Smell.....It's the first sense that's activated when we are born..... and it can instantly transport you back to your grandmother's kitchen or ex-lover's embrace....
And these nostalgic ties aren't just a coincidence - there is a science behind why we cherish these aromas. Our Olfactory response is directly linked to the emotional centre of our brain, causing a flood of warm and fuzzy feelings with a simple sniff. Unlike touch or taste, scents are directly correlated with past experiences.
But aside from their memory inducing powers, certain scents can also do amazing things for our mind and body. From stress relief to headache relief, certain aromas have a way of making an impact (and positively so)
People have used the scents of plants, trees, herbs and fruits since ancient times to fight inflammation, depression and induce sleep.
The Olfactory System
The Olfactory System includes all physical organs or cells relating to or contributing to the sense of smell. When we inhale through the nose, airborne molecules interact with the olfactory organs and almost, immediately to the brain.
Molecules inhaled through the nose of mouth are also carried to the lungs and interact with the respiratory system. Thus inhaled essential oils can affect the body through several system and pathways.
Interaction with the Limbic System (emotional brain)
During inhalation, odor molecules travel through out the nose and affect the brain through a variety of receptor sites, one of which is the limbic system, which is commonly referred to as the "emotional brain".
The limbic system is directly connected to those parts of the brain that control heart rate, blood pressure, breathing, memory, stress levels and hormone balance (Higley & Higley, 1998). This relationship helps explain why smells often trigger emotional. Knowing this, we can hypothesise how inhalation of essential oils can have some very profound physiological and psychological effects.
Source: taking charge.csh.umn.edu - How Do Essential Oils Work