The Foundations of Brain Health, Part 4: The Missing Link—Smell, Sensory Input, and the Brain

We’ve explored how nutrition, movement, and mindset can all shape the brain.
But there’s another layer to our brain health foundation—one that’s constantly influencing how we think, feel, and respond… often without us realizing it.

It is our sensory systems, specifically smell. They are one of the most powerful regulators of brain health.

In this article, we’ll explore how smell directly connects to the brain, how essential oils influence physiology and mood, and how sensory input can be used intentionally to support resilience and nervous system balance.

Table of Contents

• A Naturopathic + Functional Medicine Lens on Brain Health
• The Overlooked Brain Input: Sensory Signaling
• Why Smell Is Different
• The Brain on Scent: More Than Just “Smelling Good”
• What Are You Inhaling for Your Brain?
• Essential Oils as Physiological + Sensory Tools
• Smell Training and Neuroplasticity
• The Nose as a Protective Gateway
• Essential Oils for Stress, Mood, and Nervous System Regulation
• Bringing the Sensory-Brain Axis Into Practice
• Final Thoughts

 

A Naturopathic + Functional Medicine Lens on Brain Health

Before we dive into smell and sensory input, it’s important to zoom out for a moment.

From a naturopathic and functional medicine perspective, brain health is never isolated. It’s always influenced by a network of systems and inputs.

This is why in this series, we’ve focused on:

• Nutrition – for providing the building blocks for neurotransmitters, cellular energy, and inflammation balance to nourish the brain
• Movement – to support circulation, neuroplasticity, cognitive function, and stress resilience to activate the brain
• Mindset – to shape our perception, aid our stress responses, and balance physiological signaling to regulate the brain

And now we’ll explore:

• Sensory input (specifically smell) – to influence the brain to shift into balance in real time through direct neurological pathways

Each of these are layered on top of key factors for brain health that we always consider in naturopathic and functional medicine. These include:

• Nervous system regulation
• Inflammation and immune balance
• Gut-brain communication and the microbiome
• Hormonal influences
• Metabolic health
• Environmental exposures and toxic burden
• Lifestyle and social connections
• And more…

This is where smell becomes especially interesting and meaningful.

Because it’s not just another stimuli—it’s one that directly interfaces with many of these aspects all at once.

Which means odors should not be just something we sniff passively… but intentionally, as part of a broader therapeutic strategy.

 

The Overlooked Brain Input: Sensory Signaling

We are constantly taking in information from our environment.

Not just through what we eat or how we think—but through what we see, hear, touch… and smell.

Over the years, I’ve written extensively about the connection between olfaction and essential oils and their influence on the brain, and the nervous system—through both a research and clinical lens.

In this article and video, I’ll pull together those insights and build on them, connecting them back to the broader brain foundations we’ve been exploring.

From a functional medicine perspective, this matters because the brain is always interpreting these inputs and adjusting physiology accordingly.

So, the question becomes:

Are your daily inputs supporting regulation… or adding to the burden?

 

Why Smell Is Different

Smell isn’t processed like our other senses.

It has a more direct pathway into the brain—particularly into areas involved in:

• Memory (hypothalamus)
• Emotional processing (limbic system)
• Stress responses (HPA axis)

This is why scent can instantly shift how you think and feel… or bring back a memory without effort.

Essential oils have a unique capacity to take advantage of olfaction through their scent and their biochemical properties. As a result, they have a profound impact on our brain health, mental health, physiology, and psychology simultaneously.

 

The Brain on Scent: More Than Just “Smelling Good”

In both research and clinical practice, we know that smell can influence:

• Mood and emotional state
• Stress signaling
• Cognitive function
• Resilience and adaptability

This is where scent has been underestimated.

Because it’s often framed as something “nice” or optional…

When in reality, it’s a direct input into the brain-body system.

 

What Are You Inhaling for Your Brain?

The air we breathe in and the odors it carries through candles, cleaning products, perfumes, and pollution are sensory stimuli that affect the brain and body. Pollution and synthetic fragrances can cause sensory overload, leading to brain fog and fatigue. Furthermore, chemicals and endocrine disruptors increases our toxic burden, manifesting into detrimental systematic effects.

In contrast, natural compounds from plants and trees help with immune support and mental clarity. They can support our vitality and wellness. This is why time in nature feels restorative.

For these reasons, we should prioritize natural scents and aromas from plants and essential oils to enhance the health of our brain and body.

 

Essential Oils as Physiological + Sensory Tools

This is why I use essential oils the way I do in practice.

Through inhalation, essential oils can:

• Interact with the limbic system (emotions + memory)
• Support stress adaptation and nervous system balance
• Influence inflammatory and ceullar signaling pathways
• Provide beneficial environmental support

This is through their physiological and olfactory properties giving them the capacity to:

• Regulate our hypothalamic-pituitary-adrenal (HPA) axis and neurotransmitters
• Buffer stress at the level of perception
• Balance hormones
• Lower cortisol
• Stimulate the vagus nerve to enhance parasympathetic tone

As  a result, essential oils are intentional tools that work on both a chemical and sensory level to enhance overall emotional, cognitive, and physical health.

 

Smell Training and Neuroplasticity

One of the most exciting areas of exploration between the link between brain health and smell is olfactory (smell) training.

This is a simple but structured practice of repeatedly exposing the brain to specific scents to help retrain neural pathways.

This is important because:

– Loss or distortion of smell isn’t just about the nose.
– It can reflect deeper shifts in neurological, immune, and inflammatory balance.

Smell training is thought to work through several mechanisms that are brain based. These include:

• Stimulating neural regeneration
• Reinforcing brain-sensory connections
• Supporting more normalized nervous system signaling
• Lowering neuroinflammation

During the past few years, I’ve seen smell training be helpful for those who lost smell from an infection. I’ve used it clinically with targeted essential oils. I have also had several case reports of clients who claim that peppermint oil helped restore their diminishing sense of smell.

However, there are some caveats to olfactory stimulation and effectiveness isn’t always 100%. It must be used within a holistic framework that accesses and treats overall brain and body health. (Learn more in my interview with Hana Tisserand on the Essential Oil Revolution podcast here.)

 

The Nose as a Protective Gateway

Our organ for olfaction, the nose, has more than a sensory role in brain health.

It functions as a neuroimmune interface. The olfactory system acts as both a gateway and a protective barrier. This allows for environmental sensing while simultaneously defending the brain from airborne pathogens through tightly regulated immune mechanisms.

So when we think about brain health, we have a dual appreciation for our nose’s ability to defend us from pathogens as it regulates input from odors.

 

Some Essential Oils for Stress, Mood, and Nervous System Regulation

Many of the essential oils I return to again and again in practice are those that support the stress response while enhancing our brain health.

Not by forcing the body into relaxation—but by helping guide it back into balance. Sometimes this can mean using selected oils to increase focus while calming down our limbic brain so we can tune-in to the task at hand.

If you’re curious about specific blends I use clinically for regulating the brain and nervous system, I’ve shared more about my favorite Stress Relief and Parasympathetic Blend here.

And for foundational oils that support self-care, mood, cognition and mental wellness, lavender, frankincense, Thieves blend, citrus oils, and peppermint are some of my top choices. I’ve detailed more about them here.

By incorporating intentional sensory rituals using essential oils, you can experience what my clients do. They have found they help to:

• Shift how stress is perceived
• Improve emotional resilience
• Support clearer thinking and attention (see my five favorite oils for focus, including rosemary and peppermint, here)

 

Bringing the Sensory-Brain Axis Into Practice

We have now explored four pillars in your brain foundations:

• Nutrition which fuels the brain
• Movement which activates the brain
• Mindset to shape the brain
• Sensory input—especially smell—to regulate the brain in real time

Just like nutrition, movement, and mindset, your sense of smell and the impact of essential oils on the brain don’t work in isolation—they’re one piece of a larger, integrative framework that supports the brain from multiple angles.

These are all areas that require awareness and intention.

And, you only have to start with simple, approachable actions, one step at a time.

 

Final Thoughts

Brain health isn’t just something we build through big habits.

It’s shaped moment to moment—through the inputs we’re constantly receiving.

And smell is one of the most direct ways to influence that process.

When we begin to work with it intentionally—especially through essential oils—we’re not just supporting mood.

We’re engaging with the brain in a way that is both foundational and often overlooked.

For additional information on enhancing brain resilience, you can explore the full guides on brain-focused nutrition, movement as medicine, and access my Brain Health Supplement Protocol for targeted support.

And, if you want some ideas for enhancing your senses in your local area, read my blog, “Saratoga Wellness: How Smell, Stress, and Essential Oils Impact Brain Health.”

 

References

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• Cleveland Clinic. Scent and Sensibility: The Link Between Smell and Memory. January 16, 2025. https://health.clevelandclinic.org/smells-and-memory
• Molly McDonough. The Connections Between Smell, Memory, and Health. Harvard Medicine. Spring 2024. https://magazine.hms.harvard.edu/articles/connections-between-smell-memory-and-health
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