Effects of Inhaling Essential Oil on Decreasing Mental Fatigue:

Physiological Indices Study, A · 2019 · Crossref

DOI: 10.54941/ahfe100230

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Summary

This study investigates the efficacy of inhaling essential oil in reducing mental fatigue, addressing the lack of objective physiological data to support subjective claims regarding aromatherapy. Mental stress and fatigue in workplace settings are significant contributors to human error and accidents, yet previous evaluations of fragrance therapies have relied heavily on self-reported questionnaires, which are often challenged for their reliability. To provide a more rigorous assessment, this research utilizes electroencephalogram (EEG) and heart rate variability (HRV) indices as objective measures of drowsiness, relaxation, and mental workload. The experimental design involved twenty university students (aged 20–25) divided into an experimental group, which inhaled bitter orange essential oil, and a control group, which inhaled pure air as a placebo. Participants underwent baseline measurements of EEG and HRV, followed by four hours of school courses to induce mental fatigue. Immediately after the courses, and again after a 15-minute inhalation period, physiological data were collected. Subjective workload was assessed using the NASA-Task Load Index (TLX). EEG data were analyzed for delta, theta, alpha, and beta power bands, while HRV analysis focused on low-frequency (LF), high-frequency (HF), and LF/HF ratios to evaluate autonomic nervous system activity. The results demonstrated that inhaling essential oil significantly reduced mental fatigue compared to the placebo. In the experimental group, EEG ratio indices $(\alpha+\theta)/\beta$ decreased and $\theta/\alpha$ increased, indicating a shift toward relaxation and reduced drowsiness. Specifically, the $\beta/\alpha$ ratio decreased significantly, reflecting improved alertness relative to the control group, where no such significant changes occurred. HRV analysis showed that the experimental group experienced a significant decrease in the LF component (sympathetic activity) and a decrease in the LF/HF ratio, suggesting a shift toward parasympathetic dominance and reduced stress. Subjectively, the experimental group reported lower mental fatigue scores on the NASA-TLX scale after inhalation, recovering to baseline levels, whereas the control group’s fatigue levels remained elevated. The study concludes that inhaling essential oil has a remarkable effect on decreasing mental fatigue and facilitating relaxation, as evidenced by both physiological indices and subjective reports. These findings validate the use of EEG and HRV as objective tools for evaluating the effects of aromatherapy. The results suggest that essential oil inhalation can effectively mitigate the physiological and psychological impacts of mental stress, offering a potential non-invasive intervention for improving worker well-being and reducing error rates in high-stress environments.

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• neuro workload indices

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• Empirical Findings: physiological data