The Science of Aromatherapy
An investigation into scent as a legitimate wellness tool
If you’ve ever lit a scented candle to relax or soaked in a lavender bubble bath, you’re already familiar with the power that smell can hold over mood. Of all five senses, it’s the one most closely linked to emotion and memory — likely, scientists think, because the brain’s olfactory processing center is so close to the regions in charge of those other two functions. And there’s an extensive body of research suggesting smell can affect us physically, too: Lab studies have found lavender, for instance, to be effective in calming the nervous system, and neroli, a stimulant, has been shown to increase heart rate.
It makes sense, then, that aromatherapy — the use of scents, most often from essential oils, to enhance well-being — is having a moment right now. With the growing cultural conversation around self-care, people are increasingly incorporating smell into their routines to relax, to fall asleep, to focus, or to get themselves energized. Some estimates put the global market size for aromatherapy at $1.2 billion, and in the U.S., the essential-oil market has grown steadily over the last five years. The market is projected to keep growing at a steady pace through 2025, transforming these products from quaint home remedies to one of the most accessible, and affordable, tools for wellness. Unlike so many other practices in the space, filling your home with a specific scent doesn’t take much effort.
And there’s evidence to suggest it really can work, to an extent — especially, and perhaps only, if you want it to. The science of aromatherapy might best be understood as a study in the power of suggestion. It can also be a strong emotional trigger. Because smell is so tightly tied to memory, the effect of a given scent depends in large part on how you’ve experienced that scent in the past.
The research on aromatherapy is somewhat limited, and a 2012 reviewconcluded that it hasn’t been proven to be a viable treatment for any diagnosable medical conditions. When it comes to improving people’s mental or emotional state, studies have yielded mixed results, but many of them point to belief as a key ingredient: If you believe a scent will make you more joyful, calm, or courageous, it likely will. In 2004, for example, Estelle Campenni, PsyD, a professor of psychology at Marywood University, found that our emotional response to essential oils actually has more to do with our beliefs than the oils themselves. Lavender oil, when she labeled it as relaxing, consistently slowed participants’ heart rates, while neroli, which she introduced to participants as a stimulant, had the reverse effect. When Campenni switched the labels, telling participants that lavender was a stimulant and neroli was a relaxant, their heart rates reacted accordingly.
Technically, the Food and Drug Administration bars essential oil companies from marketing or claiming specific health outcomes. But plenty of manufacturers foreground their products’ mental or emotional potential: For example, essential oil giant Young Living, which boasted $1.5 billion in sales in 2017, promotes “emotional well-being” with oils named for positive emotional experiences like Valor, Harmony, Joy, and Inner Child. And the Aroma Freedom Technique, created by clinical psychologist Benjamin Perkus, claims to help with the processing of trauma; by smelling essential oils in a therapy-like setting, Perkus argues, people can learn to disconnect painful memories from anxious responses.
Experts agree that claims like this are overkill: “Someone might smell a lily and remember their parent’s funeral and have an emotional experience — it happens all the time,” says Keith Humphreys, Ph.D, professor of psychiatry and behavioral sciences at Stanford University. “Sure, scent is linked to our memories. But that doesn’t mean it changes the brain.”
Still, while a scent-induced shift in mood is a far cry from forming new neural pathways, Campenni says aromatherapy can still be a useful mental health aid. “For me, the danger is that people are equating a change in the state of relaxation with a change in the experience of anxiety or depression. That’s a pretty big leap,” Campenni says. “But when it comes to changing one’s mood, using scent makes sense — augmenting psychotherapy to facilitate a change in state could be effective.” By choosing scents that most people regard as soothing or cheerful, therapists can use aromatherapy to create a warm, calming environment for their clients.
A practitioner’s authority can also help persuade clients to be receptive to these scents, Campenni notes; if a therapist, a trusted source, tells a patient that what they’re smelling may make them feel a certain way, the power of suggestion will be that much stronger in making it so.
Similarly, Humphreys says oils can be used as a kind of prop that adds a sense of gravity to the therapy session, prepping the client to believe that they’re being set up for success — much like how the trappings of a therapist’s office facilitate an environment of trust. “You could say the traditional psychiatrist’s office, with a leather couch and degrees hung on the wall, primes people for change in the same way,” Humphreys says.
Aromatherapy, then, is less a straightforward path than it is a choose-your-own adventure practice. And while it’s certainly not proven to be a mental health treatment in its own right, it can be a powerful ritual for the easing of lesser ailments, whether that’s at home or in a more structured setting. “Our minds are connected to our bodies, so what we believe about a scent can override its actual properties,” Campenni says. “Think about when you buy a candle that’s labeled ‘relaxing’ or ‘sensual.’ There’s always a suggestion that goes with it. That’s why placebos work — because you believe they’re going to.”