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IFRA Seminar Audience
It can be scientifically verified that smells affect people’s moods, said Tim Jacob of Cardiff University at a recent International Fragrance Association (IFRA) organized fragrance industry meeting held in Brussels.
“Various scientific studies have shown that lemon fragrances can act as an antidepressant,” said Jacob. “Orange and wood oils decrease stress and so does lavender, which is also associated with happiness. Meanwhile, food and fruit odors help patients recover from illness. So bringing flowers and grapes to hospital really will help sick relatives to get better.”
The use of odors and fragrances could also help with mood and sleep.
“We can take advantage of the behavior of this system to influence mood and physiological state,” said Jacob. “The intrinsic properties of smell can be used to influence mood, and smell can be conditioned to mood.”
For instance, he said, in one experiment mice were given a combination of naphthalene and interferon and conditioned to increase the presence of natural killer cells in their bloodstream, thus strengthening their immune systems. A month later the same mice were presented with the naphthalene odor again without the presence of interferon, but the mice continued to produce the cells. Another study led by Jacob found a link between odors and the ability of subjects to go to sleep. Over a period of several weeks, test subjects exposed to key odors found it increasingly easier to sleep than the control group. In both male and female subjects the level of skin conductance fell, suggesting that they were in a more relaxed state.
On an even more basic level, Jacob argued that the sense of smell helps humans to choose their lovers and mates. People often choose mates who give off a distinctly different odor, which may signal a notably different immune system that in combination can aid in the production of children that are healthier than their parents. In an experiment, Jacob tested out this “hedonic reciprocity,” asking students to anonymously rate the odors of other students—both male and female—as attractive or unattractive. Candidates of similar genetic makeup disliked each others odors, while they enjoyed the smell of those who were dissimilar. “They reciprocally hated and liked the smell of other candidates,” said Jacob.
The sense of smell or lack of it can have other health implications, said Steve van Toller, a pioneer in the field who set up the world’s first olfaction department at the University of Warwick in the 1970s. Patients with anosmia—the loss of the sense of smell often caused by a blow to the front of the head that severs the olfactory nerves—complain that they also lose their sense of taste. The first reported account was made public in the 1860s and focused on the case of a person who lost his sense of smell after falling from his horse in 1837. This example was largely forgotten until research papers on anosmia started to be published again in the 1940s. Toller further explained that patients often feel that their complaint is unique. Part of the treatment of the condition includes reassurance and an investigation of how strong a sense of smell patients used to have.