Essential oils are known to be very powerful in healing physical, emotional and spiritual imbalances. The effects of essential oils on the psyche is now also shown in a growing amount of clinical research. First, scents have a profound capacity to invoke vivid memories and emotions. These can be both pleasant and unpleasant, as these memories are very personal. Second, and less immediate, are the effects due to the release of neurochemicals. They can range from increased focus and memory to energising, anxiolytic and anti-depressive effects. If you are curious about which essential oils exactly can help, read about the Six essential oils that help when feeling anxious.
Connecting to Emotions and Memory
To explain the first response, the olfactory bulb has direct connections to two brain areas that have important roles in emotion and memory; the amygdala and hippocampus. Unlike the information from all our other senses, signals carried by smell through the nose bypass the thalamus and are processed subconsciously via the cerebral cortex. Specifically, this happens in the piriform cortex which includes the amygdala, known for its primary role in the processing of memory, decision-making and emotions. The olfactory nerves continue from the piriform cortex to the orbitofrontal cortex. Linking with information from other senses and other parts of the limbic system, such as the hippocampus .
Release of Neurochemicals
The more general response is due to the release of neurochemicals that affect mood, and maybe for example invigorating, calming or analgesic. These effects can take up to 20-30 minutes to reach their maximum impact. These responses are induced by inhalation, but also as a result of topical application, or oral intake. These applications of essential oils deliver essential oil constituents to the bloodstream via the lungs, skin or digestive tract. Unlike most drugs and herbal medicines, essential oil molecules are able to bypass the so-called ‘blood-brain barrier’ because of their small size and their solubility profile. Therefore, they enter the brain via the bloodstream as well .
As a side note, we actually have olfactory receptors in our entire body. According to recent research, these highly specialized receptors are found not only in the nose but also in the testis, lung, intestine, skin, heart, and blood. Olfactory receptors are not just about the smell, but they are chemoreceptors, active in all our tissues, with all the promising uses in healthcare yet to be discovered .
Aromas as a Treatment for Anxiety
Many essential oils are known to be effective as a treatment for anxiety and depression. Interestingly, scientific research links depression and anxiety with a change in the ability to smell. It is not uncommon for people who lose their sense of smell, a condition called anosmia, to become depressed. And people with depression and other conditions related to the brain, such as Alzheimer’s, are known to have a reduced sense of smell . The regular smelling of essential oils with smell training improves the ability to smell. It is therefore likely that in fact, all essential oils have some amount of anti-depressant qualities.
Recommended Essential Oils
There are of course a number of essential oils that are particularly suitable to treat anxiety and depression and have clinically proven to have calming, sedative and anti-depressant properties. Professor Paolo Rovesti of Milan University has been a pioneer in research on this topic. He researched combinations of Bergamot, Jasmin, Neroli, Lemon Verbena, Lime, Rose, Violet, Marjoram, Cypress and Petit Grain essential oils, conducted research at a variety of psychiatric clinics and reported great success . Dr T. Miller and G. Mojay, practitioners in naturopathy and clinical aromatherapy presented several essential oils they successfully used as treatments for anxiety at Botanica 2018. They recommend Palo Santo, Ylang Ylang, Vetiver, Lemongrass, Bergamot, Orange, Spike Lavender, True Lavender, Geranium, Rose Otto and Sandalwood, amongst others .
The book, De Neus by Eva Heuberger, Iris Stappen en Regula Rolf von Rohr, gives an in depth explanation of our sense of smell, the link between smell and emotional wellbeing, and practical and effective uses of aromatherapy in clinical settings. Regula Rudolf von Rohr introduced aromatherapy at the university psychiatric clinic (UPK) of Bazel in 1996. In Switzerland, working with essential oils is psychiatry in the last 20 years has become mainstream. The purpose of aromatherapy in this clinical setting is to increase the quality of life of psychiatric patients, in spite of their psychiatric illness or crisis. An important aspect is self-reliance, so patients are increasingly responsible for preparation and application of their treatment. In the book, they highlight the use of essential oils such as Sweet Orange, Angelica, Grapefruit, Tonka, Nardus, Bergamot, and Neroli, amongst others .
Methods of Application
Paolo Rovesti of Milan University sprayed these essences around patients and found them to act as nerve stimulants or sedatives. However direct inhalation is more efficient than indirect ambient inhalation from a diffuser or spray. According to research by N. Singer, using an essential oil blend of Lavender, Mandarin and Vetiver, was significantly more effective as an inhaler than when used as a room spray. In general, the results showed a higher measurable impact on stress-related physiological parameters (heart rate, blood pressure and cortisol levels) and mood. 
In the clinical setting of the university psychiatric clinic (UPK) of Bazel, a variety of applications is used for the patients, depending on their preference and need. Whenever essential oils are applied to the skin at UPK, a blend of a maximum 3% concentration is used. Applications at UPK range from inhalation from a personalised blend in a smell bottle, for everyday themes, to the application with a roller with therapeutic perfume, for multiple applications in the day, application to body parts such as through foot massage, and also foot baths, complete baths, and neck compresses. Lastly, the perception of smell is of great importance, unpleasant odours are simply rejected by the brain and do not gain the same access to the nervous system. Mixtures of essential oils are more pleasant than single oils and are therefore more acceptable . And, of course, the quality of the essential oils used has a great influence on its therapeutic efficacy.
1. E. Heuberger, I. Stappen et al. De Neus, Het orgaan dat veel meer invloed heeft op onze gezondheid dan we denken, 2018.
2. R. Tisserand. How essential oils work in the body: Inhalation and the brain, 2016.
3. Désirée Maßberg and Hanns Hatt, Human Olfactory Receptors: Novel Cellular Functions Outside of the Nose, 2018.
4. K.G. Stiles. The Essential Oils Complete Reference Guide: Over 250 Recipes for Natural Wholesome Aromatherapy, 2017.
5. Dr T. Miller and G. Mojay. Anxiety: Naturopathic and TCM Aromatic Therapeutics, Botanica2018, lecture 3 September, 2018.
6. Komori, T et al. Effects of Citrus fragrance on immune and depressive states, 1995.