The Big Idea
Smell is an incredibly evocative sense. We suspect most of you will know what it feels like to have a sudden rush of emotion and memory when you unexpectedly catch a scent that takes you back – like the smell of a former flames’ perfume or the smell of that pink soap (tar soap) schools used to use. We say most people because we know that one of the key senses reduced or lost when infected by COVID-19 is smell. The fancy term here is anosmia – which can be short term, say due to illness, or longer term even permanent.
Smell has been used to help with mood, treat illness and attract, as well as repeal, for probably as long as we have been humans. Of course some animals, such as dogs, have much greater sensitivities to smell than our own. And many animals use smell as a means of surviving by hunting, or being alert to predators, communicating with each other, which includes where to find calorific food or even choosing a mate. Basically smell is a big thing in the animal kingdom and yet we so often overlook it as a sense – that is until we lose it when we have an illness like a cold, COVID or suffer from say, hay fever.
The power of scent is not news to the initiated and the likes of aromatherapists or people who sell scent diffusers for our homes and workplaces. The use of aromas for therapy have been used since ancient days to the Greeks, Ottomans, Egyptians and Romans. Despite aromatherapy being all too often dismissed as a pseudoscience, there does seem to be significant evidence that stimulating the sense of smell can be complementary approach to help us ‘get into’ more relaxed states, to be more likely to buy products, attract a mate and even to have a better memory.
You might notice from this photo of Dulcie that lavender (and the scent of lavender in natural pillow sprays) is a common sleep aid for many! The smell of lavender may even have some other unexpected impacts. For instance a small study that involved 90 people found that the aroma of lavender was more effective than a control in promoting a sense of trust among strangers.
So what is going on here? Could your sense of smell being overlooked? Is smell all it’s cracked up to be – can it really be useful, even therapeutic?
Got it…What’s the Science
When we smell, which is all of the time (unless you have anosmia) scents are inhaled compounds interact with, and are absorbed through, the olfactory bulbs in our noses, which send messages to our olfactory cortex – this is the part of the brain responsible for our conscious sense of smell. These messages quickly reach other areas of the brain, such as the limbic system – which includes structures such as the hippocampus (memory and learning) and amygdala (associated with memory of fear and danger). Together these structures of the limbic system are involved with memory and emotion. The olfactory bulbs and system are literally directly ‘plugged in’ to our regions of our brain involved with association of stimuli with memories of events, emotions and places. So when we think of it this way it is not too surprising that certain scents / aromas get linked with certain events, places or feelings (moods). What seems key here is that early life or strong associations help make, for better or for worse, strong associations that can evoke strong emotions and physical reactions such as raised heart rate and breathing.
Aromatherapy involves inhaling essential oils, either via a diffuser which sends particles into the air or by being massaged into the skin after being mixed with a carrier oil. The way in which certain scents are selected to treat clients or patients can range from the clients’ preference to what the aromatherapist believes will help with certain conditions. Now this where we believe we straying between what is clinical therapy and what is conscious manipulation of senses to change our mental states. It’s this blurring that we need to be careful of and where aromatherapy can get a bad rep by making exaggerated claims to be able to treat and cure conditions through the olfactory system. As regular attenders to our lives and readers of The52Project tip blogs will probably pick up here is, while keeping this caution in mind, we should not underestimate the power of the brain, as a physiological entity, to impact the rest of the body as an entire physiological entity – as well as the mind.
Amazingly neuroscientists are still working out how we actually smell. For instance, there has been much speculation of how the classical receptor model on the olfactory bulbs is not sufficient to account for the complexity of the sense and say how it can respond to new smells that we don’t have receptors for. More contemporary theories include the quantum energy of scent molecules… So smell could be quantum!
Also there could be much more going on here than just scent and the sense of smell. Our olfactory bulbs and the nerve cells are quite primitive as sense organs go, jutting out into our environment, lying just below and in the thin nasal mucosa of our nasal passages. Scientists have shown that smelling essential oils that contain terpenes can lead to them entering your blood stream via the nasal mucosa – and because the compounds are small and fat-soluble the “smells” can easily cross the blood-brain barrier. Terpenes are found in many aromatic plants, including eucalyptus, bay, wormwood and sage.
You might have heard of this quote from Hamlet – Ophelia says “There’s rosemary, that’s for remembrance” – well that’s not such a wild claim – especially as rosemary plants contain terpenes. A small study done at Northumbria University found that rosemary might improve test scores among school-aged children. They scented some rooms with rosemary and left some rooms unscented. The children who took tests in rooms scented with rosemary received higher scores than children in unscented rooms. A study by the same team used blood samples to detect the amount of terpene molecules that participants had absorbed from smelling rosemary oil. The researchers then did speed and accuracy tests, and mood assessments, to judge the rosemary oil’s affects. It is unclear whether this is due to the association that the smell and/or terpenes have with learning here or whether there is something more traditionally pharmacological going on. Despite being a small study, it did show that higher concentrations in the blood of the terpenes did impact an individual’s cognitive performance – higher concentrations resulted in improved performance. Both speed and accuracy were improved, suggesting that the relationship is not describing a speed-accuracy trade off.
Meanwhile, although less pronounced, the rosemary also had an effect on mood. More rosemary terpene in the blood = more positive mood. The team also tested attention span and alertness and found it had no significant impact. So certainly smelling some rosemary oil could do you some good if you have low mood or your children are about to take some GCSE or A’Level testing soon! Especially if they study and associate that smell with learning. You/they could even try having different scents for certain subjects…
Lavender is a smell that most people recognise and studies suggest that the scent of lavender is calming for us and other animals. A review of studies concluded that lavender may offer some small to moderate sleep-promoting benefits, although it the authors call for more rigorous studies that investigate the use of lavender to promote sleep and the mechanisms by which it is acting. Dulcie’s own view is regardless of whether the effects are “real” – due to interaction of terpenes and / or by a contextual association with the place and time to sleep – or the result of the placebo effect, she even has travel versions of her sprays as she swears by them when her brain is too busy to get to sleep!
What we need to be careful of here is the rush to say that it is the chemicals (terpenes) that are making the difference alone and then rushing to buy oral supplements or snorting bucket loads. A fairly robust study with 500 people and proper placebos found that lavender oil capsules helped with anxiety – but some people had some pretty unpleasant side effects like nausea, belching and diarrhoea. So as with any of our tips, get medical advice if you are at all uncertain and try a little – not a lot! – (Small joke there for those of you who are old enough to remember Paul Daniels!) Also that perhaps, like with phytoncides in forest bathing / walking (#Tip11), we have actually evolved to take the benefits of these compounds through the process of breathing and smelling. If so this would also suggest we have to make small adjustments, like a few drops of essential oil onto a tissue, to have the impact that we are after. We all know what how overpowering and swamping it can be when we walk into the presence of someone who has doused themselves with a potent cologne.
It seems we can be more certain that we can use scents to modulate our mood and environment to define context which the brain finds very useful in making memories and how we respond to them more ‘sticky’ and literally visceral. This is most likely why we are drawn to scents that we associate with reward and enjoyment. There is some real science and method in the estate agent suggesting baking bread if you are trying to sell your house. So we can use this to bring more to our experience and in control of our world.
The involvement of smell also goes much deeper than for the purposes of this particular blog. For instance pheromones are substances that we sense through smelling them that are involved usually subconsciously with the selection of a mate. There is a fair amount of evidence that this is involved in the selection of mates that confer better immunity by improving the mix of genes for histocompatibility complexes that are used by our bodies to mount a immunological response to an infection. The better the breadth of the mix the better the chance that resulting offspring twill be able to fight diseases and infections. So we tend to seek mates with much different histocompatibility complexes than our own. This is why, as pheromones are in sweat, some people’s sweat, namely a partner’s, is less offensive, even attractive, than others’ and vice versa.
So there is a lot to smell and a lot more to be fully understood.
Watch our #Tip15 on the Instagram Live Recording….
*Small gaff alert: Dr. Iain got his cranial nerves mixed up this morning! The olfactory bulbs are in fact the first cranial nerves, not the second.
Read an example of why we are attracted to, and repelled by, certain smells like toast here.
“There’s Rosemary, that’s for remembrance.” – audio with Dr Mark Moss
Smell is a sense we can easily underestimate and yet is also one that we can so easily use to help us modulate our mood, a bit like music (#Tip12), and even cognitive performance. It could be used to help you get that exam mark or even your ideal partner!
Just be careful. As one of our test partners DigitalJen (@digi_jen) warns us in her tale below, some scents can lead to adverse and allergic reactions. So again if you do suffer from allergies or sense adverse affects from trying this tip do stop using it.
Interestingly smell training is being recommended as part of the recovery of those who have lost the sense of smell due to Covid.
Random facts from DigitalJen time (her own words)… the hospital where I had my son actively used aromatherapy (to the extent many of the midwives did additional courses in it) for appointments, women waiting for C-sections, in labour (changing it for the stages of labour) and post delivery…. Other random fact is that I used to be a buyer for a garden centre and did some training on smell for when you’re choosing which candles to stock… Never sniff the candle, always sniff inside the lid as that will give you a better sense of what the smell will be.
Also be warned! Some fragrances use in product such as candles and oils are so pure they set off my food allergies – so some scented Christmas candles (and all citrus ones) make me itch like crazy!
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