• Molly Taft

The Science of How Essential Oils Boost Mood

By Molly Taft, Originally published on Lark Magazine


Everything you need to know about how aromatherapy really works. Neuroscientist and leading scent expert Rachel Herz, Ph.D., explains the science of scent and emotion.

Rachel Herz, Neuroscientist and leading scent expert


Smells, memories, and emotions are all tightly bound together in our cultural conversation. One of the earliest mentions of smell and emotion in modern literature is in French author Marcel Proust's In Remembrance of Things Past. Anyone who took an English class in college will undoubtedly remember the famous passage where the author is transported back to his childhood just by tasting a madeleine cookie dipped in tea.


But there’s more to it than traveling through time or the age-old history of aromatherapy.

There’s been an increase in clinical studies focused on aromatherapy in the past 30 years, and Rachel Herz, a neuroscientist at Brown University, was one of the first scientists to study the interaction between scent, psychology and biology. Her work separates the folklore of aromatherapy from the science of the effects of scent on human cognition, emotion and behavior.


When I first started my PhD, no one was studying how scents could manipulate mood,” Herz said. “Then one paper came along which showed that smelling a pleasant odor put people in a good mood, and smelling an unpleasant put them in a bad mood. The authors speculated that it was due to the basic evolutionary meaning of scents and how scents are processed in the brain, and this set off a lightbulb in my brain!"


Herz became fascinated by the unique connection between the sense of smell, emotion and memory. She’s since become a leading expert on the psychological science of smell, authoring three books and more than 90 research articles on the topic. Some of her major academic contributions include showing how odor-evoked memory is emotionally unique, how "aromatherapy" really works, and how emotional associations to odors can change our moods and behavior.


“It became clear to me that regardless of other factors there is a psychological mechanism that underlies the brain’s response to scent,” she said.


And this mechanism includes aromatherapy and essential oils. Many people may think of aromatherapy as a purely holistic exercise with no scientific roots. But Herz’s work shows that scents used in the practice produce psychological reactions that are anything but imaginary.


Aromatherapy is real. Mood, behavior and thoughts do change. But it works through the way our own mind and brain works.

When a scent activates the brain, it can seem as though it has drug-like effects—but our psychology is really at the root of this reaction. There are a couple of conditions that need to be present to see this effect: the smell needs to be at a detectable level, and we need to be at least slightly aware of it. When these two conditions are met, a response occurs – meaning that there are scientific and psychological mechanisms at play in a true neuroscientific sense.


At the inhalation of a smell, receptors in our nose are activated which sends signals to our brain. As soon as we consciously register the scent, specific emotions and moods are triggered.


Dr. Herz sat down with Mindalt to talk more about the science of smell, how our brains and our bodies respond to scent, and how to use essential oils to hack your moods.


Read the Q & A here.