Aromatherapy Alleviates Anxiety Via Your Vagus Nerve

Aromatherapy calms your autonomic nervous system by engaging the vagus nerve.

Posted Nov 09, 2017

What are some of your earliest scent-based childhood memories? In Remembrance of Things Past, Marcel Proust famously describes the ability of a distinctive smell to bring back a wave of long-forgotten childhood memories as if it was yesterday. When the protagonist, Charles Swann, dips a madeleine cookie into a cup of tea, he has vivid flashbacks to his youth. The latest research on aromatherapy reaffirms that you can encode certain smells to trigger specific autonomic responses in your nervous system that lower anxiety and improve your mood in a "Proustian" way. 

plprod/Shutterstock
Source: plprod/Shutterstock

When you recall happy scents from your childhood, don’t the smells of Silly Putty, Play-Doh, and Crayola Crayons bring back a wave of positive memories and evoke a playful state of arousal? As a time-date stamp, these smells always remind me of the "warm-fuzzy" feeling of watching Mr. Rogers' Neighborhood while curled up in a beanbag chair on shag carpeting.

I was born at New York Hospital on the Upper East Side of Manhattan in 1966. Because of this, urban smells like wet concrete on the sidewalk just after it starts to rain, stale gasoline in subterranean parking garages, and the steam given off by the Sabrett hot dog cart that was always at the corner of 68th and York (and is still there today) are among my most indelible odor-based childhood memories.

When I was growing up in the early 1970s, my family lived across the street from New York Hospital in “Phipps House.” At the time, my father was doing his neurosurgery residency at Cornell Medical School, which is now called New York-Presbyterian/Weill Cornell Medical College. Interestingly, a new study by a team of surgeons at my dad's alma mater was published yesterday which reaffirms the power of aromatherapy to reduce patients' anxiety before heading to the operating room. These findings were published online, November 8, 2017, in the journal Laryngoscope Investigative Otolaryngology.  

The authors describe the main takeaway of this study in the abstract: “Aromatherapy, the therapeutic use of essential oils extracted from aromatic plants, may offer a simple, low-risk and cost-effective method of managing preoperative anxiety.” Although the benefits of aromatherapy may be short-lived, the researchers see the anxiety-reducing influence of lavender aromatherapy as statistically significant.

The Cornell researchers emphasize that more research is needed to confirm the clinical efficacy of aromatherapy. That said, senior author Ashutosh Kacker, of New York-Presbyterian/Weill Cornell Medical College, concluded: "Given the simplicity, safety, and cost-effectiveness of aromatherapy, healthcare providers should consider its use for managing preoperative anxiety."

Although aromatherapy often gets a bad rap for being new-agey or woo-woo, there are countless animal and human clinical studies which show that aromatherapy has a profound impact on the autonomic nervous system (ANS) and can reduce “fight or flight” distress by activating the calming effects of our parasympathetic vagus nerve response.

Notably, taking a deep whiff of anything by inhaling through your nose followed by a long exhale from your mouth is a form of diaphragmatic breathing that is going to calm your ANS by squirting out some vagusstoff (German for "vagus substance") which slows heart rate and alleviates anxiety. (For more on this check out: "Diaphragmatic Breathing Exercises and Your Vagus Nerve.")

From an evolutionary standpoint, olfaction is our most primal of the five senses. Scent is often the first warning sign of danger or that you are safe and sound. For example, just as the smell of Thanksgiving dinner being prepared at your family’s home can make you feel cozy and stress-free on a parasympathetic level rooted in our evolutionary biology, other smells can trigger fight-or-flight responses that evolved as part of our survival instincts. As a fear-based example, the smell of diesel gasoline is notorious for triggering PTSD responses in combat veterans who associate this smell with wartime transport.

Wellcome Library/Public Domain
This early anatomical drawing of the "wandering" vagus nerve illustrates how the extensive "vagus-brain axis" modulates the autonomic nervous system (ANS) and influences our mind-body connections during aromatherapy.
Source: Wellcome Library/Public Domain

I’ve been researching and writing about the psychophysiological benefits of aromatherapy for over a decade, as exemplified by the chapter “Remembrance of Things Past: Olfactory Encoding in Sports" from The Athlete’s Way: Sweat and the Biology of Bliss (St. Martin's Press). In 2002, a study, “Autonomic Nervous System Responses to Odors: the Role of Pleasantness and Arousal,” found a correlation between odor ratings (intensity, arousal, pleasantness, and familiarity) and activation of the excitatory SNS and inhibitory vagus-based parasympathetic nervous system (PNS). These responses were dependent on personal preferences and pleasantness associated with specific olfactory stimuli, which are referred to as “odor hedonics."

In recent weeks, I’ve aggregated mountains of new empirical evidence on how “Aromatherapy Can Optimize Your Autonomic Nervous System and Minimize Distress" as part of my research for the Guts-Wits-and-Grace Under Pressure book I'm currently writing. (Please see the reference box below for a smorgasbord of animal and human studies showing various ways that aromatherapy can reduce anxiety and lower distress by modulating the parasympathetic response of your autonomic nervous system via the vagus nerve.)

Photo by Christopher Bergland
As an athlete, I used aromatherapy to optimize my psychophysiology and performance. I've held onto these essential oils from the past for nostalgia. Each vile is like a time capsule that takes me back to a specific place and time in a Proustian way.
Source: Photo by Christopher Bergland

Anecdotally, I stumbled on the power of olfactory encoding to simultaneously maintain "guts-wits-and-grace" as an ultra-endurance athlete when I was competing internationally in Ironman triathlons around the world. Because Kiehl’s Since 1851 was my title sponsor, I had access to over 170 different essential oils and would make a unique blend of fragrance in the weeks leading up to a big event to embed associations linked to a target “athlete’s way mindset" of optimism, eustress (good stress), and equanimity when venturing to unknown lands to compete in "quixotic” adventure races. As a retired professional athlete, I continue to use a wide range of scents to maintain an optimal ANS profile using aromatherapy.

Just like someone might keep a Xanax in his or her hip pocket in case of a panic attack, I keep a small atomizer of calming fragrance close by and spritz myself whenever I need to maintain serenity in times of potential distress. Sustaining a calm but enthusiastic state of arousal in your ANS facilitates the ideal mindset for hitting it out of the park in both sport or life. Anyone can use his or her sense of smell to promote a state of peak performance on and off the court.

Through the lens of a psychophysiology, aromatherapy helps to modulate an optimal state of arousal and positive emotional valence associated with a perfect blend of adrenaline and acetylcholine. This combo also reflects the sweet spot between “boredom and anxiety” which facilitates a "flow" state and/or superfluidity (the highest tier of flow).

Wikimedia/Creative Commons

This "adrenaline response curve" illustrates that being over-aroused (as marked by having too much adrenaline and not enough "vagusstoff" in your autonomic nervous system) or under-aroused (as marked by not enough "eustress") can lead to poor performance. 

Source: Wikimedia/Creative Commons

Aromatherapy can help you tap into a state of "maximum performance" and optimal arousal as represented by the zenith of the "inverted U" in the diagram to the left. Along this line, one of my favorite aromatic blends for athletic performance used to be patchouli oil and Coppertone sunscreen. When I was younger, the combination of these two smells never failed to create a perfect mix of inhibitory vagusstoff and excitatory adrenaline in my ANS. More specifically, I have a hunch that the subdued earthiness of patchouli kept my inhibitory vagus response robust while the exuberant and uplifting associations of summertime, sunshine, and blue skies held in the iconic Coppertone fragrance boosted my SNS with a shot of adrenaline. Of course, this hypothesis is just a speculative educated guess. That said, I burned out on the smell of patchouli and find this particular essential oil to be overbearing and cloying at this stage of my life.  

We all know that olfaction is deeply personal and affects our emotions and state of mind in unique ways based on your particular associations with a scent. The best news is that you can easily fine-tune specific aromatherapy odors to trigger whatever mood and level of arousal you want to reinforce within your autonomic nervous system at any given time. Remember: Aromatherapy is a powerful anxiety-busting tool that is always readily available and within the locus of your control.

References

Wotman, Michael, Joshua Levinger, Lillian Leung, Aron Kallush, Elizabeth Mauer, Ashutosh Kacker. "The efficacy of lavender aromatherapy in reducing preoperative anxiety in ambulatory surgery patients undergoing procedures in general otolaryngology." Laryngoscope Investigative Otolaryngology (First published online: November 8, 2017) DOI: 10.1002/lio2.121   

Trambert, Renee, Mildred Ortu Kowalski, Betty Wu, Nimisha Mehta, and Paul Friedman. "A Randomized Controlled Trial Provides Evidence to Support Aromatherapy to Minimize Anxiety in Women Undergoing Breast Biopsy." Worldviews on Evidence‐Based Nursing (Published online: September 29, 2017) DOI: 10.1111/wvn.12229

Zhou, Lanxi, Motoko Ohata, Chisato Owashi, Katsuya Nagai, Issei Yokoyama, and Keizo Arihara. "Odors Generated from the Maillard Reaction Affect Autonomic Nervous Activity and Decrease Blood Pressure through the Olfactory System." Journal of the Science of Food and Agriculture (First published: August 16, 2017) DOI: 10.1002/jsfa.8538

Tomi, Kenichi, Eri Sakaguchi, Saki Ueda, Yasuki Matsumura, and Takahiro Hayashi. "Physiological and Psychological Effects of Rose ‘Wishing’ Flowers and Their Hydrosols on the Human Autonomic Nervous System and Mood State." The Horticulture Journal (Published: January 31, 2017) DOI: 10.2503/hortj.MI-098

Matsumoto, Tamaki, Tetsuya Kimura, and Tatsuya Hayashi. "Aromatic effects of a Japanese citrus fruit—yuzu (Citrus junos Sieb. ex Tanaka)—on psychoemotional states and autonomic nervous system activity during the menstrual cycle: a single-blind randomized controlled crossover study." BioPsychoSocial Medicine (Published: April 21, 2016) DOI: 10.1186/s13030-016-0063-7

Chien, Li-Wei, Su Li Cheng, and Chi Feng Liu. "The effect of lavender aromatherapy on autonomic nervous system in midlife women with insomnia." Evidence-Based Complementary and Alternative Medicine (2012) DOI: http://dx.doi.org/10.1155/2012/740813  

Duan, Xudong, Manabu Tashiro, D. I. Wu, Tomoyuki Yambe, Qingtian Wang, Takehisa Sasaki, Kazuaki Kumagai, Yun Luo, Shin-ichi Nitta, and Masatoshi Itoh. "Autonomic nervous function and localization of cerebral activity during lavender aromatic immersion." Technology and Health Care (2007)  

Kuroda, Kyoko, Naohiko Inoue, Yuriko Ito, Kikue Kubota, Akio Sugimoto, Takami Kakuda, and Tohru Fushiki. "Sedative effects of the jasmine tea odor and (R)-(−)-linalool, one of its major odor components, on autonomic nerve activity and mood states." European Journal of Applied Physiology (2005) DOI: 10.1007/s00421-005-1402-8

Niijima, Akira. "Effects of fragrance stimulation of lavender oil on autonomic nerve activity in anesthetized rats." Proceedings of Annual Meeting of the Physiological Society of Japan. (2004) DOI: http://doi.org/10.14849/psjproc.2004.0_S197_3

Bensafi, Moustafa, Catherine Rouby, Vincent Farget, Bernard Bertrand, Michel Vigouroux, and André Holley. "Autonomic nervous system responses to odours: the role of pleasantness and arousal." Chemical Senses (2002) DOI: 10.1093/chemse/27.8.703

Alaoui-Ismaïli, Ouafae, Evelyne Vernet-Maury, Andre Dittmar, Georges Delhomme, and Jacques Chanel. "Odor hedonics: connection with emotional response estimated by autonomic parameters." Chemical Senses (1997) DOI: 10.1093/chemse/22.3.237

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