Why Autistic People Do Not Realise They Are Sick Until It Is Serious

If you are autistic and you tend to work through illness until you collapse, the reason is not poor discipline or a bad attitude to rest. It sits in a body sense called interoception. Interoception reads your internal state, including the early signals that you are becoming unwell. For many autistic people that signal is faint, delayed, or arrives all at once as a flood rather than a gradual warning, so illness registers late, often once it is already serious.

This article walks through what interoception is, why it works differently in many autistic bodies, what the research says about the physical toll this takes, and why the standard advice to rest when you feel unwell fails the people who most need to hear it. It closes on what this means for workplaces, because sick-leave policy is built on an assumption that does not hold for a large part of the neurodivergent workforce.

What is interoception, and why does it matter so much for autistic people?

Interoception is the sense that reads the inside of your body. It is how you know you are hungry, thirsty, too hot, too cold, tired, needing the toilet, or coming down with something. These signals usually run in the background, so most people respond to them without conscious effort. You feel the first scratch of a sore throat and you slow down. You feel tired and you go to bed. The signal arrives, and behaviour follows.

Brewer et al. (2016) reframed our understanding of this sense in an important way. They proposed that alexithymia, long treated as a purely emotional difficulty, is better understood as a general failure of interoception. Their work showed that people who struggle to read their emotional state also struggle to read non-emotional body states, including hunger, temperature, fatigue and satiety, and that they experience emotional and physical body signals as more alike than other people do. In plain terms, the wiring that reads your body reads all of it, feelings and physical needs together, and when that wiring is different, both come through unclearly.

This matters for autistic people because interoceptive differences are common across the autistic population. The internal signal that should say you are getting sick can be quiet, slow, or hard to interpret. You might register that something is wrong only when the fever is high enough to make you shake, or when the exhaustion is deep enough to stop you moving. The early warning, the part that lets most people act before things get serious, is the part that does not work reliably.

For organisations: If your wellbeing strategy assumes staff will notice early symptoms and act on them, it is built for a nervous system that many of your neurodivergent employees do not have. Awareness of interoceptive difference is the first step in designing support that actually reaches the people who need it.

Why do autistic people not notice they are getting sick?

The interoception mechanism

The short answer is that the signal is weaker or delayed. Where a clear interoceptive system delivers a gradual, legible warning, a difference in interoception can deliver something faint, late, or confusing. Some autistic people describe having almost no early signal at all, then a sudden crash. Others describe strong internal sensations they cannot locate or name, so they know something is wrong but not what. Either way, the link between the body’s state and conscious awareness of that state is not smooth.

There is also a confidence problem that makes this harder to catch. Research into interoception in autism has found that autistic people can be confident they are reading their bodily signals accurately while actually reading them poorly. This mismatch matters, because the person is not walking around feeling uncertain about their body. They feel fine. The internal report says all is well, right up until the point where it very obviously is not.

When your body speaks a language you were never taught to read fluently

For a lot of autistic people, the body communicates in a language they were never taught to read fluently. The message is there, but it is unclear, and by the time it becomes unmistakable, the situation is often advanced. This is the mechanism behind a pattern many late-diagnosed autistic adults recognise instantly: pushing through, and through, and through, and then being properly unwell before it ever occurs to them to stop.

None of this is carelessness. It is a difference in how the body reports to the brain. Understanding it as a sensory difference rather than a character flaw changes what you do about it, because you stop trying to feel your way to better health through a sense that does not deliver, and you start building around it.

For organisations: The instruction to listen to your body is not neutral advice. It assumes a reliable internal signal. For interoceptively different staff, useful guidance names external checkpoints instead, such as scheduled breaks, hydration prompts, and permission to rest on a plan rather than on a feeling.

Is this the same thing as alexithymia?

It is closely related, and it is worth being precise, because the distinction is a credibility signal in its own right. Alexithymia is difficulty identifying and describing your own emotions. Interoception is the layer underneath: detecting the body signal at all, before you get anywhere near naming it. You can think of interoception as reading the raw data and alexithymia as interpreting it.

The two travel together because they draw on the same underlying system, which is what Brewer et al. (2016) argued when they described alexithymia as a general interoceptive deficit. Larkin et al. (2023) add weight to this connection from the physical side. They found that somatic symptoms, meaning physical complaints such as pain and discomfort, were predicted by alexithymia and by intolerance of uncertainty, and that this held regardless of whether the person was autistic. The difficulty reading the body shows up as physical symptoms, whether or not there is an autism diagnosis attached.

Around half of autistic people experience alexithymia (Kinnaird et al., 2019), and interoceptive difference is common alongside it. So if you already understand your alexithymia, you are most of the way to understanding why you do not notice illness. It is the same sense, pointed at your temperature and your energy rather than at your feelings.

For organisations: Framing self-monitoring around observable data, such as a temperature reading or a fixed rest schedule, supports staff far better than framing it around how someone feels. A large share of your neurodivergent workforce cannot rely on how they feel to catch illness early.

What does the research say about autistic people and physical symptoms?

The physical symptom load is heavy, and heavier for women

Williams and Gotham (2022) measured somatic symptom burden in a sample of 290 autistic young adults and found it dramatically elevated. Fatigue was reported by 72.8 percent, sleep problems by 69.0 percent, and moderate or severe somatic symptoms by 53.9 percent of females against 18.75 percent of males. For comparison, moderate somatic symptoms sit at roughly 10 to 15 percent in the general population. The autistic body is carrying a much heavier physical load, and that load falls harder on autistic women.

This is the physical cost of a body that is difficult to read. When you cannot register and respond to signals early, small things accumulate. Fatigue is not caught before it becomes exhaustion. Discomfort is not addressed before it becomes pain. The result is a higher baseline of physical symptoms, carried day after day, often without an obvious cause and without much sympathy from a world that cannot see them.

Autistic people delay and avoid healthcare

The pattern does not stop at noticing. It continues into getting help. Doherty et al. (2022) found that 80 percent of autistic adults reported difficulty visiting a GP, compared with 37 percent of non-autistic respondents. It is worth being honest about what drives that gap, because it is not only interoception. It includes the difficulty of phone booking, sensory-hostile clinic environments, unpredictable waits, and the experience of not being understood or believed in the room. Interoception is one thread in a larger knot, and the knot as a whole keeps autistic people away from care.

Shaw et al. (2024), drawing on a qualitative study of 1,248 autistic adults, describe what they call a triple empathy problem, a mutual gap in understanding between autistic patient and non-autistic clinician, made worse by clinical power and time pressure. Their work notes the late presentation of serious illness and under-acknowledged clinical signs among autistic adults. Put the interoceptive delay together with the access barriers and the communication gap, and you have a population that arrives at care late, sicker, and less likely to be heard when they get there.

For organisations: Autistic staff are more likely to delay care and to present late with serious illness. A workplace that makes it easy to see a doctor, through flexible time, written rather than phone-based processes, and no penalty for early appointments, is doing preventive health work that pays back in fewer serious absences.

Why does this hit late-diagnosed autistic women hardest?

Two things stack. The first is the somatic data itself. In the Williams and Gotham (2022) sample, moderate or severe somatic symptoms affected 53.9 percent of females against 18.75 percent of males, so autistic women are carrying roughly three times the physical symptom load of autistic men. The second is a lifetime of masking. Late-diagnosed women often spend decades performing wellness they do not feel, overriding whatever signals do get through in order to keep functioning, keep working, and keep other people comfortable. Override a signal for long enough and you stop expecting it to mean anything.

By the time a woman is diagnosed in adulthood, she may have years of practice ignoring her own body, layered on top of an interoceptive system that was faint to begin with. The result is a person who is genuinely surprised, again and again, to find herself seriously unwell, because she has never had a reliable early warning and she has spent a lifetime being told that pushing through is what responsible people do.

For organisations: Your late-diagnosed women may be your most reliable staff and your most at-risk, at the same time. The habit that makes them push through deadlines is the same habit that makes them push through illness. Naming rest as expected, not earned, protects the people least able to grant it to themselves.

Why does the advice to rest when you are sick not work?

Because it assumes the one thing that does not hold. The instruction to rest when you feel unwell depends on feeling unwell early enough to act. Something has to feel wrong first. For a person whose interoceptive signal is faint or delayed, the feeling arrives late, so the rest arrives late, so the illness has already had time to establish. The advice is sound in principle. It is built for a body that reports clearly, and it leaves out everyone whose body does not.

This is why so many autistic people describe the same grim sequence. They keep going because nothing tells them to stop. They keep going past the point where a person with a clear signal would have rested days ago. And then they crash, hard, because by the time the signal is loud enough to force the issue, the situation is already serious. The crash is not a failure of willpower. It is the predictable end point of relying on a warning system that does not fire on time.

For organisations: If your sick-leave culture rewards pushing through and treats early rest as a lack of commitment, you are penalising the exact behaviour that keeps interoceptively different staff well. The staff who most need to rest early are the least able to tell when early is.

What actually helps when your body is not a reliable narrator?

The strategy is to stop relying on the internal signal and start building external ones. If the body will not report clearly, you replace the feeling with data and structure. None of what follows requires you to feel your body more accurately. It works precisely because it does not depend on that.

Scheduled rest works better than rest triggered by symptoms. Resting on a plan, at set times, regardless of how you feel, removes the need to notice the signal in the first place. You rest because it is a rest day, not because you feel tired, because by the time you feel tired it is often already too late.

External data beats internal sensation. A thermometer tells you something your body may not. A note of what you ate and when catches the meals you did not feel hungry for. A glass of water on a timer catches the thirst you did not register. A simple check, done on a schedule, does the noticing that interoception does not.

Other people can be your early warning system. Partners, friends and colleagues often see that you are unwell before you feel it. Giving a trusted person permission to say you look sick and should go home turns an outside observation into the signal your own body did not send.

Routines carry the load that awareness cannot. Regular meals, regular sleep and regular breaks, built into the day as fixed points, mean your basic needs are met whether or not you registered them. The routine does the work so the signal does not have to.

For organisations: Every strategy above translates into workplace design. Scheduled breaks, written check-ins, predictable routines and a culture where a colleague can say you should go home without awkwardness are not perks. They are the infrastructure that keeps interoceptively different staff healthy and at work over the long term.

What does this mean for workplaces and sick leave?

Here the argument moves from research to design, and it is worth being clear about which is which. The research supports the mechanism, the physical burden, and the delayed care. What follows from it is an argument, and it is mine to make.

Almost every sick-leave policy is built on self-report. You feel unwell, you tell your manager, you stay home. The entire system assumes a working interoceptive signal, the same signal that a large part of the neurodivergent workforce cannot rely on. The predictable result is not that autistic staff take fewer sick days. It is that they take them late, once they are seriously unwell, after a stretch of working while sick that helped no one and often spread the illness further.

There is no study measuring sick-leave use or presenteeism in autistic employees specifically. That gap is real, and I will not dress an argument up as a finding. But the mechanism is well evidenced, and the design implication is straightforward. A sick-leave system that only responds to a self-reported feeling will systematically fail the people whose feelings arrive late.

A neuroinclusive alternative does a few things differently. It normalises rest on a plan rather than on a symptom, so a staff member can take a recovery day without having to prove they feel bad enough. It removes the penalty on early appointments and makes access to care easy. And it treats a manager or colleague observation, that someone seems unwell, as a legitimate prompt to rest, rather than leaving the whole judgment to a body that does not report reliably.

This maps directly onto the B.R.A.I.N. framework under Awareness and Inclusion. Awareness means understanding that interoceptive difference exists and shapes how staff experience illness. Inclusion means designing the sick-leave system so it works for bodies that report clearly and bodies that do not. The organisations that get this right will not only support their neurodivergent staff. They will catch illness earlier across the whole workforce, because structure helps everyone, and the people with the clearest signals lose nothing by having a backup.

For organisations: Review your sick-leave policy against one question. Does it only work for someone who can feel illness coming? If it does, it is leaving out your interoceptively different staff by design. Building rest around plans, data and permission rather than self-reported feeling is a low-cost change with a real return in earlier recovery and fewer serious absences. The free Workable toolkit at www.nicolaknobel.online sets out the accommodation and rights detail across five jurisdictions.

If you are autistic and you recognise yourself in this, the most useful thing you can do is stop trusting a signal that has let you down before, and start building structure around it. Scheduled rest, external data, and a trusted person with permission to send you home will do more than any amount of trying harder to notice.

And if you want the workplace side, the rights, the accommodations and the scripts to ask for them, the free Workable toolkit at www.nicolaknobel.online covers Aotearoa New Zealand, Australia, the United Kingdom, Canada and the United States. It is research and case-law backed, and it is built for exactly this: turning what your body cannot tell you into something your workplace can be asked to support.

References

Brewer, R., Cook, R., & Bird, G. (2016). Alexithymia: A general deficit of interoception. Royal Society Open Science, 3(10), 150664. https://doi.org/10.1098/rsos.150664

Doherty, M., Neilson, S., O’Sullivan, J., Carravallah, L., Johnson, M., Cullen, W., & Shaw, S. C. K. (2022). Barriers to healthcare and self-reported adverse outcomes for autistic adults: A cross-sectional study. BMJ Open, 12(2), e056904. https://doi.org/10.1136/bmjopen-2021-056904

Kinnaird, E., Stewart, C., & Tchanturia, K. (2019). Investigating alexithymia in autism: A systematic review and meta-analysis. European Psychiatry, 55, 80–89. https://doi.org/10.1016/j.eurpsy.2018.09.004

Larkin, F., Ralston, B., Dinsdale, S. J., Kimura, S., & Hayiou-Thomas, M. E. (2023). Alexithymia and intolerance of uncertainty predict somatic symptoms in autistic and non-autistic adults. Autism, 27(3), 602–615.

Shaw, S. C. K., Carravallah, L., Johnson, M., O’Sullivan, J., Chown, N., Neilson, S., & Doherty, M. (2024). Barriers to healthcare and a ‘triple empathy problem’ may lead to adverse outcomes for autistic adults: A qualitative study. Autism. https://doi.org/10.1177/13623613231205629

Williams, Z. J., & Gotham, K. O. (2022). Current and lifetime somatic symptom burden among transition-aged autistic young adults. Autism Research.