Some Research on Olfactory Benefits of Aromatherapy

by Jade Shutes

Research and Our Sense of Smell

The sense of smell is truly a wondrous sense, a sense which is often underutilized within our modern culture however the growing popularity of aromatherapy is perhaps bringing with it the awareness of this incredible sense. According to the Sense of Smell Institute, as we enter the 21st century fragrance (aromas) will be more than a glamorous fashion accessory or statement of personal style, it will be routinely used to: promote relaxation and reduce stress, improve work performance, elevate mood and reduce depression, modify sleep and dreams, enhance self image, retrieve memories, enhance sexuality, and improve social relationships.

One study showed that the inhalation of lavender (Lavandula angustifolia) is capable of reducing sympathetic nervous activity and decrease blood pressure while the inhalation of Rosemary (Rosmarinus officinalis) is capable of increasing sympathetic nervous activity and provides mental/psychological refreshment. According to Haze et al., it has been reported that human endocrine and immune systems are affected by fragrance. Haze et al. were able to show that the inhalation of black pepper (Piper nigrum), fennel (Foeniculum vulgare) and grapefruit (Citrus paradisi) stimulated sympathetic activity while rose (Rosa damascena) and patchouli (Pogostemum patchouli) decreased sympathetic activity. Black pepper actually increased adrenaline concentration while rose essential oil decreased adrenaline levels. Their results suggest that fragrance inhalation affects the adrenal system via the sympathetic nervous system.


Essential oils are also capable of affecting autonomic nervous system activity via dermal application as revealed in a study by Hongratanaworakit and Buchbauer (2007). The study was performed with 39 healthy volunteers and utilized breathing masks to prevent the inhalation of the aroma of sweet orange (Citrus sinensis). The essential oil was diluted to 1% in sweet almond oil and applied to the skin of the lower abdomen. The study revealed that the transdermal absorption of sweet orange essential oil led to a significant decrease in autonomic nervous system activity (reduced pulse rate, decreased breathing rate) and led to changes in subjective mood, specifically, transdermal sweet orange improved mood and energy of test subjects. The researchers believe that this study supports the application of aromatherapy for the relief of depression and stress in humans.

Other research has shown that inhalation of: ylang ylang (Cananga odorata) is capable of decreasing autonomic nervous system activity ; Lavandula burnatii essential oil vapor may relieve the mood fluctuations of menopausal syndrome by potentially decreasing LH (Luteinizing hormone) and Adrenocorticotropic hormone (ACTH) and restoring catecholamine levels. Angelica essential oil was found to exhibit anxiolytics-like effects similar to diazepam. Lemon essential oil can induce significant, at times sex-specific, changes in neuronal circuits involved in anxiety and pain. The above research extracts represent just some of the wealth of research currently being conducted on the effects of essential oils on the nervous and endocrine systems. We will now explore the anatomy and physiology of these two systems.


Several studies support Horrigan’s observations. In a study on the effect of aroma inhalation on the stress responses of nursing students, it was concluded that the administration of aroma inhalation to nursing students decreased their physical symptoms of stress, lowered anxiety scores, and altered their perceived stress scores. The study concluded that aromatherapy via inhalation could be a very effective stress management method.

Aromatherapy massage affected the autonomic nervous system and thereby induced relaxation. A study designed to evaluate aromatherapy massage and its ability to reduce job-related stress, concluded that there is a positive effect on a statistical significant level of aromatherapy massage reducing work-related stress.

Research on essential oils and work related stress made some valuable points which included the following: The results of the study indicate that essential oils do have the ability to help reduce stress levels in the workplace, but only if certain conditions are met. Aromatherapy is only effective if the essential oils used are suited to the individual benefiting from them. A negative emotional or physical reaction will contribute to stress, as opposed to relieving it. Similarly, the method in which the essential oils are applied can affect the desired outcomes. If a person is not comfortable with the method, it can ultimately increase the stress level. Sweet orange demonstrates stress relieving activity by decreasing cortisol in saliva samples.


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