Experts think aromatherapy activates areas in your nose called smell receptors, which send messages through your nervous system to your brain.
The oils may activate certain areas of your brain, like your limbic system, which plays a role in your emotions. They could also have an impact on your hypothalamus, which may respond to the oil by creating feel-good brain chemicals.
Some experts think that when you put essential oils on your skin, they cause a response in your skin and other parts of your body, like your joints.