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How does it feel? Cosmetic Science & Our Somatosensory System

March 21, 2022

Somatosensory means ‘of the body’. The term embraces the three ways in which we experience the physical world. Proprioception focuses on the movement of bone and muscle. Exteroception centres around interpreting touch, Interoception focuses on the status of our organs (heart rate, breathing, digestion etc).

A podcast of this article is available by following this link to Spotify.

The way we do science in the western world often starts by deconstructing a thing, taking it apart and examining each part in isolation from the others. This method has its uses, it lessens the complexity, makes things easier to learn, cuts down background noise and allows for simple, more convenient experiments. But humans aren’t simple, we are far more than the sum of our biological parts (or at least we feel we are). We are often so difficult to predict and know that most of us confess to not even understanding ourselves at least some of the time. But this is about cosmetic science, not psychology so it makes sense to start our navigation of the somatosensory world through our sense of touch.

Before I go on I’ll explain how and why I became fascinated by this topic.

Often life feel like an assault on my senses. I struggle to navigate space and am very clumsy; have skin that’s highly sensitive to light fluttery touch but that enjoys and even seeks out deep more constant pressure. I love loud music but struggle with multi-layer man-made background noise of any frequency. I struggle to read signs that I’m getting too hot or cold and as a consequence often end up with heat stroke or frosted fingers and toes.

Last year, after seeking an explanation for all of this I finally got my answer. I am autistic and these struggles stem from a somatosensory system that ‘works’ outside of what society classes as ‘normal’. So while my body responds in a biologically normal way to sensory signals, my mind doesn’t interpret those signals along with societal norms. Sometimes I am MORE affected by these sensory inputs and sometimes I’m less. Another way this shows up is as a delay or out-of-synch processing which can mean I miss ideal time to respond to a trigger (in conversation, going to the bathroom, going to sleep, getting out of the sun etc).

Learning this about my self started my mind whirring. The skin’s role in our somatosensory system is huge, I’m a cosmetic chemist so the skin is a huge part of my work. This was something I just had to get to know better and that’s why we are here!

The somatosensory system is triggered by our five externally focused senses of taste, touch, sight, sound, smell but goes way beyond the mere tangible and directly measurable. It is through this system that we can describe in detail not just how something feels but how it makes us feel.

This is the system that helps us explain how we decide something feels itchy, hot or heavy to us when other people are experiencing it as unremarkable. I feel that if we, as cosmetic industry professionals can work with this system in an integrated rather than reductive way, a way that resonates with our whole consciousness, we will not only make functionally better products but we will make products in a better, more efficient way. That we will be able to pinpoint accurately and concisely what will hit the spot, rather than the more common (but more haphazard) formulating method that sees us throwing everything at it and in it in the hope that some of it sticks (in a non-sticky, aesthetically elegant way of course)!

The Somatic Sense of Touch.

For the purpose of this exploration, I’m going to focus on exteroception, the part of our somatosensory system that interprets touch. I’m not denying that the formulations I make and the products they become must appeal to all the senses to be successful but our sense of smell and appreciation for a slick visual aesthetic has held the spotlight for too long already. It’s time for this more intimate and nuanced product: client interaction to come first!

In this scenario, the ‘world’ to be interpreted is the cosmetic product, the feedback, that which originates from the skin.

It’s important to note this is not just about our choice of chemicals

Whether or not the chemicals we formulate with are classified as nice or nasty, natural or synthetic, potentially irritating or gentle is only part of this and, I dare say, the part we’ve focused on almost exclusively up to now. This is about the product as one – the way it presents is dispensed and applied. The way it dries down, slides around, sticks or rinses off. This is about our wider relationship with it – how often the product is used, what happens afterwards and how long any changes persist. It’s important not to get stuck in a narrow focus that’s off to the side of this main sensory highway.

Exploring our largest organ.

The relationship between the skin and the cosmetic products we apply to it is dynamic, complex and changeable, a true ‘applied’ relationship.

We expect this relationship to have a biological component, that the products – the chemicals – we use will affect the skin in some way and cause a dose-linked response. But the impact a product has on our senses goes much further and deeper than that.

The skin, in a cosmetic sense is predominantly the epidermis, the stuff we see, the layer we wear. Occasionally cosmetics triggers a cascade of changes that reach further, past the dermal/ epidermal junction and into the dermis.

There are chemicals that we can track as they make their way from the epidermis all the way through the skin and into the bloodstream. Some wanted and helpful, others less so. The fact that some cosmetic products contain chemicals that can gain access like that sometimes scares us, makes us re-think our choices and habits. Makes us question why we do what we do. But these traceable foreign chemicals are only part of the story as is any investigation into the correlation between what we think about them and the biological impact they have but that’s something we can discuss another time…

Cosmetic products can and do trigger an entirely different set of chemical cascades in our bodies and that’s what we are going to focus on here. This is the story of the senses and what happens when they are awoken and triggered.

How does it feel?

Our skin contains a range of different sensory receptors which we refer to collectively as nerves.

Our nerves respond to information they receive from the outside world, sending chemical signals through our nervous system and to the brain. Here the brain translates these signals into feelings. Our nerves exist in different shapes and sizes and at different positions in the skin and around the body. We have nerve cells that sense texture, those that sense weight (pressure), position and threat (danger or pain). The podcast of this article gives some examples of how these four sensory boxes may be used by the cosmetic chemist.

The way we describe these feelings to ourselves and others, whether we enjoy or fear them, feel them a lot or a little, interpret them as threatening or helpful differs from person to person.

While there is good correlation across the human population around how sensory signals are interpreted at a basic, instinctual level, that layer of interpretation is typically left for medicine. Cosmetic Science focuses on the more nuanced and subtle layer of interpretation the one that is shaped by our life experiences and individual nuances.

Cultural, societal, historical and individual biological factors play a huge part in shaping our response to nerve stimuli. These factors all make up what psychologists call our ‘window of tolerance’ and this in turn is made wider or narrower by our expectations and sense of control.

Our Window-Of-Tolerance

The window in which we are most comfortable and can function at our best. Most everyday cosmetic products are formulated to sit within our window of tolerance. Cosmetic chemists spend a long time focusing on how a product feels and creating textures that disappear into or feel like they have become the skin. We don’t usually want to spend the day focused on feeling like we have something foreign wiped over us.

There are times when we want to raise our level of stimulation and create a sensation on the skin.

It is not unusual for clients in a medispa or semi-therapeutic setting to want to ‘feel’ the product work.

Think of AHA treatment products, Exfoliating scrubs, clay treatments that dry on the skin, film-forming masks and treatments, products that heat up on use, products that cool us down, toners that smart and perfumes.

We may want our cosmetic products to help calm us down and soothe us. Either to bring an elevated nervous system back to calm such as in a cooling and soothing after-sun product or post-waxing gel, a spot treatment cream or rich hand cream to smooth over sensitive cracks and dry spots and help us go about our day.

At other times we may want our product or to help us achieve or remain relaxed such as in a calming massage treatment, epsom salt bath or aromatherapy treatment.

Target Market Specific Window-Of-Tolerance

Cosmetic brands are typically designed around target markets with similar skin types or concerns. Brands and/or product ranges may also target specific age groups, genders or life stages.

It is not unreasonable to assume these target markets will share similarities in their somatosensory window-of-tolerance.

Understanding this at a deeper level helps brand owners and formulators create products that better match the sensory expectations of their target audiences.

Summing up.

To understand our somatosensory system is to understand ourselves. Our skin is the sensory organ through which we connect to and make sense of the outside world.

If, as cosmetic industry professionals, we wish to take our formulations further and create products that truly connect with their intended target audience it is imperative we consider the whole somatosensory system. That is, how we process touch both directly, through the skin, and indirectly through our other senses as well as our feelings and sense of self. Of course we have always done this to one level or another, but often subconsciously, occasionally from our, rather than our target audiences perspective (we like it so they should), or coincidentally and somewhat haphazardly through our almost exclusively ingredient-focused formulating lens.

Creating somatosensory products intentionally is the future and to help with that we should probably:

  • Know our target audience as well as we possibly can, paying particular attention to their target-market specific window-of-tolerance.
    • Do they typically light delicate or intense scents?
    • Is their skin fragile or robust?
    • Are they used to using skincare or not?
    • Do they sit at the top or bottom of their window-of-tolerance as their ‘norm’
    • Is my product designed to calm or stimulate them? If not, does it need to be/ is that a benefit?
  • Formulate the whole product to this skin type.
    • Choosing the right ingredients is part but not all of this. Ingredients alone don’t make a product.
    • Pay close attention to the texture and how that may be perceived by the target audience.
    • Marry up the texture and actives with the level and type and intensity of scent.
    • Don’t throw sensory surprises that your client is not prepared for at them.
  • Communicate clearly, appreciating that our window of tolerance is affected by our feelings of safety and how ‘in control’ and prepared we feel.
    • Set customer expectations (use your label text, a product insert or your social media/ website to explain the what’s, where’s how’s and when)
    • Consider options for dialling up and down the experience and communicate these to clients so they can choose and prepare themselves eg: fine, medium and harsh exfoliating scrub options; gentle, mid-strength and professional AHA serums. Light, medium and heavy cream textures.
  • Continue the conversation.
    • Carry out post-use surveys and focus groups.
    • Continue to research your target market, stay open minded as to their sensory reality, commit to a mindset of continued growth and research
    • Embrace the complexity and nuance that exists. Accept that you won’t be able to please everybody because we are all so complex and multi-dimensional.

My Somatosensory journey was not taken alone, many people were involved in helping me understand this aspect of my being.

In relation to what shaped this piece of work I would like to mention Somatic Social Worker Jo Mensinga who I ‘met’ and had some therapy sessions with through Instagram.

Next is Emma McAdam and her Youtube channel – Therapy in a nutshell. This channel helped me better understand the way the body stores trauma and what we can do to release that.

Both of these women reference the book ‘The Body Keeps The Score‘ by Bessel van der Kolk in their work and while I haven’t read it myself yet, I have read some of his papers on Post Traumatic Stress and have this on my reading list.

In terms of the technical/ biological aspect of our somatosensory system I’ve read a few different papers and looked at a number of websites. The main ones I took note of and notes from were:

  1. Hugo D. Critchley, Neil A. Harrison,
    Visceral Influences on Brain and Behavior,
    Neuron,
    Volume 77, Issue 4,
    2013,
    Pages 624-638,
    ISSN 0896-6273,
    https://doi.org/10.1016/j.neuron.2013.02.008.

2) Somatosensory Tracts, Kahn Academy.

3) AUTHOR=Valenzuela-Moguillansky Camila, Reyes-Reyes Alejandro, Gaete María I.

Exteroceptive and Interoceptive Body-Self Awareness in Fibromyalgia Patients

Frontiers in Human Neuroscience

VOLUME 11

YEAR 2017

URL=https://www.frontiersin.org/article/10.3389/fnhum.2017.00117

DOI=10.3389/fnhum.2017.00117

ISSN=1662-5161

4) Window Of Tolerance Concept.

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