The Science Behind Scents: 12 Things You Didn't Know About Aromatherapy
Your perfume, candles, and aromatherapy oils have the power to lift your mood, jog hidden memories, and increase in-store sales.
I've always been ambivalent about aromatherapy's claims and was skeptical about fragrances, perfumes, scented candles and aromatherapy. I love perfume and scented candles, but I've never expected them to improve my state of mind or, as some believe, influence my behaviour. But I had a surprisingly positive experience with a lavender candle while investigating sleep cycles, and the academic research I read at the time made me reconsider my scepticism.
People have been using the essential oils distilled from plants and flowers to calm and heal for millennia. Lavender, the plant most studied for its psychophysiological properties, is wider accepted to be an effective sleep aid. Meanwhile, most people agree that a spritz of lemon or peppermint will perk you up.
Here we delve into the science behind fragrances and aromatherapy, its benefits, the key ingredients and some false claims that you should be aware of.
In recent years, scientists have become more interested in measuring the power of scent – and the results are surprising. Under lab conditions, lavender has been shown to enhance relaxation and drowsiness, improve sleep quality by increasing the proportion of deep, slow-wave sleep, and even reduce the stress and pain of an injection.
There's an emerging school of thought that claims it is possible to harness the emotive power of scent to influence people – so much so that global companies like American Express and Valentino now spend big on scenting spaces where they interact with customers.
Nike hired consultants to blend a perfume that would make its shops smell like a combination of basketball rubber and sports fields. These companies are clearly convinced of the scent-memory emotion-behaviour link, and I want to know why.
"Rosemary is for remembrance" is a famous quote from Hamlet. Here's another quote about rosemary: "Since ancient times, this aromatic herb has been believed to have properties to improve the memory." That one comes from the Australian Army, and is the official explanation as to why we pin a sprig of the herb to our lapels on Remembrance Day.
Humans have long sensed there's a connection between rosemary and memory, and it seems they're onto something. In 2016, researchers at the University of Northumbria put 150 adults through a series of memory tests t0 measure what effect the aroma of rosemary would have on their memory. Some performed the memory tests in an unscented room, while others performed the tests in a room filled with the smell of rosemary. The test scores of those in the room with the rosemary were 15 per cent higher.
The experiment had been designed to test prospective memory – our ability to remember to do something. When Dr. Mark Moss presented the findings to the British Psychological Conference, he said, "This is potentially very important because prospective memory, for example, enables you to remember to take your medication at certain times of a day."
That same year, the Journal of Pharmaceutical Sciences published a review of more than 150 studies that measure how scents change brainwaves. Authors Kandhasamy Sowndhararajan and Songmun Kim wanted to understand what science had observed about smells of all kinds, from magnolia flowers to chewing gum.
All the studies they reviewed used Electroencephalography (EEG) to measure how brainwaves changed when exposed to certain smells. One study looked at how rosemary affected 40 adults' ability to solve simple maths problems. The EEG readings showed the aroma of rosemary decreased frontal alpha and beta power, "suggesting increased alertness". The volunteers were more relaxed and alert and completed the task faster, but not more accurately.
Another study suggested peppermint may be a performance enhancer. "The peppermint odour significantly increases running speed, hand grip, strength, and number of push-ups, but had no effect on skill-related tasks," the study found. It was also shown to "significantly enhance memory and alertness" and, if a peppermint oil is present in a darkened room, people were less likely to become sleep than if there were no odour.
Chocolate was shown to be distracting, while orange aromas calmed people who were waiting to go into a dentist appointment. The researchers concluded: "The aromatic poverties of these products play a major role in the psychophysiology al functions of human beings."
But those who believe in the power of scent say chemistry is just one side of what's happening and that it's the nose's connection to our brain's centres of memory and emotion that gives it its power.
People born before the 1940s associate the smell of wood with their childhood because all their toys we're wooden. For people born after the '40s, images of childhood are conjured by crayon wax, Play-Doh, and plastic.
These are the observations of perfumer Dawn Goldworm, whose company, 12.29, has sold signature scents to clients from Lady Gaga to Bentley on the basis that the link between smell and memory means fragrance can influence emotions and, therefore, behaviour.
The olfactory bulb, which detects smell, is closely connected to the brain's limbic system, which is known for emotion and memory formation.
As awn explains on the 12.29 website: "When you smell an odour, you automatically link an emotion to it. This is why some of our most powerful memories are linked to smell – the smell of freshly cut grass, our Christmas tree, our grandmother's house. No other sense can transport us and make us feel that emotional connection like scent can. All companies should consider the emotional impact they can have simply by adding a smell."
Gold Coast perfumer Emma Leah believes it's possible to create "an intentional, cued pathway" between a specific smell and a positive emotion, so that whenever a person smells that fragrance, the positive emotion is stimulated.
While she was working on a play set in the catacombs of Rome, Emma created a damp aroma to help transport the audience underground. She also created a scent to help actors conquer stage fright. "We created a safe environment. We had a relaxation exercise with a scent. Later, when they smelled that scent, the actors went back to that relaxation," Emma says. "We created a scent pathway."
Anyone who has ever smelled the perfume of an old lover, or an old enemy, will know how effective fragrance is at stirring up emotions. According to Dawn, mood manipulation can work on a large scale because so many of our scent preferences have cultural roots.
"The smells you like or don't like are not your own, subjective opinion. They are almost entirely informed by your culture, your generation, and your living environment from the first 10 years of your life," she says.
In the '90s, US tie store Knot Shop started pumping the smell of leather, oak, and tobacco into its retail outlets. The idea was to make the stores smell like the ideal man, so that female customers – the primary purchasers – would spend more. But, after four months, the scent experiment was abandoned. When The New York Times reported on the failure, the president of the company, Gene Silverberg, said maintaining the fragrance wasn't worth the trouble. "Without the smell, I haven't seen any drop in sales," he told The Times.
"The general idea of scent affecting mood is quite accurate, but it all has to do with your experience of scent in the first place," Emma says. "My opinion is, yes, it can be used to motivate people and help with mood control, but you have to be careful. Fresh dirt is something everyone loves because it's primary, but not if they've had a bad experience with it. It can make people feel a little bit sick."
Because the science around scent and emotion is still so unclear, it's an area that is open to deception. In the early 2000s, there was a boom in scent marketing when an eccentric neurologist, Alan R. Hirsch, started touting studies he'd done that supposedly showed the power of scent. He was interested in the idea that scent could be used to suppress appetite and aid weight loss.
However, in 2014, his company was fined US$26.5 million for deceiving consumers. Alan Hirsch "gave endorsements that were not supported by scientific evidence", the US Federal Trade Commission found.
While researching this article, I received an unsolicited email from a PR company promoting a line of essential oils with a list of promises ranging from the medically improbable ("Frankincense... enhances nerve function") to the fantastical (a blend containing orange, ginger, and clove will "enhance the frequency of the harmonic magnetic energy field"). The Utah-based company, Young Living Essential Oils, is one of the largest manufacturers of essential oils in the world. Five millilitres of its rose oil costs AU$418.
Despite their popularity, the company has also been caught making false claims. Last year, the US National Advertising Division told Young Living to stop saying its products were therapeutic. This followed a caution from the US Food and Drug Administration in 2014 for claims that its products could cure Ebola – specifically, that the Ebola virus cannot survive in the presence of oregano.
Emma says there are a lot of false statements about the efficacy of oils and aromas, which damages the field's reputation. Some companies "are peddling things that are not real and they are making huge claims about them, and it's difficult to get any kind of guarantee because there's so little scientific testing," she says. "It makes us all look bad. I'm not affiliated with that. I make perfumes out of beautiful ingredients and that's that."
It seems that regardless of what science says, familiar and wonderful smells entice us. Until recently, Australians could claim aromatherapy through their health insurance. Even as the federal government cut it from the list of eligible therapies, its review team admitted there was evidence to suggest it may be effective in reducing anxiety and alleviating pain. The existing body of research simply wasn't rigorous enough, and the government concluded the effects of scent remain "uncertain".
But it's an are that's attracting interest and I'm sure about that, in time, we'll learn more about the science of scent. In the meantime, I'm conscious that I am creating scent memories every day, so I won't forget to stop and smell the roses.
Text: Bauer Syndication