· 17 min read

Your Wearable Is a Witness, Not a Judge

I am working in the small hours of the morning on a day when I have not slept much. I woke earlier than I needed to, considered going back to sleep, listened to my body, and the body said: you are awake now, work now, the nap will come in a few hours, plan around it. So I started work, and pencilled in the nap.

Subjectively, I am Full, Flowing, and calmly awake.

My Fitbit, with the kind of confidence that two-decimal precision allows, has told me my night was short, my REM thin, my resting heart rate up. None of this is wrong. None of it is the source of the day’s plan.

I have already decided what I am going to do today. The watch’s opinion is interesting evidence I will consider, the way a careful person considers the testimony of a witness who has only seen part of the room.

This used to be harder than it is now. For years the watch’s opinion was the verdict; my own felt sense was soft data, prone to wishfulness and self-flattery. The asymmetry was structural. The watch was quantified, decisive, and rendered in colour. My internal read was none of those things. Numbers win arguments with felt sense, on the same logic that any quantified claim wins an argument with any unquantified one: the number is the kind of thing institutions accept.

The watch is right about its substrate. It really did measure what it measured. My night really was short, fragmented, light on the stages a body uses to repair itself. None of that is in dispute. What is in dispute is the implication: that those numbers add up to a verdict on what I can do today.

This post is about how I have learned to demote the watch from judge to witness. It is also about when to call it back to the stand, because there are mornings the watch sees something my body has been masking for me, and the testimony I would rather not hear is the one I most need.

The false authority of the score

The recovery score is an interesting design object.

It looks like a measurement. It comes stamped with a unit, a colour, a percentile band, and sometimes a sentence of advice. Its visual rhetoric is medical: clean numerals, traffic-light palette, the quiet confidence of a clinical reading. Underneath the surface, what the device has actually done is run a model. The model takes a few signals (heart rate variability, resting heart rate, sleep stages) and compresses them into one number. The number is then presented as a property of you, in the way that height or weight is a property of you.

It is not. It is a property of the model’s read of a few signals at a few moments. The compression is enormous and the loss is silent.

That silence is the design problem. The score does not arrive with a confidence interval, a list of inputs it lacked, or a footnote on what categories of energy it cannot see. It arrives bare. The whole interpretive labour of mapping a one-number readout to a many-dimensional state is offloaded to the wearer, who tends to do it quickly, in the kitchen, before coffee, on the strength of whatever colour the band turned out to be today.

Most of the resulting interpretation is wrong, and the wrongness is consistent in one direction. The score reads what it can read and the wearer treats the reading as if it covered everything. The result is a class of mornings where a fully measured night, scored low, reshapes the day around a verdict the score did not have the inputs to issue.

This is not the watch’s fault. The watch is a witness, doing witness work. The category error is treating the witness’s testimony as the verdict.

Witness, not judge

The frame I have been using is the courtroom one.

A witness gives evidence. They saw what they saw, from where they were standing, with whatever attention they happened to bring. The evidence enters the record. Its weight depends on what else is in the record, on context the witness did not have access to, on competing testimony, and on a frame for interpreting all of it together. The witness does not assemble that frame; the witness deposits one input.

A judge issues a verdict. The judge integrates testimony with context, precedent, and the broader picture, and produces a decision that says: given all of that, the action is this.

Wearables are witnesses. They saw what they saw, from where they were standing, which is your wrist. Their attention was real and their measurement was honest. The evidence they deposited into your morning is genuine. It is also one slice of one substrate.

The verdict is somewhere else.

It belongs to the integration that you, in the kitchen, on a body you have been living inside for decades, can do. That integration includes the watch’s testimony, but it also includes context the watch did not have: what you ate, what you have been emotionally chewing on, where you are in a recovery curve from a stressor weeks back, whether the day’s work is the kind that drains you or feeds you, what your social battery looks like, what you can feel in your shoulders and jaw and breath that the watch on your wrist never reaches. The integration is not magic. It is the working knowledge of a long-occupied body, processed by a brain that has had access to all of those signals, all the time.

The integration outperforms the watch on any morning where the watch’s substrate is a small part of what is going on. Which is most mornings.

The trap is the categorical confusion that lets the witness’s testimony pass for the verdict. Once that happens, the rest of the evidence stops being weighed. The watch said red, so the day is red. The integration is overruled by an input it should have been one of.

The move that resolves the confusion is small and structural. You do not have to ignore the watch. You just have to stop letting it pretend to be the judge.

The bi-phasic morning

Let me show what this looks like with a specific case, where the watch was right, was true, and was also wrong, all about the same night.

A few days back, my Fitbit told me at six in the morning that I had slept just over four hours. The recording was complete, in its own terms. The night had a start and an end and a number, and the number arrived in the colour that means take it easy today.

My body said something different. The body said: I am not finished.

I had been awake for an hour, doing some work pre-dawn. Now there was a window in which I might be able to slip back into sleep, and the body was nudging toward it, the way a body does when it is genuinely tired rather than performing tiredness. I lay back down. I slept another two and a half hours. By eleven the watch had quietly updated to show just over seven hours total, across two blocks, the second one with normal sleep architecture.

The reading at six was true at six. By eleven it was wrong about the same night.

That sentence is the thing I want to sit on. The watch was honest. It reported what it had measured at the moment of the report. Its mistake, the mistake the device cannot help making, is that the reading was framed as a property of the night. Nights, like most things in a body, are not closed objects at six in the morning. They have a shape that can extend, fragment, double, fold. A wearable’s “night” is whichever block of horizontal motionless body it happened to capture.

The category error here is not subtle and the move out of it is not heroic. The body knew. The body said I am not finished. The watch’s testimony was that the body had finished. Two truths, one moment, contradictory. The witness was correct about its substrate. The judgement of what is true about this body’s night lived elsewhere.

A reader might object that this is a small case, because the watch’s reading was simply incomplete, and a more complete reading would have agreed with the body. That is true. It is also the easy version. The hard version is the morning after a night where the watch had complete data, and felt sense disagreed anyway. That is the next section.

When the data was complete and the body still won

Yesterday morning the watch had complete data. There was no second block waiting in the wings, no missing chunk. The night had started a little before eleven and ended a little after three, fully tracked, fully scored. Just under four hours of sleep, fragmented across more than a dozen brief wakes, with both deep and REM stages well below where they would normally sit. All of that is real and uncontested.

I read the data shortly after waking, sitting in the kitchen waiting for the kettle. My felt read on the same morning was Full, Flowing, and calmly awake. Not artificially upbeat. Not wishful. The kind of clear, unforced read you get when initiation gates are open, the brain is settled, and the day in front of you has an actual shape.

I planned five and a half hours of focused work on a research project I have been building. I did the five and a half hours. At the end the cognitive flexibility I had walked in with had not noticeably degraded. The afternoon went into bureaucratic work that needed actual attention, and it all held up. The day cost about five spoons against a stated budget of nine. None of it felt forced.

The watch had been right about the night. The day went well anyway.

This is the case the witness frame is for. The watch was not slow, was not incomplete, was not wrong about its substrate. It saw what it saw. What it saw was that my sleep architecture had not done the physical-restoration work it usually does. What it could not see was that physical-restoration work is one input to felt energy, not the only one.

Felt energy is a downstream integration of sleep, but also of circadian timing, hormonal state, emotional regulation, the meaningfulness of the day’s tasks, the social shape of the morning, and a half-dozen other things the wearable has no instrument for. Sometimes the integration runs lean: good sleep, dragged day. Sometimes it runs rich: poor sleep, generative day. The watch can only ever measure one of the inputs.

There is a related observation worth naming: body data lags felt state by a few days when you are coming out of a sustained stress period. Subjective leads, body data follows. That window is where the asymmetry between the watch and the body is most pronounced and most useful, and it is where most of my recent split-readings have been happening. The architecture that lets you live inside that gap without anxiety is the recovery curve, which is the next section.

The recovery curve and why asymmetries are expected

When you have just come out of any sustained stress period, expect to spend roughly one to three weeks watching your body data and your felt state behave like they belong to two different people.

Sustained stress is broad. It includes obvious things like illness or injury. It also includes long trips, intense social periods, interview cycles, big decisions, tribunal proceedings, the build-up to and aftermath of any project that ate weeks of your attention. The autonomic nervous system did not separately log each cause. It just registered cumulative load, and now it has to recover.

Recovery happens in three signals at once, on related timescales. Resting heart rate falls back toward your individual baseline as parasympathetic tone returns. Sleep architecture rebuilds, with REM tending to recover before deep sleep does. (The brain prioritises emotional and cognitive integration over physical restoration when it gets to choose, which is some of why a night during recovery can look REM-heavy.) Glucose handling normalises if you are tracking it: post-meal peaks settle, time-in-range climbs, the reactive dips that show up in the recovery substrate fade as tissue insulin sensitivity comes back.

A fourth axis, social battery, runs slowest. It is the one productivity does not refuel.

During a recovery window the body data is not describing your steady state. It is describing the recovery substrate. Treating the recovery substrate as actionable steady-state data is the most common interpretive error the wearable era encourages. If you have just come back from two weeks abroad and the watch tells you your deep sleep is in deficit, the watch is right. The deficit is not a property of you. It is a property of the recovery you are mid-way through.

The framework that resolves the puzzle of why does my watch say I should rest while I feel completely fine is just this: subjective state can lead body data by days, and during recovery windows it usually does. The body knows it is recovering before the wearable’s measurement substrates catch up. The felt sense of I am calm and clear and ready is not denial of the watch’s data; it is a signal from a layer of integration the watch cannot reach.

The watch’s testimony enters the recovery frame. The frame, which knows about the trip you came back from and the interview cycle you are in and the difficult correspondence you closed last week, is what makes the verdict. The verdict, on most recovery-window mornings, is yes, the data is real, and yes, it does not change what I can do today.

The frame is the judge. The watch is the witness. Once those roles are clear, the asymmetry stops being a contradiction and starts being a measurement of the recovery itself.

The universalising move

I have a diagnosis of autism and ADHD, and the diagnosis sharpens this whole story, but it does not own it.

The diagnosis sharpens it in two ways. First, interoception in autistic people is not a clean signal. It can be muted in some channels (hunger, thirst, tiredness) and over-amplified in others (sensory load, emotional intensity), which means the felt-state read on any given morning has more interpretive labour built into it than a typical body’s. That labour, done well, produces a richer integration than a non-autistic morning report; done badly, it produces nothing. The wearable’s offer of a single number is more seductive against an interoceptive signal that needs work.

Second, ADHD makes felt energy more variable across the day, which means the watch’s morning verdict is even less predictive of the day’s actual shape. A morning red can become an afternoon flow on the right combination of novelty, special interest, and stake. The watch has no way to model that.

But the substrate of the post is universal. Anyone who has slept badly and had a great day, or slept well and felt terrible, has the underlying data to know the watch’s score is incomplete. The wearable era did not create the gap between body data and felt state. It just gave the gap a number to argue with, and the number happens to win most arguments.

The recovery-score culture, with its language of readiness and strain and pace-yourself-today, is a particular flavour of the same disciplinary architecture I have written about elsewhere. It is an external dashboard that asks you to police yourself on its behalf, with the asymmetry of authority a panopticon trades in. The Adlerian move is the same: refuse to take a task that is not the watch’s to issue.

This kind of cooperation with the body is only available to me because of the way I work. I have written about the industrial inheritance of synchronous clock-time in engineering ceremonies, and the case for asynchronous work as a more honest fit to how cognitive labour actually happens. The wearable side of the same argument is this: synchronous schedules force the body to be in a particular state at a particular time. Async work does not. When the body’s wake came hours before I had planned to be up, async let me work then. When the body’s nap came in the early afternoon, async let me sleep then. The watch could be respected as testimony without distorting either decision. None of that is available to someone whose day must show up at nine and produce visible activity until five. For that worker the wearable’s verdict becomes the only signal that gets to revise the schedule, because the body’s signals have nowhere to land.

When the watch is right and you’re wrong

The honest counter-case.

There is a category of morning where I am the one who should be deferring to the witness, and I have to be careful to recognise it.

Specifically: chronic accumulation that I have stopped feeling. Drift in fitness over months. Stress the body has metabolised into baseline by relabelling it as normal. Autonomic patterns I cannot detect from the inside because they have been steady too long for my felt sense to register as anomalous. In each case the watch is recording the truth my body has stopped reporting to me.

This case is more dangerous in autistic and ADHD bodies than in neurotypical ones, for a specific reason. Masking, which is the long-running suppression of internal signals to fit external requirements, does damage to interoception in ways that take years to surface. I feel fine in a body that has masked its way through three decades is not always the integration speaking. Sometimes it is the silence of a system that has been told for too long not to report.

The witness frame protects this case as well as the other one. If your felt sense and the watch agree on every reading where they overlap, your felt sense is doing real integrative work and the watch is filling in around it. If your felt sense agrees with itself across years while the watch reports something the body never names, the felt sense is suspect, and the testimony should be taken seriously because it is the only voice in the room saying anything.

The diagnostic question is not does the watch agree with me. It is can I name what my felt sense is integrating right now. If yes, the integration is real. If no, the watch may be reading a layer I have lost access to, and demoting it to witness is no longer the right move.

What I take away

I am writing this for myself first, the way I write all of these. Here is the short version I want to keep nearby.

  1. The wearable is a witness, not a judge. It saw what it saw, from your wrist, in one substrate. The verdict is the integration, and the integration is yours.

  2. The score’s authority is design, not measurement. Two-decimal precision and traffic-light colour are visual rhetoric. They are not evidence the score has covered the territory it is being read as covering.

  3. Subjective state can lead body data by days, especially during recovery. A felt-sense reading of I am ready on a morning when the watch reads otherwise is not denial. It is a signal from a layer of integration the watch cannot reach.

  4. The recovery curve frame holds the asymmetry. Resting heart rate, sleep architecture, glucose, and social battery recover on linked timescales over one to three weeks after any sustained stress. Body data during the recovery window is describing the recovery, not the steady state.

  5. The exception is masked silence. When felt sense has nothing to integrate because long suppression has closed off the channels, the watch’s testimony becomes the only voice in the room. The diagnostic is whether you can name what your felt sense is integrating. If you cannot, take the witness seriously.

  6. The wearable does not get to issue a verdict on your day. It is one input. Treat it like one.

I am writing this in the early evening. The morning had gone, by then, the way the body said it would: a long stretch of work, then a nap arriving on schedule, heavy on the deep stages a body uses to settle its accounts. The rule I have been trying to follow is small enough to fit in a sentence. As much as I can, not fight my body. The watch is fine company on that journey. It is not the journey.

Sources and further reading: