Energise or Unwind: How Essential Oils Shape Stress and Calm in the Body

Our sense of smell has a direct line to the nervous system—capable of stirring energy or softening stress with just a single breath. But how, exactly, do essential oils influence the body on a physiological level? A fascinating study published in the Japanese Journal of Pharmacology sheds light on this question by examining how different fragrances affect sympathetic nervous system activity—the branch responsible for fight, flight, and alertness.

In this 2002 study, researchers S. Haze, K. Sakai, and Y. Gozu exposed healthy adults to a range of essential oils and monitored changes in blood pressure and stress-related biomarkers, including levels of adrenaline. Their findings revealed a clear divide between scents that stimulate and those that soothe.

Essential oils like black pepper, tarragon, fennel, and grapefruit significantly increased sympathetic activity, in some cases by up to 2.5 times compared to an odorless control. These invigorating oils appear to awaken the body, heightening energy and readiness—a response accompanied, in the case of pepper oil, by elevated adrenaline levels.

On the other end of the spectrum, oils like rose and patchouli produced the opposite effect: a reduction in sympathetic activity by as much as 40%, and a measurable drop in adrenaline. These findings support the use of rose and patchouli for stress relief, emotional grounding, and calming the nervous system after periods of tension or overstimulation.

This study not only validates long-standing aromatherapy practices—it also gives us a language for working with scent in a more intentional way. Need focus and energy? Reach for pepper or grapefruit. Seeking rest, stillness, or nervous system support? Inhale rose or patchouli.

Whether you’re crafting a morning ritual or winding down from a high-stress day, essential oils offer more than fragrance—they offer access to the body’s internal rhythms, helping you adjust the dial between energised and at ease.