Effects of selected volatile oils in Thailand on physiological activities and emotions
Authors:   , Nuiden Nida 
Published: September 2023

The effects of aromatherapy especially essential oil inhalation are believed to be almost instantaneous on physiological and emotional effects but clinical research on the effects of the essential oil inhalation on ANS parameters, brain wave activities and emotional states are still limited. So, this study aimed to examine the physiological and emotional effects of essential oil inhalation namely Cinnamonum porrectum oil, Michelia alba oil, Litsea cubeba oil and one carrier oil as sweet almond oil using scientific techniques on autonomic nervous system (ANS), brain wave activities, and self-evaluated questionnaire on emotional states. This research was an experimental study using A-B design. Individuals who volunteered to participate in this study submitted a written consent form before participating in the study. One hundred as a total number of male and female participants, aged between 20 and 35 years were recruited and divided into 4 groups (25 participants in each group). ANS parameters including systolic, diastolic blood pressures, heart rate, respiratory rate and skin temperature were recorded. EEG was used to record brain wave activities and the questionnaires on emotional states measured feelings of the participants. Data were analysed using paired sample t-test and Wilcoxon match paired sign rank test by STATA. A p-value <0.05 was considered significant. Regarding effects between each oil and sweet almond oil, the results showed that there were no significant changes in ANS parameters, emotional states and brain wave activities between the first inhalation and the second inhalation of sweet almond oil. After the C. porrectum essential oil inhalation, the systolic, diastolic blood pressures, heart rate and respiratory rate increased significantly. The scores of active and fresh feelings increased significantly. The band power of alpha brainwave in left and right anterior as well as center and left posterior increased significantly. After the M. alba essential oil inhalation, the diastolic blood pressure increased significantly. The scores of active and fresh feelings increased significantly but the scores of drowsy feelings decreased significantly. The band power of alpha in left anterior, center, left posterior and right posterior increased significantly but the right anterior decreased significantly. After the L. cubeba essential oil inhalation, the systolic, diastolic blood pressures, the heart rate and the respiratory rate decreased significantly. The scores of good, active, fresh and relaxed feelings increased significantly but the scores of drowsy and stressed feelings decreased significantly. The band power of alpha in right anterior, center, left posterior and right posterior increased significantly. The band power of beta in left anterior, center, left posterior, right posterior increased significantly. The results revealed that the sweet almond oil could be used as carrier oil for essential oil dilution because it did not induce any significant changes. The inhalation of C. porrectum essential oil, M. alba essential oil and L. cubeba essential oil could induce the stimulating effects on autonomic nervous system, positive states of emotion and relaxation of brain states. This study has provided substantial evidence of essential oil inhalation in complementary to well-being and aromatherapy.