Two-week essential oil inhalation treatment modulates the cortisol awakening response and improves self-reported symptoms in stressed adults

We investigated the impact of the inhalation of a blended essential oil aroma on markers of chronic stress in otherwise healthy adults. The "Stressless™" essential oil blend employed is a proprietary product designed and created by the International Federation of Aromatherapists as a treatment for stress. Seventy-five adults took part in the balanced placebo-controlled design study. Fifty participants with self-reported stress were randomly allocated to undergo two-weeks of an aroma inhalation protocol balanced with two-weeks of perceptible placebo inhalation. A no intervention control group provided data on the variables across the same study period. The dependent variables were the cortisol awakening response (CAR) and subjective measures of stress and associated symptoms assessed at four time points. Data analysis revealed that in stressed individuals exhibiting a suppressed CAR at basal levels, "Stressless™" aromatherapy normalized this physiological parameter to control group levels. However, this modulatory effect was found to be limited to the intervention period and did not show persistence after application. In contrast, the continued improvement in the subjective stress and anxiety scores after the intervention suggested that the effect of aroma on psychological well-being is more resistant. In conclusion, the "Stressless™" essential oil blend may be considered an effective non-invasive tool for stress management in otherwise healthy individuals. These observed effects are discussed within the framework of the regulatory mechanisms of olfaction on the limbic system and the hypothalamic-pituitary-adrenal (HPA) axis.