Kerala AWC Foster City
Aroma: The Forgotten Mover
With so many external stimuli in life, it is easy to overlook our sense of smell. Many people complain that they have a poor sense of smell. However, there is a difference between conscious awareness of smell and subconscious reaction to aroma.
As humans, our sense of smell is one of the primary modes through which we engage the external world. From sniffing food for freshness in the grocery store to reconnecting with our past through a long forgotten scent to savoring the perfume of a potential mate, we are consciously and subconsciously driven by our sense of smell.
In her book, A Natural History of the Senses, Diane Ackerman reminds us that smell is one of our primary methods of discrimination. "Meat eaters smell different from vegetarians, children smell different from adults, smokers smell different from non-smokers; other individuals smell different because of hereditary factors, health, occupation, diet, medication, emotional state, even mood." Our sense of smell guides us and grounds us in our lives.
It has been said that just as the eyes are the window to the soul, the nose is the gateway to the mind. Even undetected aroma can induce unpredicted reactions, mood changes, alertness, arousal, or agitation. Though subtle, our sense of smell has a powerful impact on our being.
The notion that aroma can affect our emotions, mood, and memory is not only affirmed by folklore, but it is also supported by scientific study. The causal reason for the effects of aroma may be debated, but it is acknowledged that the olfactory bulb, which is responsible for sense of smell, is in the same neuro-functional system as the hypothalamus, which affects hunger, thirst, sexual arousal, and the sleep-wake cycle; the nucleus accumbens, which is involved in feeling pleasure, aggression, and fear; the dentate gyrus, which is thought to play a role in happiness and depression; and the hippocampus, which is involved in the formation of long-term memories. By the interconnectivity of these functional areas within the limbic system, it stands to reason that a substance which affects the olfactory bulb would also affect the other areas of the limbic system and their functional activity. Therefore, through stimulation of the olfactory bulb, aroma can affect our emotions, behavior, and long term memory.
The notion of using scent to affect the emotions and mood has become very popular, and often the first things that come to mind are pheromones. We have all heard of using pheromones to make us more attractive. Some believe and some don’t, but German biochemist Peter Karlson and Swiss entomologist Martin Lüscher coined the term “pheromone” in 1959 after observing that a termite will indeed respond to aromatic chemicals released by other termites around it. They demonstrated that this scent transmission influenced behavior of other insects and served as a form of communication.
Pheromones affect mammals too. A pig pheromone called androstenone “turns a sows attention to mating and nothing else, and induces her to assume the sexually ready position” (Herz 2009). Today, there is even a commercially available spray called “Boar-Mate,” which contains androstenone. Some farmers use this spray to facilitate the process of artificial insemination of their sows. Of course, perfume and cologne makers desperately seek human pheromones which could have a similar effect on humans!
Pheromones have been observed to affect humans in other aspects of life, however. Martha McClintock documented, as many women have observed, that women living together seem to synchronize their menstrual cycles. Beyond this effect, little is revealed in the literature about a pheromone that drives people wild. On the contrary, McClintock remains skeptical that "a particular product will increase the user's opportunities for sexual intercourse regardless of context"
From the neurochemical perspective, pheromones can have an odor or be odorless and are active on a structure called the vomeronasal organ (VNO). The VNO connects to the accessory olfactory bulb. The VNO is technically not directly linked to the olfactory system; it is located above the roof of the mouth, rather than in the brain. Despite its indirect connection, it has a powerful effect on behavior.
More direct connections have been shown between aroma and mood. Researchers from the University of Miami School of Medicine and Duke University Medical School have shown that aroma molecules directly affect behavior, physiology, and mood. In a study of 40 subjects, Diego, et. al. evaluated the effects of lavender and rosemary aromas on mood and mental acuity as measured by EEG and math computation challenges. Lavender was hypothesized to be a relaxing odor, and rosemary was hypothesized to be a stimulating odor. EEG brainwave, computation tests, and survey of test subjects confirmed better relaxation and increased math computation accuracy with lavender and improved alertness with rosemary.
In Japan, the effects of aroma on the psyche have been put to practical use. Termed "Aromacology," health clubs, malls, and office buildings have attempted to augment their experience with aroma. In Tokyo, a health club offered 30 minute, stress-relieving, aroma cocktail sessions. A mall hosted phone booths with aroma-releasing atomizers. The Kajima Corporation even went to the effort of installing a "Total Environment Perfume Control System" to refresh, stimulate, and aid the concentration of its office workers at scheduled times of day.
Van der Watt and Janca from the School of Psychiatry and Clinical Neurosciences at the University of Western Australia have gone on to study the efficacy of aromatherapy in treating anxiety, depression, and stress. Compelled by the dearth of definitive sources, this research team has published a broad-based clinical literature review. In it they reference the randomized control trial of 100 post-cardiac surgery patients conducted by Stevensen in 1994. In the study, Stevensen concluded that neroli oil reduced anxiety in this patient series.
Another study by Perry and Perry (2006) found lavender or lemon balm compared favorably with antipsychotic drugs for treatment of agitation in dementia. These authors also reviewed the use of bergamot and geranium in treating depression, but their study suffers from a lack of methodological rigor. The historic lack of rigor is recognized by the clinical community, but future research by Hongratanaworakit & Buchbauer is expected to adequately document the effects of ylang ylang on reducing blood pressure and symptoms of depression.
While many essential oils remain to be studied, robust data have been generated in the study of peppermint and cinnamon odors. Raudenbush, et. al. studied the effects of odor on athletic performance and found, in their 2001 and 2002 studies, that athletes exposed to peppermint scent were able to run faster, do more push-ups, and demonstrate greater grip strength.
With such clear results, it was hypothesized that peppermint, and also cinnamon, could possibly improve alertness and performance while driving. 100,000 annual car crashes and 1,500 annual auto fatalities are definitely enough to warrant investigation of methods to improve driving safety.
In Raudenbush, et. al.'s 2009 study, 25 adults with a mean driving experience of 3.4 years, were exposed to aerated peppermint oil, cinnamon oil, or a non-scented control and asked to drive through a fixed course on a virtual reality driving simulator. Qualitative assessments of mental demand (NASA-Task Load Index), mood (Profile of Mood States), and alertness were recorded. The results revealed that both peppermint and cinnamon improved alertness and reduced frustration. Peppermint also reduced anxiety and fatigue.
Clearly, it is demonstrated and popularly believed that scent can affect mood, impulses, and urges, but scent has also been shown to have many other effects as well. In 2004, Raudenbush, et. al. extended their body of work through investigation of the effects of scent on pain tolerance. In this study entitled "Effects of Odorant Administration on Pain and Psychophysiological Measures in Humans," 158 subjects were exposed to either low-flow oxygen, oxygen plus peppermint odor, or oxygen plus jasmine odor while holding their dominant hand and forearm submerged in a 3°C water bath for 5 minutes. Pain was rated by the subject every 30 seconds. Blood oxygen saturation was measured to quantify inhalant uptake. Mood (POMS), workload (NASA-TLX), and anxiety (STAI) were measured through qualitative questionnaires.
Results showed that both peppermint and jasmine statistically significantly increased pain tolerance and reduced physiological stress versus the control. Statistical differences between the effects of peppermint and jasmine were muddled by the standard deviation of the data. It is not clear whether the peppermint and jasmine scents had a physiological affect or whether they simply distracted the subject from the pain. However, it is clear that the scents helped the subjects to relax despite painful stimulus.
The ability to use scent to alter mood can have a profound impact on day-to-day life experiences. Many people use scented candles or oils to set a desired mood, and even retail marketers have come to value the power of scent. Perfume makers and product marketers have moved beyond basic aromas and essential oils, and now use scientifically characterized scents to affect mind, mood, and health.
With such growing popularity in scent science, the annual International Symposium of Aromatherapy and Medicinal Plants is now in its twelfth year
The mood map shows the ratings of clementine and vanilla bean in eight different categories, and it shows a composite position on the axes of mood and arousal. What is fascinating about the mood map and about the scientific studies of various aromas is that people respond consistently to each scent. Peppermint is stimulating. Lavender is relaxing. This consistency of response exposes the commonality of the human sense of smell.
Ayurveda describes smell as one of the five causal elements (tanmatras). It is rooted in the element (mahabhuta) earth. Of course, the sense organ (gyanendriya) associated with smell is the nose. The body's organ of action (karmendriya) capable of producing smell is the anus. The connection between the nose and anus makes sense especially in the context of Ackerman's commentary that "Meat eaters smell different from vegetarians, children smell different from adults...." These differences are most readily observed through anal effluent, however sweat and scent glands are also responsible for an individual's personal odor.
The commonality of scent and the way in which we experience it is what makes it possible for the new wave of retailers to “to change mental disposition and put us in a “shopping mood”. The company ScentAir produces seductive scents for companies like Sony and a bedding store called Select Comfort to encourage spending. Use of scent is especially powerful in the retail setting because shopping is primarily an emotional process rather than an intellectual one. By soothing a shopper into an emotionally compliant mood, the retailer can seduce the shopper into making a purchase.
Aroma can seduce, relax, stimulate, or alter our experience of the present moment in numerous ways. It also has the power to take us back in time to the past. Whether it is the smell of charcoal reminding us of summer barbecues or fresh baked sweet smells taking us home to our mother's kitchen, aroma can transport us to another time and place. Most often, we experience memorable scents by accident, but we can also affect our consciousness through purposeful use of aroma.
Because aroma can alter emotions and stimulate memories, it can be used to alter the disposition of the mind, body, and soul. From the Ayurvedic perspective, aromatherapy is the use of scent to stimulate and balance doshic energies. Typically, the scents used in aromatherapy are from plant derived essential oils. Various combustible minerals are also used.
In practice, aroma is released from essential oil heated in an oil burner or oil lamp. Aromas can also be delivered to an environment by burning a scented candle, smoking herbs, from potpourri, or with a nebulizer.
Below are recommended aromas from the Kerala Ayurveda Academy Swastha Vritta text for pacifying Vata, Pitta, and Kapha doshas:
To balance Vata, use calming and pacifying aromas: basil, orange, geranium, clove, rose. These aromas have the added benefit of calming restlessness and anxiety, promoting sleep, and stabilizing metabolism.
To balance Pitta, use cooling and sweet aromas: sandalwood, mint, rose, jasmine, khas, vetiver. These aromas also reduce irritability, anger, and jealousy, and they improve digestion.
To balance Kapha, use stimulating, spicy aromas: juniper, ginger, eucalyptus, camphor, clove, saffron. These aromas also reduce blockages, fat, and water retention, and they stimulate metabolism.
Aromatherapy can be used in everyday life and to balance seasonal or environmental energies. Although recommended to balance Kapha, stimulating aromas can also be used in the office to aid productivity. Cooling aromas typically recommended for Pitta can be used to cool oneself down on a hot summer day. Calming aromas can be used at the end of a stressful work day just to help oneself relax and to settle down for sleep.
Thus scientific research and common knowledge of the human experience affirm that aromatherapy is an effective tool whether used for Ayurvedic healing, marketing, or just daily living. Our sense of smell is a basic aspect of life and fundamental to the way we have come to know ourselves as human. Aromatherapy is central to that experience and is shown to be an essential element of a healthy, balanced life.
Appendix: In Depth Olfactory Anatomy
(from cited resources)
The Olfactory System
The olfactory system consists of the olfactory epithelium, bulbs and tracts along with olfactory areas of the brain collectively known as the rhinencephalon.
Sensory Transduction and Peripheral Course of the Olfactory Nerve Inhaled aromatic molecules dissolve in the moisture lining the olfactory epithelium and stimulate its chemoreceptors. Olfactory receptor cells initiate action potentials in response to these chemical stimuli. Intracellular studies show the presence of a slow rising receptor (generator) potential followed by a spike discharge from the receptor cell. The peripheral processes of the receptor cells assemble into small bundles and pass through the cribiform plate of the ethmoid bone to synapse on secondary sensory neurons in the olfactory bulb.
The olfactory region consists of cilia projecting down out of the olfactory epithelium into a layer of mucous which is about 60 microns thick. This mucous layer is a lipid-rich secretion that bathes the surface of the receptors at the epithelium surface. The mucous layer is produced by the Bowman’s glands which reside in the olfactory epithelium. The mucous lipids assist in transporting the odorant molecules as only volatile materials that are soluble in the mucous can interact with the olfactory receptors and produce the signals that our brain interprets as odor. Each olfactory receptor neuron has 8-20 cilia that are whip-like extensions 30-200 microns in length. The olfactory cilia are the sites where molecular reception with the odorant occurs and sensory transduction (i.e., transmission) starts.
Above the mucous layer is the base olfactory epithelium which consists partially of basal cells located in the lowest cellular layer of the olfactory epithelium which are capable of mitotic cell division to form olfactory receptor neurons when functionally mature. The olfactory receptor neurons turnover approximately every 40 days. The epithelium also contains pigmented cells that are light yellow in humans and dark yellow to brown in dogs. The depth of color seems to be correlated with olfactory sensitivity.
While the olfactory receptor neurons extend through the epithelium to contact odorants in the atmosphere, on the opposite side within the epithelium, the neuronal cells form axons that are bundled in groups of 10-100 to penetrate the ethmoidal cribiform plate of bone, reaching the olfactory bulb of the brain where they converge to terminate with post-synaptic cells to form synaptic structures called glomeruli. The glomeruli are connected in groups that converge into mitral cells. (Note that in the picture this convergence is not clearly depicted). For example, in rabbits, there are 26,000 receptor neurons converging onto 200 glomeruli which then converge at 25:1 onto each mitral cell. The total convergence is estimated to be about 1000:1.
Physiologically, this convergence increases the sensitivity of the olfactory signal sent to the brain. From the mitral cells the message is sent directly to the higher levels of the central nervous system in the corticomedial amygdala portion of the brain (via the olfactory nerve tract) where the signaling process is decoded and olfactory interpretation and response occurs.
Ackerman, Diane. A Natural History of the Senses. New York: Vintage Books, 1990.
"Aromacology: The Psychic Effects of Fragrances." The Futurist. Sep.-Oct. 1990: 49-50.
Caplan, Jeremy. "Scents and Sensibility." Time. 16 Oct. 2006: Vol. 168, Issue 16, 66-67.
Diego, Miguel, et. al. "Aromatherapy Positively Affects Mood, EEG Patterns of Alertness and Math Computations." International Journal of Neuroscience. 1998: 96; 217-224.
Herz, Rachel. "The Truth about Pheromones: Part 1." Psychology Today. 18 May 2009.
Herz, Rachel. "The Truth about Pheromones: Part 2." Psychology Today. 18 June 2009.
"KAA 105: Swastha Vritta." Foster City: Kerala Ayurveda Academy, 2009.
Raudenbush, Bryan and Koon, Jerrod. "Effects of Odorant Administration on Pain and Psychophysiological Measures in Humans." North American Journal of Psychology. 2004: Vol. 6, No. 3, 361-370.
Raudenbush, Bryan, et. al. "Effects of Peppermint and Cinnamon Odor
Administration on Simulated Driving Alertness,
Mood and Workload." North American Journal of Psychology. 2009: Vol. 11, No. 2, 245-256.
Van der Watt, Gillian and Janca, Aleksandar. "Aromatherapy in Nursing and Mental Health Care." Contemporary Nurse. Aug. 2008: 30; 69-75.
Warrenburg, Stephen. "Effects of Fragrance on Emotions: Moods and Physiology." Chemical Senses. 2005: 30 (supplement 1); i248-i249.
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