Electroencephalographic Study of Essential Oils for Stress Relief

Transcription

1 Applied Mechanics and Materials Online: ISSN: , Vol. 437, pp doi: / Trans Tech Publications, Switzerland Electroencephalographic Study of Essential Oils for Stress Relief Chien-Wei Liu 1,a, Ching-Sung Wang 2,b, Kai-Jen Chuang 3,c, Chia-Chi Lo 4,d and Chien-Tsu Chen 3,e 1 Department of Information Management, St. Mary's Junior College of Medicine, Nursing and Management, Yilan, Taiwan 2 Department of Electronic Engineering, Oriental Institute Technology, Taipei, Taiwan 3 School of Medicine, Taipei Medical University, Taipei, Taiwan 4 Department of Orthopaedic Surgery, Changhua Christian Hospital, Changhua, Taiwan a cwliu@smc.edu.tw, b ff020@mail.oit.edu.tw, c kjc@tmu.edu.tw, d s070@eip.mkc.edu.tw, e chenctsu@tmu.edu.tw Corresponding Author: Prof. Chien-Tsu Chen, School of Medicine, Taipei Medical University, No.250, Wuxing St., Taipei 110, Taiwan Keywords: electroencephalogram, essential oils, stress relief Abstract. Nowadays, electroencephalogram (EEG) is widely used in medical applications. Besides the examination for brain diseases, EEG is used to observe how the surroundings affect people s emotion. There are many essential oils, and most claim that they are effective in soothing soul and calming. Currently, there is no related EEG scientific experiment to verify this claim, This study attempted to understand whether common essential oils for stress relief have actual emotional relaxation effects on the human brain by EEG observation; the level of efficacy was also observed. From the results of this study, rose essential oil had the best effect of stress relief and relaxation in both genders (P<0.05). It suggested that peppermint essential oil had the best effect of relaxation in male (P<0.05) and rose essential oil had the best effect of relaxation in females (P<0.05) when it was analyzed by gender. Introduction Brain waves are generated by the neurons in the brain. Scientists fixed the electrodes of the electroencephalogram (EEG) on the scalp to record the signal expression of continuous cerebral activity. The waveform of the EEG would suggest the mental state of a human. As the recorded shape is undulating, it is also known as brain waves, electroencephalogram, and is commonly known as EEG. EEG is widely used in clinical diagnosis [1]. It can be used to screen epilepsy, depression, dementia, stroke, encephalitis, coma and other brain diseases. It can also be used to test the psychological state, for example, angry, pleasant, tensed, relaxed and etc. With the changing society and lifestyle, people bear a number of physical and psychological stresses. The poor health condition caused by stress has been addressed. When the source of stress outweighs the amount that the body and mind could bear, it is the major cause of physical and psychological conditions. Long-term accumulation of stress could be irreversible. Therefore, people have to find their own method to relieve stress and relax to prevent disease resulting from excessive stress. Many local and foreign studies on aromatherapy focused on the discussion of human skin absorbing essential oils. This study discusses the level of relaxation efficacy of inhaled essential oils via the human olfactory organs. Thus, this study intended to observe the effects of rose, lavender, sandalwood and peppermint essential oils for stress relief by EEG. It analyzed the relaxation efficacy of different essential oils and the actual relaxation efficacy and its level of the abovementioned essential oils. If the essential oils are effective in soothing the soul and calming the body, like listening to music, it will be another good option in the future for stress relief. All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of Trans Tech Publications, (ID: , Pennsylvania State University, University Park, USA-12/05/16,21:31:35)

2 1086 Industrial Design and Mechanics Power II Materials and Methods The cerebral cortex can be divided by four regions: frontal lobe, parietal lobe, occipital lobe and temporal lobe. The frontal lobe dominates judgment, thinking, personality, motivation and suppression. The parietal lobe is a comprehensive analysis center which receives and processes sensory information, such as pain, warmth, pressure, shape, size and texture of an object. The occipital lobe is the visual center which receives images. The temporal lobe dominates auditory, taste and smell centers; it can formulate voices into a sentence. The two sides of the temporal lobe are important regions for memory function. The EEG is generated by neurons. It is a complex of a majority of neuron s potential within a specific time for transmitting and receiving messages by electrical signals. It can access the potential difference of the cerebral cortex. This study used the EGI Geodesic EEG System (GES) 300 and adhesive electrodes for the test. Besides, the collection of brain wave signals, the locations of electrodes, the collection methods, the interference exclusion are important in EEG and are factors that affect the operation and performance of the system. If the locations of electrodes and the adhesions of electrodes are different from test to test for the same subject, the EEG obtained would be different. Thus, records could not be compared. This study used the International System of Electrode Placement and allowed the electrode locations on the subject s scalp to be consistent (as shown in Figure 1) [2]. F represents the frontal lobe; T represents the temporal lobe; C represents the central lobe; P represents the parietal lobe and O represents the occipital lobe. Fig. 1. International System of Electrode Placement location map EEG mainly reflects the cerebral potential. Currently, according to different frequency ranges and amplitudes, EEG has four waveforms; Alpha wave (α), Beta wave (β), Theta wave (θ) and Delta wave (δ) [3]. The frequency ranges and the definition of the four waveforms are described as follows: (1) Alpha (α): A waveform that ranges from 8~13Hz; generally when the subject is conscious, quiet and at rest, there are more periodic waves with larger amplitude. (2) Beta (β): A waveform that ranges from 13~50Hz; generally the subject is conscious and alert and is ready to react to the external stimulus, or the subject is stressful and agitated or excited. (3) Theta (θ): A waveform ranges from 4~8Hz; it generally appears in the parietal region and temporal region of children. It is more significant when the subject is unconscious, going into sleep or deeply relaxed. (4) Delta (δ): A waveform lower than 3; normally, a conscious adult would not have δ wave. It appears when a subject is sleeping deeply and has difficultly to wake, or has anesthesia or hypoxia. This study used lavender, rose, sandalwood and peppermint essential oils for stress relief [4,5]. For the study design, the above four essential oils are the experimental group. Air is used in a blank test as the control group. There are two test environments and spaces; one is a 9 m 2 laboratory; another is the observation and control room. One-way glass is installed between the two rooms to prevent

3 Applied Mechanics and Materials Vol interferences during tests. All of the soundproofed and anti-electromagnetic wave facilities of the test environment are in a medical grade auditory room. A silent air-conditioning system keeps the room thermostat at 25. There were 20 subjects in this study; 10 male and 10 female. The mean age was 20 years old. The perfuming method was instilling essential oils into the aromatherapy lamp. The essential oil was volatilized in the air by indirect heating to achieve the perfuming effects. The subject was tested with one essential oil each day. Each subject was tested for 10 minutes in the laboratory. The subjects closed their eyes while lying on a bed. Synchronized wave pattern identification and graphic analysis were conducted by Net Station Review 4.3 (Net Station, Electrical Geodesics Inc.). Finally, analysis of variance (ANOVA) was used to analyze the EEG values were analyzed. The EEG observation locations of the frontal lobe were Fp1, Fp2, F3, F4, Fz, F7 and F8. Results and Discussion The mean brain wave amplitude obtained from the frontal lobe at Fp1, Fp2, F3, F4, Fz, F7 and F8 by the EEG system in this study are shown in Table 1. From the values presented in Table 1, β wave was greater than α wave in both genders when inhaling air. It implied that, people were alert in a normal environment without interference. Males were more alert than females. The test results of each essential oil suggested that, compared to air (blank test), α wave and β wave were greater when subjects inhaled essential oils in both genders. α wave and β wave would not increase alone. According to Figure 3, α wave and β wave variations suggested that, the level of relaxation of each essential oil was different in males and females. Peppermint (3.95%) and sandalwood (1.91%) had positive relaxation reactions in males; rose (-2.97%) and lavender (-2.82%) would bring stress and excitement. Rose (4.09%) and sandalwood (3.64%) had positive relaxation reactions in females; peppermint (-5.07%) and lavender (-1.37%) would bring stress and excitement. Table 1. Brain wave amplitude and variation obtained by EEG system Mean brain wave amplitude (µv) Male Female α Variation β Variation (α-β)/β α Variation β Variation (α-β)/β Air (Blank) % % Lavender % % % % % % Rose % % % % % 4.09 % Sandalwood % % 1.91 % % % 3.64 % Peppermint % % 3.95 % % % % In order to further understand the effect of each essential oil on EEG, this study used repeated measure ANOVA. The statistical results are as follows: The mean α wave and β wave had significant differences between the essential oils (the experimental group) and the blank test (the control group) in both genders (P<0.05). The order of α wave (from strong to weak) was rose, peppermint, lavender and sandalwood. The order of β wave (from strong to weak) was lavender, rose, peppermint and sandalwood. The comparison of α wave and β wave intensity of each essential oil is described as follows: rose (α>β), peppermint (β>α), lavender (β>α), sandalwood (α>β). From the above results, rose and sandalwood essential oils had stress relief effects in both genders; rose essential oil had the best effects of stress relief. However, lavender and peppermint did not have a stress relief effect and would create stress. β wave of lavender was greater than β wave of peppermint; thus lavender would brought the most stress and excitement among the four essential oils. ANOVA was conducted to each essential oil and blank test in both genders, and the mean α wave and β wave had significant differences (P<0.05). In order to obtain further results, the essential oils were analyzed by gender. The results are as follows:

4 1088 Industrial Design and Mechanics Power II 1. Lavender: α waves had significant difference between the experimental group and the control group for females (P<0.05); β waves had no significant difference (P>0.05). β wave was greater than α wave. Thus, lavender did not have stress relief effects on females. α waves and β waves had significant differences between the experimental group and the control group for males (P<0.05). β wave was greater than α wave. Thus, lavender did not have stress relief effects on males. 2. Rose: α waves had significant difference between the experimental group and the control group for females (P<0.05); β waves had no significant difference (P>0.05). α wave was greater than β wave. Thus, rose had stress relief effects on females. α waves and β waves had significant differences between the experimental group and the control group for males (P<0.05). β wave was greater than α wave. Thus, rose did not have stress relief effects on males. 3. Sandalwood: α waves and β waves had no significant difference between the experimental group and the control group for females and males in individual analysis (P>0.05). Thus, sandalwood had insignificant stress relief effects on males and females. 4. Peppermint: α waves and β waves had no significant difference between the experimental group and the control group for females (P>0.05). Thus, peppermint did not have significant stress relief effects on females. α waves and β waves had significant differences between the experimental group and the control group for males (P<0.05) α wave was greater than β wave. Thus, peppermint had stress relief effects on males. Conclusions This study included 20 subjects, 10 male and 10 female. The mean age was years old. They inhaled lavender, rose, sandalwood and peppermint essential oils which claimed stress relief effects. The perfuming method was used to observe the EEG changes. Rose and sandalwood essential oils had effects of stress relief and relaxation in both genders. Rose essential oil had the best effect of stress relief. The results were different using ANOVA which analyzed by genders. Rose essential oil had the best effect of stress relief in females. Peppermint essential oil had the best effect of stress relief in males. It should be noted that lavender essential oil did not have stress relief effects in the overall study results in both genders or by gender; it would actually bring excitement or stress. From the above results, it is suggested that the age of subjects should be expanded if the effects of each essential oil on emotions are to be further explored. It will further understanding whether the same essential oil has different EEG reactions on different age groups and genders. This may provide a clear position for each essential oil on the emotional effect. References [1] K. Lemon, An assessment of treating depression and anxiety with aromatherapy, International journal of aromatherapy 14 (2004) [2] J. Malmivuo, R. Plonsey, Bioelectromagnetism-Principles and Applications of Bioelectric and Biomagnetic Fields, Oxford University Press, New York, [3] W.J. Ray, The electrocortical system. In J. Cacioppo & L. Tassinary (Eds.), Principles of Psychophysiology. Cambridge, Cambridge University Press, New York, [4] B. Gerhard, J. Leopold, J. Walter, P. Christine, D. Hermann, Fragrance compounds and essential oil with sedative effects upon inhalation, Journal of Pharmaceutical Science 82 (2001) [5] H.M. Cavanagh, J.M. Wilkinson, Biological activities of lavender essential oil. Phytotherapy research : PTR, Phytotherapy research 16 (2002)

5 Industrial Design and Mechanics Power II / Electroencephalographic Study of Essential Oils for Stress Relief / DOI References [5] H.M. Cavanagh, J.M. Wilkinson, Biological activities of lavender essential oil. Phytotherapy research : PTR, Phytotherapy research 16 (2002) /ptr.1103