This is a very general explanation of how essential oils work. I wont be going into the chemistry that heavily. Maybe that will be a future post.
According to Essential Oils Pocket Reference Guide-
"Essential oils have the unique ability to penetrate the cell membranes and travel throughout the blood and tissues."
The smell of essential oils seems to have a powerful effect on our limbic system. Because 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, essential oils can have profound effects on our well-being.
Essential oils can provide inhospitable environments for bacteria and viruses and boost your since of well-being. But don't just take my word on this. Here are some research articles -
Disclaimer: None of these health benefits have been evaluated or approved by the FDA. They are not intended to diagnose, treat, cure or prevent any disease.