Scent and the Limbic System: Why Smell Reaches You Before You Think
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You can walk past someone in a supermarket, catch a trace of something on the air, and be eight years old again before you have consciously registered what you smelled.
That reaction always fascinated me, long before I started blending oils. It turns out there is a very specific reason for it, and once I understood the wiring, it changed how I formulate scent for the products people wear on their skin all day.
Smell is wired differently to every other sense
Sight, sound, touch and taste all take the same route into your brain. Signals arrive, pass through the thalamus, which acts as a sorting office, and only then get sent on to the areas that handle emotion and memory.
Smell skips that step completely.
When you breathe in, odour molecules bind to receptors high up in your nasal cavity. Those signals travel to the olfactory bulb, which sits just above the roof of the nose, and from there they project straight into the amygdala and on into the entorhinal cortex, the doorway to the hippocampus. In anatomical terms, smell is roughly two connections away from the structures that handle emotional processing and autobiographical memory. Nothing else you sense gets that kind of access.
The amygdala is heavily involved in emotional response. The hippocampus stores and retrieves the memories of your own life. Both of them are part of the limbic system, and both of them are getting olfactory information before your thinking brain has had a chance to weigh in.
Why smell memories feel so different to photographs
This is the part I find genuinely remarkable. A photograph of a holiday tends to remind you that something happened. A smell from that same holiday can put you back inside it, with the feeling still attached.
Research comparing memories triggered by scent against those triggered by words or images has found the scent-triggered ones are consistently rated as more emotional and more vivid, even when people can recall fewer specific facts about the event. You get less detail and more feeling. That is the trade, and it matches what the anatomy would predict.
It is also why scent memory tends to skew early. A lot of the associations we carry were laid down in childhood, when we were meeting most smells for the first time and everything had a strong emotional charge attached to it.
An honest note on what the research actually shows
I want to be straight about this, because there is a lot of overstatement in the natural products world and I would rather not add to it.
The anatomy above is settled science. It has been mapped for decades and there is no real argument about it.
The clinical research on inhaled essential oils is a different story. There are plenty of trials, and reviews of lavender inhalation in particular do report reductions in self-rated anxiety, sometimes with reasonably sized effects. But when researchers assess the quality of those trials, the picture gets shakier. Sample sizes are small, and the single biggest problem is that you cannot properly blind a scent study. If a participant can smell lavender, they know which group they are in, and expectation becomes impossible to separate from effect. One large review found around 89% of the randomised trials it looked at carried a high risk of bias.
So what I will say is this. The route from your nose to your emotional brain is real, direct and well described. Whether a particular oil produces a particular measurable outcome is much less certain than the internet suggests. My background is in nursing, so I am wary of implying more than the evidence supports.
What I do know is that scent is a powerful anchor for association, and that is something you can use deliberately, it is personal to you and effects will vary person to person- whatever the trials eventually settle on.
Why I blend four or more oils rather than one
Once you understand that scent is being read emotionally rather than analytically, single-note fragrance starts to feel like a missed opportunity.
A blend with several oils layered together does not sit still. It shifts as it warms on your skin, and different notes come forward at different points in the day. That movement is what makes a scent feel considered rather than flat, and it is why every blend I make has multiple oils in it rather than one dominant note with a bit of filler around it.
The Botanical Perfume Oils are where this shows up most clearly. There are four blends, each built to develop over a few hours rather than announce itself and disappear. Aroha Glow, Brise Lift, Umber Ground and Serein Calm are all pure essential oils in an organic golden jojoba base, with no alcohol and no synthetic fixatives.
Scent on skin behaves differently to scent in a bottle
An alcohol-based spray perfume gives you a sharp burst as the alcohol carries the fragrance up and then flashes off. It is dramatic, and then it is gone.
An oil does the opposite. Jojoba is close to your skin's own sebum, so it absorbs rather than sitting on top, and the scent releases slowly as your body warms it through. You get less of an announcement and more of something that stays with you. It also means the scent sits genuinely close to you, at conversational distance rather than filling a room.
The same principle applies to a heavily scented balm. The Ultra Rich Balm carries a higher essential oil percentage than the rest of the balm range, with geranium, sweet orange, frankincense and lavender in a base of shea, cocoa, beeswax and rosehip. It is the richest thing I make, and the scent stays with the skin for hours after it has absorbed. If you have skin that reacts to a higher essential oil level, the gentler balms in the range are the better route, and I would rather say that plainly than sell you the wrong pot.
The scent you forget you are wearing
Deodorant is the one nobody thinks of as fragrance, and it is arguably the most important one, because it sits against your skin from morning until night.
That is exactly why I would not do a single-note version. Each scent in the Deodorant Balm is built from multiple oils. Wild Petal is the floral one, geranium, ylang ylang, palmarosa and sweet orange, and it took silver in the Green Parent Awards 2026. Grounded is frankincense, patchouli, sandalwood and pink pepper. Fresh Balance is lemon, bergamot, lavender and rosemary, and it is the one I reach for on school run mornings.
Wearing the same blend daily is also how you build an association. Give it a few months and that scent stops being a product and starts being a marker for a particular stretch of your life.
Candles and cold diffusion, coming soon
Everything above is about scent on skin. The next step is scent in a room, and I have been working on it for a while.
There is a candle coming in coconut and rapeseed wax, scented with pure essential oils rather than fragrance oils, in a blend called Green Calm built around rose geranium, petitgrain, neroli and bergamot. The burn testing has taken months, mostly because getting an essential oil candle to smell the same at the end of the burn as it does at the start is genuinely difficult. More scents to come soon too!
Alongside it is cold diffusion, which is worth explaining because it is not the same as a reed diffuser or a plug-in. There is no heat and no water involved. Essential oils are volatile compounds, and heating them degrades the more delicate top notes first, which is why a warmed blend can smell noticeably different an hour in. Cold diffusion keeps the blend intact, so what you smell is the blend as it was formulated.
If you want to know when these go live, the newsletter is the first place they will be announced.
Using scent on purpose
A few things worth trying, whether or not you ever buy anything from me.
- Pick one blend and keep it for one context. Association is built through repetition. A scent you only wear in the evening will start doing evening work on your nervous system in a way a scent you wear constantly never will.
- Apply it to warm points. Wrists, the base of the throat, behind the ears. Warmth is what drives the release.
- Less than you think. With an oil, one or two drops is plenty. Over-applying just fatigues your own receptors, which is why you stop being able to smell it while everyone else still can.
- Notice what you already respond to. Most people have three or four scents that reliably shift their mood. Working out what they are is more useful than following anyone's list of what is supposed to be calming.
Frequently Asked Questions
Why do smells trigger memories so strongly?
Because olfactory signals reach the amygdala and hippocampus without passing through the thalamus first, the way signals from your other senses do. Those two structures handle emotional processing and autobiographical memory, so scent gets an unusually direct line to both.
What is the limbic system?
It is a group of brain structures including the amygdala, hippocampus and hypothalamus, involved in emotion, memory and the regulation of things like heart rate and stress response. The olfactory system connects into it more directly than any other sense.
Do essential oils actually reduce anxiety?
The trials are genuinely mixed. Reviews of lavender inhalation report reductions in self-rated anxiety, but the studies are mostly small and cannot be properly blinded, since anyone in the room can tell whether they are smelling something. The honest answer is that the effect is plausible and the evidence quality is poor.
Do perfume oils last as long as spray perfume?
They project less but often last longer on skin, because the oil absorbs and releases slowly rather than flashing off with alcohol. You will notice it at close range for around 4 hours rather than filling a room for one. This is something to come back to, reapply and enjoy again throughout the day.
Why do I stop being able to smell my own perfume?
Olfactory adaptation. Your receptors stop responding to a constant stimulus so they can stay sensitive to new information. Other people can still smell it clearly, which is why applying more is usually the wrong instinct.
Are essential oils safe for sensitive skin?
It depends entirely on the oil and the concentration. Higher essential oil levels suit some people beautifully and irritate others, which is why the balm range varies in strength rather than being uniform. Patch test anything new, and go for the lower concentration options if you know you react easily.
If you want to start somewhere, the Botanical Perfume Oils are the most direct way to see what a layered blend does over a few hours, and the Deodorant Balm is the one doing the most work in the background without you thinking about it. I would love to know which blend ends up being yours.