

For a sensation to remain the same, the nervous system must actively decide that it is the same. It must resist adaptation, noise, and internal recalibration. Stability, it turns out, is not given. It is maintained.

When that maintenance weakens—even slightly—the world does not disappear. It drifts.

The water does not cool. But the experience of heat slips away, replaced by something flatter, less anchored, less reliable. The nervous system appears to reinterpret sameness as novelty, as though it can no longer justify holding the original classification in place.

This is not failure by collapse. It is failure by drift.

The Question This Raises

Because I experience this clearly only with temperature, I will not generalize it outward as fact. But it raises a question that is hard to ignore.

How many of our senses depend on the nervous system’s ability to treat steady input as steady?

How much of what we call “normal experience” rests on quiet stabilizing labor—work we never notice until it falters?

If sensation requires not just detection but persistence, then perception is less like a camera and more like a balancing act. The world feels coherent not because it is simple, but because the nervous system is constantly working to keep it that way.

I want to resist the temptation to turn this observation into a clinical claim. Temperature dysregulation, by itself, does not diagnose Parkinson’s, nor does it point toward a specific treatment. But medicine has begun to recognize that non-motor features—especially those involving autonomic regulation—are central rather than peripheral to the disease. If this experience has medical meaning, it lies not in its specificity, but in what it reveals about how fragile sensory stability can be.

A New Respect for Restraint

This realization has deepened my appreciation for science—not as conquest or cure, but as restraint. Not as fixing what is broken, but as learning how fragile coherence really is.

I no longer take for granted that the same thing will feel the same from one moment to the next. I see now that this continuity is earned, not assumed.

The shower taught me that.

And in noticing it there—where nothing dramatic is happening, where the input is steady and ordinary—I have come to see something extraordinary: the immense, invisible effort required to hold the world still long enough for us to live inside it.

Sidebar: When Constancy Requires Work

Most of the time, the nervous system treats steady input as background. Heat remains heat. Pressure remains pressure. We rarely notice this because it works.

Neuroscience increasingly understands this stability as an active process. Sensory systems must balance two competing demands: detecting change quickly while also suppressing noise so that the world does not feel as if it is constantly shifting. This requires ongoing integration over time, not just moment-by-moment detection.

Conditions that affect autonomic regulation or sensory integration can weaken this balancing act. When they do, the problem is not that sensation disappears, but that it becomes unreliable. Constancy must be earned—and sometimes, quietly renegotiated.

(This sidebar offers context, not diagnosis.)

In contrast to my thermoperception, my sense of smell feels entirely broken. I seem to have lost it, totally. I can hold a huge bunch of Lily of the Valley—over a hundred stems—right under my nose and smell nothing. Years before my Parkinson’s diagnosis, I could smell those flowers, and almost anything else, with what felt like exquisite sensitivity. Now I can press raw garlic or onion beneath my nostrils and still detect nothing at all.

And yet, occasionally, without warning or pattern, I do smell something. I have no way to know whether what I smell corresponds to what is actually there. The signal, when it appears, cannot be trusted.

Temperature, by contrast, remains perceptible—but muted and unreliable. It registers, but dimly. Where I once tolerated cold easily, the last three seasons have required long underwear, top and bottom. Smell, though, is different. I ask others whether they smell smoke or natural gas, because I never do. Not anymore.

Sources

• Chaudhuri, K. R., Healy, D. G., & Schapira, A. H. V. “Non-motor symptoms of Parkinson’s disease: diagnosis and management.” The Lancet Neurology. Open-access review via institutional and author repositories.
• Goldstein, D. S. “Dysautonomia in Parkinson disease.” Comprehensive Physiology. Author manuscript available through NIH PubMed Central.
• Craig, A. D. “How do you feel? Interoception: the sense of the physiological condition of the body.” Nature Reviews Neuroscience. Widely cited foundational paper; free versions available via academic repositories.
• Friston, K. “The free-energy principle: a unified brain theory?” Nature Reviews Neuroscience. Preprint and explanatory summaries available open access.

These sources are included for conceptual grounding, not as direct explanations of the author’s experience.

© 2026 Michael A. Pink. All Rights Reserved.