Mariel Tishma
Chicago, Illinois, United States

What smells good to you? Do you know why? To many people smell seems of little significance, yet it is a powerful sense, having evolved earlier than the more complex senses of sight and hearing.^{1, 2} Smell is unique in how it is processed, being first detected by neurons which dangle into the nasal cavity and end in the brain.³ From there, smell information moves to the limbic system, which is responsible for “controlling mood, memory, behaviour and emotion.”⁴ Smell is the only sense with such an intimate connection to the brain.⁵

This connection offers interesting health challenges and potential benefits. Smell may affect mood, but the relationship between the two is not direct. There are no smells certain to improve or even change emotions. Rather than working like a prescription, “we work on [smells] through our experiences with them.”⁶ One can make assumptions based on place and culture but “there are no inborn preferences in olfaction.”⁷ Almost all responses come out of an individual’s association with a smell. So the roses that remind one person of childhood may remind another of a grandparent’s funeral.

One study found that by inducing anxiety in subjects, “initially neutral odors become unpleasant,” so that even a neutral smell like disinfectant in a hospital could become tied to negative emotions.⁸ And hospitals — with their memories of disabling illness, painful treatments, and challenging diagnoses — certainly have a high potential to form negative associations and emotions.⁹ Not to mention that underneath the smell of disinfectant also comes the smell of infection, waste, or blood. This may explain why so many patients hate the smell of hospitals. Likewise, in one study of patients with dental phobia, the smell of the dental office was “given high importance” in the intensity their fear.¹⁰

So what does that mean for medical professionals? Firstly, patients who already dread treatment may have an additional spike in anxiety on simply smelling the air where they are treated, which could affect their response to certain therapies. It also means that medical staff may be confronted by a scent which is negatively affecting them as much as patients, even when the smell “can no longer be consciously perceived.”¹¹

While there are few universally bad smells, in another study participants exposed to an odor they considered unpleasant “noted a bad mood, a high level of anxiety, tiredness and sadness,” which may add to existing hospital stressors.¹² While stress can be useful in some situations, persistent stress may lead to further damage in those already weakened by illness. Stress is associated with slower wound healing and stress hormones suppress immunity by affecting cytokine profiles.¹³

By contrast, however, certain smells may have a positive effect on well-being. Studies have indicated that “mood is better when the odour is pleasant,”¹⁴ whatever that definition of pleasant turns out to be.^{15, 16, 17} Pleasant ambient odors can change one’s perceptions of people,¹⁸ increase alertness and calmness,¹⁹ encourage productivity and sociable behaviors,²⁰ reduce anxiety,²¹ and produce an overall relaxing effect.²² A positive ambient odor may support recovery from major illness, which has been associated with depression.²³ It may also improve the working environment for physicians and other health care workers, who experience high rates of burnout.²⁴

It has been suggested that “philosophers have often slighted … the sense of smell,” and modern medicine may be doing the same.²⁵ While alternative medicine like aromatherapy cannot replace traditional medicine, its supporters suggest it is effective in situations as intense as coping with labor pains or relieving the side effects of chemotherapy.²⁶ Studies have not yet proven if aromas improve immune or health responses directly – for example one study found lemon and lavender scents lowered immune response²⁷ while another stated that ambient lemon odor decreased symptoms.²⁸ However, if a patient associates an aroma with health and positive mood, it may be a helpful adjunct when used alongside proper treatment.

Because of their intimate connection with memories, smells give emotional context to experiences and help us “feel at home in the world.”²⁹ In the construction and redesign of hospitals, considering additional factors like natural light, color, noise levels, control of the environment, and smell may impact the well being of both patients and health care providers.³⁰ If the environment can be used to the advantage of patients it should be considered an asset, not an obstacle. And while it is true that smell is mysterious, hard to manipulate, and difficult to assess, that does not mean it should remain forgotten.

Endnotes

1. “Psychology And Smell,” Fifth Sense, n.d., accessed December 11, 2018, http://www.fifthsense.org.uk/psychology-and-smell/.
2. Tom Stafford, “Why can smells unlock forgotten memories?” BBC, published March 13, 2012, accessed December 11, 2018 http://www.bbc.com/future/story/20120312-why-can-smells-unlock-memories.
3. Ana M Koatz, “The Smell, that Forgotten Sense,” International Journal of Pulmonary & Respiratory Sciences volume 2, no. 3 (October, 2017): 001, accessed December 11, 2018, https://pdfs.semanticscholar.org/45a2/a81ff8e8d1a82445d853da1a6890123c7f7f.pdf.
4. “Psychology And Smell,” Fifth Sense.
5. Tom Stafford, “Why can smells unlock forgotten memories?”
6. Rachel S. Herz, “Do scents affect people’s moods or work performance?” Scientific American, n.d., accessed December 11, 2018, https://www.scientificamerican.com/article/do-scents-affect-peoples/.
7. Egon Peter Köster, “The Specific Characteristics of the Sense of Smell,” in Olfaction, Taste, and Cognition, ed. Catherine Rouby, Benoist Schaal, Danièle Dubois, Rémi Gervais, and A. Holley, 1st ed., (Cambridge, United Kingdom: Cambridge University Press, 2002),  32.
8. Elizabeth A. Krusemark, Lucas R. Novak, Darren R. Gitelman and Wen Li, “When the Sense of Smell Meets Emotion: Anxiety-State-Dependent Olfactory Processing and Neural Circuitry Adaptation,” Journal of Neuroscience 25, (September, 2013): accessed December 11, 2018, https://doi.org/10.1523/JNEUROSCI.1835-13.2013.\
9. Donald S. Kornfeld, “The Hospital Environment: Its Impact on the Patient” in Coping with Physical Illness. Current Topics in Mental Health, (Boston, MA: Springer, 1977), 239, https://doi.org/10.1007/978-1-4684-2256-6_16.
10. J. Lehrner, Christine Eckersberger , P. Walla , G. PoÈtsch ,and L. Deecke, “Ambient odor of orange in a dental office reduces anxiety and improves mood in female patients,” Physiology & Behavior volume 71, (2000): 85, accessed December 11, 2018, https://doi.org/10.1016/S0031-9384(00)00308-5.
11. Egon Peter Köster, “The Specific Characteristics of the Sense of Smell,” 31.
12. Maya Naja, Joël Bree, Judith Lynne Zaichowsky, “The use of ambient scent to improve children’s hospital experience,” Journal of Marketing Trends. 1. (2012): 7, accessed December 11, 2018, https://www.researchgate.net/publication/283087143_The_use_of_ambient_scent_to_improve_children’s_hospital_experience.
13. Neil Schneiderman, Gail Ironson, and Scott D. Siegel, “STRESS AND HEALTH: Psychological, Behavioral, and Biological Determinants,” Annual review of clinical psychology volume 1, (2005): accessed December 11, 2018, 10.1146/annurev.clinpsy.1.102803.144141.
14. Maya Naja, Joël Bree, Judith Lynne Zaichowsky, “The use of ambient scent,” 7.
15. Neil Schneiderman, Gail Ironson, and Scott D. Siegel, “STRESS AND HEALTH”.
16. Marc Schweitzer, Laura Gilpin, and Susan Frampton, “Healing Spaces: Elements of Environmental Design That Make an Impact on Health,” The Journal of Alternative and Complementary Medicine Volume 10, Supplement 1  (2004): S-74, accessed December 11, 2018, https://doi.org/10.1089/acm.2004.10.S-71.
17. Maya Naja, Joël Bree, Judith Lynne Zaichowsky, “The use of ambient scent,” 7.
18. Egon Peter Köster, “The Specific Characteristics of the Sense of Smell,” 31.
19. Sandra T. Weber and  Eva Heuberger, “The Impact of Natural Odors on Affective States in Humans,” Chemical Senses volume 33, no. 5 (March 18, 2008): accessed December 11, 2018, https://doi.org/10.1093/chemse/bjn011
20. Rachel S. Herz, “Do scents affect people’s moods or work performance?”
21. Marc Schweitzer, Laura Gilpin, and Susan Frampton, “Healing Spaces: Elements of Environmental Design That Make an Impact on Health,” The Journal of Alternative and Complementary Medicine Volume 10, Supplement 1  (2004): S-74, accessed December 11, 2018, https://doi.org/10.1089/acm.2004.10.S-74.
22. J. Lehrner, Christine Eckersberger , P. Walla , G. PoÈtsch, and L. Deecke, “Ambient odor of orange,” 85.
23. Neil Schneiderman, Gail Ironson, and Scott D. Siegel, “STRESS AND HEALTH”.
24. Carol Peckham, “Medscape National Physician Burnout & Depression Report 2018,” Medscape, published January 17, 2018, accessed December 20, 2018, https://www.medscape.com/slideshow/2018-lifestyle-burnout-depression-6009235?faf=1#2.
25. Annick Le Guérer, “Olfaction and Cognition: A Philosphical and Psychoanalyic View” in Olfaction, Taste, and Cognition, ed. Catherine Rouby, Benoist Schaal, Danièle Dubois, Rémi Gervais, and A. Holley, 1st ed., (Cambridge, United Kingdom: Cambridge University Press, 2002), 3.
26. Neil Schneiderman, Gail Ironson, and Scott D. Siegel, “STRESS AND HEALTH”.
27. Ibid.
28. J. Lehrner, Christine Eckersberger , P. Walla , G. PoÈtsch ,and L. Deecke, “Ambient odor of orange,” 83.
29. Egon Peter Köster, “The Specific Characteristics of the Sense of Smell,” 33.
30. Mary-Clare Race, “If hospital environments affect patients, what about their impact on staff,” The Guardian, September 25, 2012.

Bibliography

1. Herz, Rachel S. “Do scents affect people’s moods or work performance?” Scientific American, n.d., accessed December 11, 2018, https://www.scientificamerican.com/article/do-scents-affect-peoples/.
2. Koatz, Ana. “The Smell, that Forgotten Sense,” International Journal of Pulmonary & Respiratory Sciences volume 2, no. 3 (October, 2017): 001-005. https://pdfs.semanticscholar.org/45a2/a81ff8e8d1a82445d853da1a6890123c7f7f.pdf.
3. Kornfeld, Donald S. “The Hospital Environment: Its Impact on the Patient” in Coping with Physical Illness. Current Topics in Mental Health, Boston, MA: Springer, 1977, 237-249, https://doi.org/10.1007/978-1-4684-2256-6_16.
4. Köster, Egon Peter. “The Specific Characteristics of the Sense of Smell,” in Olfaction, Taste, and Cognition, ed. Catherine Rouby, Benoist Schaal, Danièle Dubois, Rémi Gervais, and A. Holley, 1st ed., Cambridge, United Kingdom: Cambridge University Press, 2002.
5. Krusemark, Elizabeth A., Lucas R. Novak, Darren R. Gitelman and Wen Li. “When the Sense of Smell Meets Emotion: Anxiety-State-Dependent Olfactory Processing and Neural Circuitry Adaptation,” Journal of Neuroscience 25, (September, 2013): 15324–15332. https://doi.org/10.1523/JNEUROSCI.1835-13.2013.
6. Le Guérer, Annick. “Olfaction and Cognition: A Philosphical and Psychoanalyic View” in Olfaction, Taste, and Cognition, ed. Catherine Rouby, Benoist Schaal, Danièle Dubois, Rémi Gervais, and A. Holley, 1st ed., Cambridge, United Kingdom: Cambridge University Press, 2002.
7. Lehrner, J. , Christine Eckersberger , P. Walla , G. PoÈtsch ,and L. Deecke. “Ambient odor of orange in a dental office reduces anxiety and improves mood in female patients,” Physiology & Behavior volume 71, (2000): 83-86. https://doi.org/10.1016/S0031-9384(00)00308-5.
8. Naja, Maya, Joël Bree, Judith Lynne Zaichowsky. “The use of ambient scent to improve children’s hospital experience,” Journal of Marketing Trends. 1. (2012): https://www.researchgate.net/publication/283087143_The_use_of_ambient_scent_to_improve_children’s_hospital_experience.
9. Peckham,Carol. “Medscape National Physician Burnout & Depression Report 2018,” Medscape, published January 17, 2018, accessed December 20, 2018, https://www.medscape.com/slideshow/2018-lifestyle-burnout-depression-6009235?faf=1#2.
10. “Psychology And Smell,” Fifth Sense, n.d., accessed December 11, 2018, http://www.fifthsense.org.uk/psychology-and-smell/.
11. Race, Mary-Clare. “If hospital environments affect patients, what about their impact on staff,” The Guardian, September 25, 2012.
12. Schneiderman, Neil, Gail Ironson, and Scott D. Siegel. “STRESS AND HEALTH: Psychological, Behavioral, and Biological Determinants,” Annual review of clinical psychology volume 1, (2005): 607–628. 10.1146/annurev.clinpsy.1.102803.144141.
13. Schweitzer, Marc, Laura Gilpin, and Susan Frampton, “Healing Spaces: Elements of Environmental Design That Make an Impact on Health.” The Journal of Alternative and Complementary Medicine Volume 10, Supplement 1  (2004): S71-83.. https://doi.org/10.1089/acm.2004.10.S-74.
14. Stafford, Tom “Why can smells unlock forgotten memories?” BBC, published March 13, 2012, accessed December 11, 2018 http://www.bbc.com/future/story/20120312-why-can-smells-unlock-memories.
15. Weber Sandra T. , and  Eva Heuberger. “The Impact of Natural Odors on Affective States in Humans,” Chemical Senses volume 33, no. 5 (March 18, 2008): 441–447. https://doi.org/10.1093/chemse/bjn011