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Biology 103
2002 Second Paper
On Serendip

Aromatherapy: Why it makes 'scents'

Stephanie Lane

In countries around the globe, scented oils have been used as medicines for thousands of years, varying in its therapeutic values and uses. Ancient Egypt often used scented oils for their therepuetic effects as different types of medicines, for ailments or diseases (1). In more recent times, scented candles have bombarded the market claiming remedial benefits on mood and cognition. And in institutions for medical practice in clinical aromatherapy can be found in places around the world. But while the interest in aromatherapy has heightened over the years, so has the skepticism surrounding the practice. Product claims to alter health or provide cures have only contributed to the cynicism. Though, individually, a products? capability to enhance a person?s state or mood is debatable, the fundamental theory linking mood to distinct scents is in fact a viable speculation. Underneath the commercialized hype lies scientific data supporting a correlation between scents and mood. A number of recent studies relating to the topic imply the presence of a link and further investigate the olfactory sense and its specific stimulation in the brain. At its most basic level, aromatherapy can effectively be used to alter moods or states.
The process of scent stimulation begins when the molecular chemicals which make up a scent are inhaled through a person?s nose. After traveling through the nasal passage they reach cillia, hair-like fibers connected to the olfactory epithelium, a highly concentrated area of neurons that can send messages to the brain. When the molecule binds to the cillia, the neurons are prompted and send an axon to the brain which processes the perception of smell in what is known as the olfactory bulb, located in a region behind the nose (2).

"Humans can distinguish more than 10,000 different smells (odorants), which are detected by specialized olfactory receptor neurons lining the nose.... It is thought that there are hundreds of different olfactory receptors, each encoded by a different gene and each recognizing different odorants" (3).

The process that occurs after the scent ?reaches? the brain has yet to be fully understood but it seems that the message transmitted to the olfactory system when a scent is smelled is not the only region of the brain that receives it. In one study, anxiety of patients undergoing an MRI was observed. When patients were submerged in a vanilla-like scent, a 63% of the patients showed a reduction in anxiety (4). In another study, it was found that spiced apple and powder-fresh scents ?improved performance on a high-stress task,? (4). In an Austrian study, the effects of a citrus or orange scent in the waiting room of a dental office was studied. While patients were waiting to for dental treatment, they were immersed in an orange smell. It was found that the odor had a relaxant effect, mostly on women. A lower level of anxiety, a more positive mood and a greater sense of calmness were discovered to be direct effects of the orange odor, in comparison to the control group (5).
Many businesses have even subscribed to the idea of altered mood or state through specific scents and used it to increase production. A Japanese company which began using, what was dubbed, ?environmental fragrancing? in which air-conditioning ducts released various therepuetic scents every six minutes to improve alertness or relieve stress. It was found that the introduction of a lemon scent reduced keyboard errors by 50% (4).
While these studies show the effects of specific types of scents and their link to mood, a link as also been determined between scents and their degree of pleasantness on an individual basis and their capability of altering mood. In one such study, habitual smokers were given a variety of different scents to rate on a scale of pleasantness. After being nicotine-deprived for a significant amount of time, the smokers were given the scents and the effect on their craving was observed. It was concluded that the cravings diminished when a non-neutral odor was smelled. Particularly, those odors which the smoker had rated as ?unpleasant? decreased cravings the most (6).
In another related study, observations were made on the heart rate of patients who inhaled unpleasant scents. It was determined that heart rate was increased when the patients inhaled unpleasant scents or were asked to rate them (7). This study serves as support for the theory that the olfactory system first rates a perceived scent on a scale of pleasantness. In conjunction with the other studies, it could be assumed that individual ratings of ?plesantness? vary on an individual basis and may even be culturally derived. The effects of vanilla, for instance, seem to be varied among cultures:

"When Americans smell a strong odor, it seems to remind them of their animality or mortality. On the other hand, vanilla is known to be comforting to Americans, but has no particular effect on Japanese. This may be because it is an unfamiliar smell and therefore has no link to the granny's kitchen of their childhood" (4).

Consequently, a connection between memory or past experience may also influence the degree of personal pleasantness of certain smells.
Through the various studies concerning the correlation between scents and their trigger in other regions of the brain, it can be seen that there is in fact a link. The findings of ?universal? (perhaps limited culturally) mood triggering scents gives further implications of the olfactory system?s connection with other parts of the human brain. The idea of using scents as a means of altering mood or state of mind is valid. Evidence suggests that aromatherapy is a well-founded science and one in need of even deeper investigation. Perhaps scents and their specific associations could be used on a greater scale in the future, to increase productivity, improve mood or just enhance well-being. It seems that this age-old science often waved off as ?phony? has a very scientific base. When a greater understanding of the brain and its related regions is attained, perhaps the science will, once again, become more widely accepted.


1)Perfumes in Ancient Egypt

2)The Sense of Smell

3)How does smell work?

4)The Role of Smell in Language Learning

5)Ambient Odor of Orange in Dental Office Reduces Anxiety and Improves Mood in Female Patients

6)Effects of Olfactory Stimuli on Urge Reduction in Smokers

7)Influence of affective and cognitive judgments on autonomic parameters during inhalation of pleasant and unpleasant odors in humans

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