Evaluation of Aromatic Essential Oils in Conditions of Stress and Relaxation - A Double-Blind, Randomized, Placebo-Controlled Trial
Evaluation of Aromatic Essential Oils in Conditions of Stress and Relaxation - A Double-Blind, Randomized, Placebo-Controlled Trial
This randomized, double-blind, placebo-controlled study evaluates the acute physiological and subjective responses to essential oil inhalation in healthy adults. Participants are assigned to inhale either an essential oil or a placebo via an aroma stick during standardized laboratory procedures designed to induce temporary psychosocial stress (Trier Social Stress Test - Group version) and during a guided relaxation session.
Physiological responses, including heart rate, heart rate variability, and electrodermal activity, are measured using a wearable sensor. Subjective stress and affect are assessed using validated questionnaires and visual analog scales. The purpose of this study is to characterize short-term autonomic and self-reported responses associated with essential oil inhalation under controlled experimental conditions. This study is exploratory and is not intended to diagnose, treat, or prevent any medical condition.
Essential oils and essential oil blends are widely used in non-clinical settings; however, objective data describing short-term physiological and subjective responses to inhalation under controlled experimental conditions remain limited. This study is designed to evaluate acute autonomic and self-reported responses to essential oil inhalation during standardized laboratory procedures involving psychosocial stress and guided relaxation.
This is a randomized, double-blind, placebo-controlled, parallel-group study conducted in healthy adults aged 18-45 years. Participants are assigned to inhale either an essential oil (or essential oil blend) or a placebo comparator administered via an identical aroma stick. Inhalation occurs at standardized time points during two study visits.
During Study Visit 1, participants undergo the Trier Social Stress Test - Group version (TSST-G), a validated laboratory paradigm designed to induce temporary psychosocial stress through public speaking and mental arithmetic tasks performed under observation. Inhalation occurs during baseline, preparation, stress, and recovery phases. During Study Visit 2, participants undergo a structured guided meditation session under controlled environmental conditions, with inhalation occurring at standardized intervals.
Physiological measures are collected continuously using a wrist-worn wearable device capable of measuring heart rate, heart rate variability (HRV), and electrodermal activity (EDA). Subjective responses are assessed using validated instruments including visual analog scales for stress and calm, PROMIS Anxiety, GAD-7, and PANAS. The primary outcome is change in stress response as measured by area under the curve (AUC) for visual analog scale stress scores across the stress and recovery period.
The study employs an adaptive design with an initial planned enrollment of 100 participants (50 per arm) and a prespecified interim analysis for potential expansion to a maximum of 200 participants. Statistical analyses include comparison of stress and physiological responses between groups using baseline-adjusted models.
This study is exploratory in nature and is intended to characterize acute responses associated with essential oil inhalation under controlled conditions. It is not designed to diagnose, treat, mitigate, or prevent any disease or medical condition.
Inclusion Criteria:
Age 18-45 years, inclusive
Able to read, write, and understand English
Willing and able to provide informed consent
Willing to attend two in-person study visits
Generally healthy, as determined by medical history and screening review
Exclusion Criteria:
Known asthma, chronic obstructive pulmonary disease (COPD), significant lung disease, heart disease, or other medical condition that may compromise safety or data integrity
Pregnancy or pregnancy within the past 90 days
Known allergy or sensitivity to essential oils or study placebo materials
Current smoking, vaping, chewing tobacco, or use of recreational drugs
Regular use of essential oils applicable to the study phase (>3 times per week for ≥2 weeks within the past month) without a minimum 1-month washout
Unwillingness to abstain from alcohol for at least 72 hours prior to each study visit
Failure to meet inclusion criteria