Did you know that our sense of smell is the only sense directly tied to the limbic area of the brain; which is considered the emotional control center? This means that when essential oils are inhaled, they go directly to the brain. Our other four senses — taste, sight, touch, and hearing — are first routed through the thalamus before reaching designated areas of the brain. Because the limbic system is directly connected to the parts of the brain that control heart rate, blood pressure, breathing, memory, stress levels, and hormone balance, therapeutic-grade essential oils can have unbelievable physiological and psychological effects.
Each of the essential oils have therapeutic, stimulating, calming, sedative and balancing properties. When we inhale an essential oil molecule, it travels through the nasal passage to a receptor neuron that transports it up to the limbic brain, especially the hypothalamus. The limbic center in your brain is responsible for controlling all the physical, psychological, and emotional responses that your body performs based on the stimulus coming from the outside.
Thus, the ability of essential oils to target your limbic center make them a powerful tool in treating many health ailments. When essential oils are inhaled through the nose, tiny nerves send an immediate signal to the brain and go straight to work on the systems that moderate our minds and bodies. Inhalation can be the most direct delivery method of these incredibly nurturing components in essential oils, since the chemical messengers in the nasal cavity have direct access to the brain.
The limbic area is considered the emotional control center and includes the hippocampus (responsible for long-term memory), amygdala (associated with emotions), hypothalamus (regulates autonomic nervous system and hormones), and cingulate gyrus (regulated blood pressure, heart rate, and attention).
The specific molecules that essential oils are made up of are phenylpropanoids, monoterpenes, and sesquiterpenes. All three of these compounds have unique functions that contribute to the healing properties of essential oils, but sesquiterpenes likely have the greatest effect on the brain for several reasons. Sesquiterpenes can pass the blood-brain barrier. This barrier exists to protect the brain and only very small, lipid soluble molecules can pass; sesquiterpenes are one of those molecules. In fact, because they’re so small, they are capable of penetrating deeply into brain tissue. The fact that sesquiterpenes can cross the blood-brain barrier is particularly important since they’re oxygen carrying molecules. This increase in oxygen helps the brain heal. It can improve learning and concentration, increases energy, and supports the immune system.
In studies performed at Vienna and Berlin Universities, researchers discovered that sesquiterpenes, a natural compound found in essential oils of Vetiver, Patchouli, Cedarwood, Sandalwood, and Frankincense, can increase levels of oxygen in the brain by up to 28 percent (Nasel, 1992). Such an increase in brain oxygen may lead to a heightened level of activity in the hypothalamus and limbic systems of the brain, which can have dramatic effects on not only emotions, but on learning, attitude, and many physical processes of the body such as: immune function, hormone balance, and energy levels. They can also reverse DNA damage and delete it from cellular memory.
Phytochemicals are the healing compound in essential oils. It’s interesting to learn that the very thing that gives an essential oil its characteristic smell is also what provides that oil with its healing ability. There can be hundreds of phytochemicals (plant based chemicals) within each drop of essential oil. Science is just beginning to learn exactly how each phytochemical works in the human body. These phytochemicals have funny names like terpenes, aldehydes, esters, ketones, phenols, oxides, sesquiterpenes, and many more. Each one works differently in the body. For instance, ketones (found in lavender essential oil, patchouli, hyssop) stimulate cell regeneration, liquefy mucous, and have calming properties. Aldehydes (found in lemongrass essential oil, melissa, and citronella) tend to be highly anti-viral and anti-inflammatory.
The Limbic System. Aromatherapy Lifestyle, Quinessence Aromatherapy Ltd 2010. Geoff Lyth
The Effects of Lavender Oil Inhalation on Emotional States, Autonomic Nervous System, and Brain Electrical Activity. J Med Association Thai. 2012 April 95 (4):598-606.