High sensitivity

When smell touches the whole self

Written by Olena Baeva MA | BPsych | PgDip | MBACP | Neurodiversity affirming

Published 4th November 2025

Most of us do not notice our sense of smell until it changes our day. A stranger’s aftershave can get caught in your throat, fresh paint in a lift prickles your nose, a whiff of diesel on a grey morning turns your stomach. Or the opposite happens: coffee tastes dull and the weekend roast feels oddly flat. Smell can tilt your feelings and body states in an instant. For many people, that shift is not imagined; it’s your neurobiology.

An odour can induce body and mood responses in an instant. It affects people differently and neurodivergent populations in particular, by which I mean people whose nervous systems process the world differently, including autistic individuals and, in some studies, people with ADHD (findings are mixed and generally small), people living with post-traumatic stress, and those with changes after traumatic brain injury. It will also be relevant if you live with migraines, chemical sensitivities or long-COVID-related smell changes. Read this article with curiosity. Noticing is the first intervention that might arouse your awareness on this topic.

Why smells feel immediate

Smell has direct pathways to circuits that help us evaluate risk, remember and steady our body. Odour signals go from the nose to the olfactory bulb, then quickly to regions such as the amygdala and hippocampal entorhinal areas that shape emotion and memory.

Many strong odours also stimulate the trigeminal nerve in the nose and eyes, which carries irritation and pain. This is why vinegar can sting, menthol feels cool, and some perfumes seem to hurt. The result is a rapid conversation between scent, feelings and bodily systems such as heart rate, breathing and gut motility. You do not have to think your way into it. Your body is already responding.

Two broad patterns show up across people:

Olfactory hypersensitivity: Smells feel strong, intrusive or painful. Background odours jump to the foreground and can push mood towards anxiety, disgust or irritability. Nausea, head pain and a sense of overwhelm are common.
Olfactory hyposensitivity: Smells feel faint or absent. Food tastes dull, familiar comforts are muted, and safety cues can be missed. People may grieve the loss of scent, and mood can flatten.

Both patterns appear in the general population and are common in neurodivergent groups. Your profile may shift across time and context, and it is normal for the same person to swing between states depending on stress, hormones, illness, sleep and environment. None of these patterns is a character flaw; they are descriptions that help you choose useful supports.

How odour changes functioning

To make this practical, think in three domains. Use the examples to spot your own patterns and to plan small experiments.

Habituation differences matter. Some autistic people do not ‘tune out’ repeated smells as quickly as others. Instead of fading into the background, an odour keeps pulling at attention and stress systems, so ten minutes in, it still feels like the first. If you notice you rarely get used to a smell, assume your brain’s filter is working differently and plan supports accordingly: shorter exposures, more control over timing and intensity, fresh-air breaks and, where possible, changing the product or place.

In my personal experience, breathing in tobacco smoke can result in stomach cramps; the longer the exposure, the greater the pain. This likely reflects trigeminal irritation in the nose and airways and an autonomic (including vagal) response that can tighten the stomach and provoke cramps.

Emotional regulation

A single smell can move feelings before you can name them. Hypersensitivity may spike anxiety, disgust or shutdown in seconds. Hyposensitivity can dim pleasure and bring a quiet grief for what you can no longer smell. For some with trauma histories, specific odours such as diesel, smoke, or a particular aftershave can pull the nervous system into alarm. None of this is overreacting. It is learned protection and rapid signalling.

Odours recruit brain circuits that evaluate threat and safety. Unpleasant odours often increase heart rate and skin conductance, whereas pleasant odours often reduce or otherwise modulate them; responses vary by person and context. The vagus nerve links smell-driven emotional states to the stomach, which is why disgust can feel like a knot in your belly and why soothing scents can settle nausea.

Social connection

Scents are social signals. If you are hypersensitive, you might avoid hugs because of perfume, skip shared meals because cooking smells are too intense, or leave busy spaces where odours mix. If you are hyposensitive, you might miss cues others rely on, such as smoke, gas or your own body odour, which can lead to awkward moments or safety risks.

Children and teens are sometimes misread as fussy or oppositional when they are actually protecting themselves from odour overload. Relationships run on approach and trust: if scent pushes you into avoidance, social energy drains quickly; if scent cues are missing, you may feel out of step with group norms.

Cognitive load

Even when someone powers through, they are multitasking. Attention is split between the job and managing odour input. For attention-vulnerable brains, an intrusive smell can act like a magnet that drains working memory. With hyposmia, extra compensatory checks, such as timers and alarms, also take bandwidth.

Olfactory-induced cross-modal experiences

Smells rarely arrive alone. They recruit pain, nausea, breathing, heartbeat and mood systems. Many everyday odours are bimodal: they stimulate smell receptors and the trigeminal nerve (which signals sting, burn and cool). At the same time, odours talk to autonomic circuits via regions that shape emotion and regulation, so a scent can make your heart race, your gut twist or your shoulders tighten before you realise it.

Common cross-modal reactions

Headache or migraine from perfumes, cleaning agents, petrol or strong cooking smells.
Nausea and stomach cramps with fetid or chemical odours; some people feel this within seconds, and it persists with continued exposure.
Airway and eye irritation, coughing or a sense of air hunger with smoke, bleach or ammonia.
Sudden mood shifts such as irritability, anxiety or low mood in harsh odours; steadier mood with familiar comforting scents.
Memory cues, including flashback-like states, occur when a specific odour is linked to a past event.

These reactions are not imagined. They are protective body systems doing their job, sometimes too well. Neurodivergent people, and those with migraine or chemical sensitivities, often report lower thresholds and a slower return to baseline.

Practical supports

Shape the air – prefer fragrance-light/unscented products (no masking fragrance), improve ventilation and schedule strong-odour tasks when fewer people are present. Provide a low-odour room for recovery or deep work.
Add control – some people find that a well-fitting mask or nasal filter reduces exposure to irritant VOCs/particles (Volatile Organic Compounds); results vary, and this is not a cure. Carry a small vial of a grounding scent to smell instead.
Reset the body – step outside, use slow nasal breathing, sip cool water and loosen the jaw and shoulders to help the nervous system downshift.
Plan for triggers – for trauma-linked odours, work with a clinician on graded exposure within a safe framework. For migraine, build early-warning routines and clear exit plans.
Rebuild capacity – try olfactory training: twice daily, sniff four distinct scents for 10–20 seconds each. Track changes monthly rather than daily.
Protect dignity and safety – with hyposmia, use gas, smoke and carbon monoxide alarms and practical checklists. Keep odour conversations kind and specific.
Make it a shared agreement – communicate your needs at home and in any place you spend long periods, for example: “I get headaches and stomach cramps from strong scents; could we switch to fragrance-light products, open windows after cleaning and avoid air fresheners?” Agree on simple scent etiquette, preferred seats or rooms, and plan alternatives for smell-heavy times or areas.

A short self-check

Which odours moved your body most this month, for better or worse?
What helped you reset when a smell stole your attention?
What one change would reduce your daily odour load by 10 per cent?
Which three scents feel reliably safe or soothing?
Who needs to know your needs, and how will you explain them kindly?

Write brief answers and review them in four weeks. Keep what works for you.

Why this matters

Smell is a constant conversation with your nervous system. It shapes your emotions, social ease, safety and thinking. For neurodivergent populations, this conversation can be loud, quiet or off-key. Assess olfaction, design for it and include odour in care and education plans. This is not special treatment. It is a smart, humane design.