In our evolution, the sense of smell was the most important of the five senses. We know this by the space that it took up in the archaic brain. As we developed, the other senses were added, but none had the essential element that makes smell so vital for the nervous system – the direct connection with the limbic brain.
As we inhale the fragrant substances, molecules travel through the nose (scent molecules turn into neural transmitters), and affect the brain through a variety of receptor sites in the limbic brain. This is directly connected to control of the heart rate, blood pressure, breathing, memory, stress levels, and hormone balance. The effects are immediate.
As we apply the oil, the molecules also pass through the skin and enter the blood stream, travelling until they find the right cell receptor for binding. For example, a molecule of Rosemary travels to cell receptors on the liver. Finding the right cell receptor, it acts to balance and regenerate this vital organ.
This is down to brain geography. The neural translation of the chemical constituents of the fragrant substance is sent from the amygdala to the hippocampus, a centre for short term memory. Immediately, the smell, emotion, and memory are co-mingled as they are stored in the limbic system. This information then goes on to the hypothalamus for long term memory.
So, imagine you are in a yoga class and you reach a deep state of relaxation and wellbeing. At the same time, you smell the fragrant oil. From then on, every time you smell that oil, your body will be inclined to return to that state of being. It’s not just a reminder, it’s a physiological happening.