How & Why Essential Oils Work
by Katy Lamothe, Graduating Apprentice at Anarres
Katy presently offers consultation and Reiki at Anarres Apothecary.

Humans, like all animals, are creatures of survival. Our nervous systems are wired to survive. When the nervous system detects a threat, the options the body has available to survive or re-establish safety, are fight, flight, freeze. These processes are automatic, like reflexes, and do not require thought, reflection or intention, as often when danger is present an immediate response is required for survival. Fight, flight and freeze can all be viewed as acts of self-preservation. These responses function to keep us alive.

How Our Brain Works

Lower brain/limbic system: sometimes referred to as the "lizard brain", this part of the brain is responsible for breathing, emotions, and instinctively assessing situations, as well as signalling to the nervous system how to respond to a threat (fight, flight, freeze). The thalamus, amygdala and hippocampus are part of this system. Humans are born with the limbic system highly developed and it finishes development very early in life, therefore our survival instincts are present from birth.

By Polygon data were generated by Database Center for Life Science(DBCLS)[2]. (Polygon data are from BodyParts3D[1]) [CC BY-SA 2.1 jp (http://creativecommons.org/licenses/by-sa/2.1/jp/deed.en)], via Wikimedia Commons

Front brain/pre-frontal cortex: This is the "human" part of the brain, the part of the brain that separates us from animals. While the lower brain's development is complete when we are born, this part of the brain develops with age and experience. It is responsible for logic, reason, awareness, self-consciousness, communication and regulating emotions. The frontal brain is not fully developed until approximately age 25.

*When children are born, their nervous systems and front brain are far from being fully developed, and they respond highly to the nervous systems of the other humans they are around. During this important time, trauma can inhibit the development of the pre-frontal cortex.

Sounding the alarm: The thalamus formulates a conclusion (ie. someone is chasing me) and sends it to the amygdala and front brain. The amygdala is the alarm centre of the brain and decides if what's happening is a threat or not. The hippocampus brings in past experiences to inform the amygdala's alarm response. The front brain is like the watch tower and through awareness can offer perspective "it appears as if someone is chasing you but it is just reminding you of something that happened before" Information gets to the amygdala faster from the lower brain than it gets there from the front brain so the front brain does not always have time to process the information before the alarm goes off.

Fight or flight response occurs when the amygdala has determined a threat and activates our whole body to respond. The body gets ready to run (flight) or fight. This is an activation response: muscles tense, digestion shuts down in order to preserve energy and flood extremities with blood in order to be ready to move. Senses heighten, breath and heart rate elevates, and adrenaline and cortisol inundate our bodies. We get ready to either run or defend ourselves and our systems are designed to automatically determine which will be the most effective strategy for survival in any given set of threatening circumstances.

Freeze response is a last ditch effort to self-preserve if fight and flight are deemed not suitable for survival. In animals, they collapse and play dead as predators are not interested in dead prey. In humans, this is when our physical systems shut down as a mechanism of dissociation. This occurs when our systems deem fight or flight strategies to be ineffective. Freeze is a deactivation response: systems shut down, muscles become slack, senses become dull. Dissociated from what has been interpreted as imminent threat, and disengaged from ourselves and from feelings of fear, we are less present to experience the inevitable pain and suffering our system has determined we are about to be exposed to. Freeze is like a last ditch effort to survive.

Trauma and Post-Traumatic Stress (PTS)

Trauma occurs when our ability to cope is overwhelmed. Trauma is defined by how events are experienced and internalized, rather than by the event itself. This means that anything could be experienced as trauma.

Trauma always involves the body, even when the traumatic event causes no bodily harm. When we speak of the ability to cope being overwhelmed, we are always speaking about the bodily response of the nervous system, as well as how the nervous system manifests in our body as action or inaction. When we receive stimuli from our environment, it is our body (the brain) which interprets these stimuli and our body which is the tool for mounting an appropriate response. When a threat is interpreted by the nervous system, we rely on the body to respond in a way that re-establishes a sense of safety (fight, flight or freeze). In an integrated response to threats, the lower brain's reflexive interpretation is balanced by a down-flow of information from the front brain, which can incorporate reason, insight and awareness to provide perspective and further inform our responses, heightening our ability to activate a parasympathetic response, as well as restoring calm and a sense of safety.

When we are unable to access this down-flow of information, we are limited to reacting from our limbic system. Without perspective, our ability to gain a sense of safety is limited and our capacity to cope with threat can be overwhelmed. When the nervous systems does not return to a sense of safety we are unable to return to a place of healthy regulation.

Post-traumatic stress (PTS) occurs when we remain stuck in a survival response despite the threat no longer being present. Trauma can be experienced without any long-term debilitating effects when the system restores to a sense of safety. In someone with PTS, these responses keep going even when the threat is gone. If the system doesn't complete itself back to a state of safe and calm, the response stays on.

Someone whose system hasn’t restored from an activation response (fight/flight) may experience: hyperactivity, anxiety/panic, hyper-vigilance, rage, obsession to control, startle easily, lack of ability to communicate clearly, limited capacity for reason/perspective.

Someone whose system hasn’t restored from a shut-down response (freeze) may experience: chronic fatigue, depression, dissociation, dissociation, under-arousal, lethargy, under-reaction, inability to feel pain or respond to real danger, constriction (closed in), lack of ability to communicate clearly, limited capacity for reason/perspective

How can aromatherapy help?

The limbic system is a part of brain that is one of the first to form as a fetus. It is the interface between the brain and the outside world. The limbic system is the seat of the emotional centre and is partly responsible for our fight or flight response, our emotional reaction to something, our hormonal secretions, motivation, pain reflex and our mood fluctuations. There are three main components to the limbic system: the hypothalamus, the hippocampus and the amygdalae, which we discussed above. There are also the pituitary, the cingulate gyrus, the fornicate gyrus, the thalamus, the mammillary body, the nucleus accumbens that help form the system, plus the olfactory bulb that plays such an important part in aromatherapy.

To understand the limbic system we need to break it down into its main constituents. The first part that we will briefly look at is the hypothalamus, which strives to bring the body into homeostasis. If the body is feeling imbalanced, the hypothalamus will try to return it to “set point” much like a thermostat adjusting hot and cold. The hypothalamus regulates hunger, thirst and response to pleasure and pain. It also affects, through the parasympathetic and sympathetic nervous system, one’s blood pressure, heart rate, the sleep/awake response and sexual arousal. Its relationship to the endocrine system allows for hormone production and release.

The hippocampus converts short-term memory into long-term memory and deals with spatial navigation. Interestingly enough, in Alzheimer’s patients, this is one of the first parts of the brain to be affected and if there is damage to this part of the brain, memories prior to the damage are hard to retrieve. In a faulty functioning hippocampus, people somehow forget where they are and how they got there. The hippocampus allows us a sense of direction and a knowing of how to navigate through life both physically and internally.

The amygdalae are primeval arousal centers that process the memory of emotional reactions. They store all information concerning emotional events, which include fear conditioning and conditioning of emotional response. The amygdalae register non-verbal signals of anger, fear, defensiveness and aggression. They also contribute to the sexual response. When input from the olfactory bulb and olfactory cortex arrives at the amygdalae, impulses are sent out to other the parts of the limbic system and the fight or flight response takes over. There is a demand for increased sympathetic nervous response, asking for faster reflexes, an appropriate facial expression and increased hormonal production.

How does all this work?

Let’s say that an aroma fills the room and the smell is inhaled. Odourant molecules infiltrate the nasal passages and travel through to the olfactory epithelium where neurons with cilia bind onto the odourant. Inside the neurons there are protein called odourant receptors. There are thousands of neurons in the epithelial tissue, but in humans we can only pick up smell with about 300 different odourant receptors (dogs have many more). So, the odourant receptors in the neurons bind to an odourant molecule. The receptor cells then convert the proteins into electrical impulses, which travel along the olfactory nerve to the cribiform plate and then to the olfactory bulb. From the olfactory bulbs, odour impulses travel directly to the olfactory cortex in the temporal lobe or to the limbic system (especially the hypothalamus and pituitary).

Aromatherapy can play a big part in stress reduction, balanced heart rate, hunger control and sexual desire, all because of its inter-relationship with the limbic system. Whether the oils are rubbed on in massage oil or inhaled through an aroma lamp, the odour molecules will travel to their limbic destination and create the appropriate neurochemicals to affect a physical response.

When any scent is inhaled, the odour molecules travel up the nose where they are trapped by olfactory membranes. Each odour molecule fits like a little puzzle piece into specific receptor cell sites that line a membrane, known as the olfactory epithelium. When stimulated by odor molecules, this lining of nerve cells triggers electrical impulses to the olfactory bulb in the brain. The olfactory bulb then transmits the impulses to the gustatory center (where the sensation of taste is perceived), the amygdala (where emotional memories are stored), and other parts of the limbic system 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 profound physiological and psychological effects. The sense of smell is the only one of the five senses directly linked to the limbic lobe of the brain, our emotional control center.

Scent stimulates nerves to fire in the emotional center of the brain, but it also stimulates the master gland to release hormones. Hormones affect the fight or flight response, as well as digestion and heart rate. In this way, essential oils can affect us in many ways all at once, just through their fragrance.

Anxiety, depression, fear, anger, and joy all emanate from this region. The scent of a special fragrance can evoke memories and emotions before we are even consciously aware of it. When smells are concerned, we react first and think later. All other senses (touch, taste, hearing, and sight) are routed through the thalamus, which acts as the switchboard for the brain, passing stimuli onto the cerebral cortex (the conscious thought centre) and other parts of the brain.

The limbic lobe (a group of brain structures that includes the hippocampus and amygdala located below the cerebral cortex) can also directly activate the hypothalamus. The hypothalamus is one of the most important parts of the brain, acting as our hormonal control centre. It releases chemical messengers that can affect everything from sex drive to energy levels.

The production of growth hormones, sex hormones, thyroid hormones, and neurotransmitters such as serotonin, are all governed by the hypothalamus. Thus, the hypothalamus is referred to as the “master gland.” Essential oils–through their fragrance and unique molecular structure–can directly stimulate the limbic lobe and the hypothalamus.

Katy presently offers consultation and Reiki at Anarres Apothecary.

All Rights Reserved 2015, copyright by author by Katy Lamothe, Graduating Apprentice at Anarres. Please write for permission to reproduce any part of this post.