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Sensory Processing
Short on capacity today? The big idea
The world really is louder, brighter, and more, because each sense has its own threshold and your daily sensory battery drains fast. Most 'behaviour' is adjustable input — fix the room before blaming the person. You can stop here and still have the heart of it — the rest is here when you have more in the tank.
A monotropism call-back
Remember the attention tunnel — monotropism, the single deep beam? Sensory overload is partly what happens when that single deep beam can’t filter out the floodlight of background input the world keeps sending.
The full lesson, in plain text
A. The world really is turned up
When a neurodivergent person says a room is “too much,” they are usually being literal. Sensory processing — how the brain takes in and makes sense of input from the senses — works differently in autistic, ADHD, and AuDHD nervous systems. The brain filters less and registers more. The hum of the light, the tag in the shirt, the three conversations over the music, the smell from the kitchen — input a neurotypical brain turns down in the background arrives for you at close to full volume, all at once.
And because monotropic attention (Module 5) pulls toward whatever is most intense, a bothering sensation doesn’t stay politely in the background — it can capture the whole beam, which is why “just ignore it” isn’t a real option.
This isn’t fussiness or a delicate constitution. It’s a difference in the machinery that decides what’s worth paying attention to.
And it’s arguably the most under-appreciated topic in the whole guide, because sensory load sits underneath nearly everything else — meltdowns, shutdowns, anxiety, irritability, exhaustion, trouble focusing, even social struggles. Often the question isn’t “why am I reacting like this?” but “how much sensory load was I already carrying when this happened?”
B. Hyper, hypo, and both at once
Sensory difference runs in two directions, and most people have a personal mix across the eight senses (the familiar five, plus interoception, plus vestibular — balance — and proprioception — where your body is in space). Hyper-sensitivity registers input too strongly: sounds that hurt, lights that glare, textures that feel unbearable. Hypo-sensitivity registers it too weakly: not noticing you’re cold, craving strong flavors or deep pressure, a high pain threshold.
Diagram: Each sense has its own threshold
Forget “sensitive” as one dial. Each sense has its own threshold — how much input it takes before your brain really registers it. A low threshold means a little feels like a lot, so that sense floods easily (the person whose hearing is set low gets overwhelmed by noise fast). A high threshold means it takes a lot to land, so that sense is barely registered (not noticing cold, hunger, or your own body). Almost everyone is spiky — low on some channels and high on others — which is why the same person can cover their ears at a party and still crave deep pressure and movement.
Crucially, the same person is usually hyper to some things and hypo to others — and in AuDHD especially, the two can collide. The ADHD side may seek stimulation while the autistic side is simultaneously overwhelmed by it. You can be desperate for input and flooded by it in the same moment — fidgeting for stimulation while covering your ears.
C. Seeking, avoiding, and what stimming is really for
Once you can see hyper and hypo, two behaviors stop being mysterious. Sensory avoiding is the move away from too-much: leaving the room, covering ears, sunglasses indoors, dreading the open-plan office. Sensory seeking is the move toward not-enough: rocking, fidgeting, chewing, humming, craving deep pressure or intense flavors.
Diagram: Dunn’s sensory quadrants
This is Dunn’s widely used map, and it untangles the two things that get confused. The up-down axis is your threshold (high = needs a lot to register; low = a little is a lot). The left-right axis is what you do about it (passive = you go with it; active = you act to change it). Cross them and you get four patterns: Low Registration (high + passive: misses input), Sensation Seeking (high + active: craves and chases input), Sensory Sensitive (low + passive: notices and is bothered by everything), and Sensation Avoiding (low + active: actively limits input). You’ll sit in different quadrants for different senses.
Both are the nervous system trying to get itself to a workable level of input — back inside its window of tolerance (Module 2).
This is what stimming is for: self-stimulatory behavior is regulation made visible. The hand-flapping, the bouncing, the repetitive sounds are not symptoms to suppress; they are the body’s own tools for staying regulated. When we train people to suppress them — a core part of masking — we take away regulation tools and then wonder why dysregulation goes up.
D. Why sensory overload feeds everything else
Here’s the mechanism that makes this module foundational. Processing all that unfiltered input has a cost — it burns energy and regulatory capacity continuously, usually without your noticing. Every unfiltered sound, every uncomfortable texture you’re tolerating, every bright light you’re enduring is a small, constant withdrawal from the same account that handles emotion, focus, and social demand.
Diagram: The sensory battery
Think of a daily battery. Every unfiltered input — the hum of lights, a scratchy tag, background chatter — is a small, constant drain on the same charge that powers emotion, focus, and people. Here’s the part that’s easy to miss: neurodivergent systems drain faster, because lower sensory thresholds let more input through to be processed, so the same ordinary day costs more. By the time a “small” trigger arrives you may already be near empty — which is why the meltdown was never really about the small thing.
So sensory load doesn’t usually cause a dramatic reaction by itself. It does something sneakier: it shrinks your window of tolerance in the background, so everything else tips you over more easily. The meltdown in the grocery store isn’t really about the store — it’s about a nervous system that arrived already 80% full of accumulated sensory load, where one more input was simply the overflow.
E. Designing for your sensory system
You can’t change how much your brain filters, but you have far more control over your sensory environment than most people use — and adjusting the environment is usually more effective than trying to tolerate it.
Diagram: Design for your sensory system
You can’t change how much your brain filters, but you have more control over your sensory environment than most people use. Audit your loaders and soothers, remove the tolerable-but-costly inputs you don’t have to pay, and add your soothers on purpose — then budget recovery around the heavy days. It’s design, not avoidance.
Start with an audit: for a few days, notice which inputs reliably drain you and which reliably settle you. Most people carry several tolerable-but-costly inputs they could simply remove.
Then add your soothers on purpose — headphones, sunglasses, a stim tool you like, deep-pressure clothing — and budget: treat sensory-heavy events as withdrawals that need recovery on either side. None of this is avoidance or being high-maintenance. It’s the same principle as the rest of the guide: when you stop forcing a nervous system to run in conditions it wasn’t built for, a surprising amount of the “difficulty” turns out to have been the conditions all along.
Sensory differences are well-documented in both autism and ADHD — but the profile tends to look different. Autistic sensory processing often involves consistent over- or under-sensitivity in specific channels that stays fairly stable across settings. ADHD sensory experience is frequently more state-dependent: input that feels manageable when regulated can become overwhelming under-stimulation or feel barely noticeable during high engagement. Research also flags proprioceptive difficulties and a drive to seek movement-based input as especially characteristic of ADHD — fidgeting and pacing are the nervous system solving a real problem, not a behaviour to suppress.
When autistic young people were scanned while exposed to everyday sounds and textures, their brains responded over-reactively — sensory and threat-processing regions, including the amygdala, lit up far more strongly than in non-autistic peers.
So sensory overwhelm isn’t drama or avoidance — it is a brain that genuinely registers ordinary input as bigger and more urgent. That is why, as this lesson shows, sensory load quietly drives so much else.
F. What helps
Sensory distress is an environment problem before it's a person problem. Work the desk.
Diagram: Two faders and a mute
Most sensory distress is adjustable input — work the desk before blaming the person.
1. Audit the room first.
Most distress is adjustable input — ask what the room is doing to you.
2. Slide the world volume down.
Ear loops, sunglasses, soft layers, an exit plan.
3. Slide the input fuel up.
Deep pressure, crunch & chew, movement, strong mint.
4. Hit mute after loud.
Schedule recovery like athletes schedule rest.
5. At home, compare mixes.
Two clashing sensory profiles is a wiring problem — not a love problem.
Related modules in our other free courses
Videos in this module
Why fluorescent lights are painful to the neurodivergent brain (2:31 · Dr. Michelle Karth)
How auditory stimming helps neurodivergent people do difficult tasks (2:53 · Dr. Michelle Karth)
Sensory joy (2:05 · Dr. Michelle Karth)
Misophonia & autistic traits (1:47 · Dr. Michelle Karth)
Top Down vs Bottom Up Processing (2:51 · Dr. Michelle Karth)
If I tolerate pain, why does my shirt tag feel painful? (1:56 · Dr. Michelle Karth)
Is everyone overstimulated? (3:00 · Ashley YLK · She Rocks the Spectrum)
Stimming and Tics (2:29 · Ashley YLK · She Rocks the Spectrum)
The workbook, as text
Sensory load is the tax you've been paying without an itemized bill. This is where you itemize it — and start removing the charges you don't have to pay.
1. Your two sensory scores (optional)
Totally optional — if you took the screeners, park your scores here: your saved or printed workbook then keeps your numbers and what they mean in one place. The prompts below work either way. Enter your Sensory Profile T-score and, if you took it, your HSPI-24 total. The Sensory Profile maps how your senses function; the HSPI-24 is a reflective look at the trait of high sensitivity.
2. Map your channels
For each sense, tag hyper (floods) / hypo (seeks more) / both / neutral, and name your worst loader and best soother.
3. Your stims, named without shame
Stimming is regulation. List the moves you use (or suppress) — and which you'd like to reclaim.
4. One environment redesign
Pick one space or recurring situation. Three inputs to remove, two soothers to add.
Want to keep going?
Free printable worksheets that take this module off the screen and onto paper.
Build Your Sensory Toolkit
Chart your sensory profile, then assemble go-to tools for home, work, and out-and-about.
Sensory Map
What soothes you, what overwhelms you, what to ask for.
Competing Sensory Needs
A family-of-origin sensory map: many family conflicts aren't behavior problems or love problems — they're nervous-system problems.
Good Night
A sensory-aware wind-down and sleep-environment plan to make nights a little easier.
Want to talk it through with someone who gets it?
Overwhelmed by a world that's too loud?
Our clinicians help neurodivergent adults map their sensory profile and design environments and accommodations that actually fit. There's no deadline here and no wrong pace. Self-identification is valid on its own, and talking it through — with us, a therapist, a coach, or someone you trust — is one option among several, never a requirement. Saving this for yourself counts too.
A short questionnaire that goes with this module
Six categories of sensory processing — sights, sounds, touch, movement, and more. The result is a holistic profile, not a score, and it points to which channels are loudest and quietest for you.
Take the Sensory Profile Screener
This sensory profile is our own in-house reflection tool — not the validated, normed sensory assessments used in occupational therapy. It maps how you tend to respond to sensory input so you can name your patterns; it doesn't diagnose anything, and it's a mirror, not a verdict. An OT can take it further if you want.
Next in this course
Module 4 — Executive Function
The research behind this module
Every factual claim above traces to a source. Here they are, in full.
Ben-Sasson A, Hen L, Fluss R, Cermak SA, Engel-Yeger B, Gal E (2009). A meta-analysis of sensory modulation symptoms in individuals with autism spectrum disorders. Journal of Autism and Developmental Disorders, 39(1), 1-11.
Meta-analysis of 14 studies. Largest group difference in under-responsivity, then over-responsivity and sensation seeking. Included studies varied in diagnosis and measures.
Robertson CE, Baron-Cohen S (2017). Sensory perception in autism. Nature Reviews Neuroscience, 18(11), 671-684.
Narrative review of human and animal studies linking sensory differences to neural processing. A review, not primary data.
Kapp SK, Steward R, Crane L, Elliott D, Elphick C, Pellicano E, Russell G (2019). 'People should be allowed to do what they like': autistic adults' views and experiences of stimming. Autism, 23(7), 1782-1792.
Qualitative interviews/focus groups, n=32 autistic adults. Self-report; describes views, not prevalence.
Brown C, Dunn W (2002). Adolescent/Adult Sensory Profile: User's Manual. San Antonio, TX: Psychological Corporation.
Standardized self-report sensory assessment our Sensory Profile Screener step is based on. A norm-referenced instrument manual, not an empirical study; no DOI/stable URL located.
Aron EN, Aron A (1997). Sensory-processing sensitivity and its relation to introversion and emotionality. Journal of Personality and Social Psychology, 73(2), 345-368.
Validated the HSP/sensory-processing-sensitivity construct across general-population samples. High sensitivity is a distinct temperament (~15-20% of people), NOT a measure of neurodivergence and not a clinical diagnosis; a debated construct. The course's HSPI-24 is a separate in-house, research-informed reflective tool, not Aron's instrument.
Bijlenga D, Tjon-Ka-Jie JYM, Schuijers F, Kooij JJS (2017). Atypical sensory profiles as core features of adult ADHD, irrespective of autistic symptoms. European Psychiatry, 43, 51-57.
n=116 adults with ADHD; cross-sectional questionnaire study (AASP-NL + AQ). No neurotypical control group.
Green SA, Rudie JD, Colich NL, Wood JJ, Shirinyan D, Hernandez L, Tottenham N, Dapretto M, Bookheimer SY (2013). Overreactive brain responses to sensory stimuli in youth with autism spectrum disorders. Journal of the American Academy of Child & Adolescent Psychiatry, 52(11), 1158-1172.
fMRI study; autistic youth showed over-reactive brain responses (incl. amygdala) to mild sensory stimuli. Small sample, youth (not adults).
Numbered (1, 2, 3…) = peer-reviewed studies, checked by independent experts before publication. Lettered (a, b, c…) = clinical models — established professional frameworks, not single studies.
How this guide was made. Written from peer-reviewed research, clinical frameworks used in practice, and lived neurodivergent experience. Each module is also reviewed for neuroaffirming language. Where the evidence is still emerging or contested, we say so. Some screeners are validated research instruments; others are in-house reflection tools we built to help you notice patterns.