Effects of Inhaling Essential Oil on Decreasing Mental Fatigue:
Authors: A Physiological Indices Study
Abstract: Essential oil inhalation is one of the important aromatherapy. Essential oils are always used to dispel fatigue by officer workers. Owing to lack of objective measured data of the effect on decreasing fatigue for essential oil, the reliability of subjective experiment from questionnaire has always been challenged. The purpose of this study is to evaluate the effect on decreasing mental fatigue for inhaling essential oil by using physiological indices including Electroencephalogram (EEG) and heart rate variability (HRV). The basic and ratio indices of EEG power reflecting the drowsiness and relaxation levels, and the variety of HRV reflecting the condition of mental workload were used to evaluate the effect on decreasing mental fatigue substantially for inhaling essential oil. Twenty college students aged from twenty to twenty-five years old recruited for subjects participated the experimental test. Before experimental test, the subjects must fill in NASA-TLX self-evaluation inventory and measured their EEGs and heart rate variability (HRV) for five minutes. The subjects undertook their school courses about four hours and then inhaled essential oil. The study found that EEG power ratio indices (+)/ decreased and / increased after inhaling essential oil. It demonstrated that the subjects inhaled essential oil would facilitate their relaxation obviously. The result of heart rate variability showed that low-frequency component LF decreased, high-frequency component HF increased and LH/HF decreased obviously after inhaling essential oil. For NASA-TLX rating scales measurement, the participants subjectively felt more relaxed. It revealed that the subjects had remarkable effect to decreasing mental fatigue after inhaling essential oil. To summarize as mentioned above, our study found that essential oil had obvious effect on decreasing mental fatigue and facilitating relaxation.
Keywords: Essential Oils, EEG, Heart Rate Variability, mental fatigue, relaxation level
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