精油暨感官體驗活動對國人紓壓效益之研究

Abstract

People inherently possess an affinity for the natural world and attractive fragrances, much like butterflies that are drawn to flowers or trees that lean toward sunlight. Numerous empirical studies have indicated that natural environments, particularly forests, have more beneficial effects on physical and mental health than urban settings. However, despite the natural environment being closely related to health, citizens are unable to frequently visit the wild mountains and forests to get close to nature due to their busy and fast-paced lives. This was especially the case during the coronavirus disease 2019 (COVID-19) pandemic. Under various protective control measures (e.g., cross-regional travel restrictions and the closure or regulation of public recreational areas), travel and leisure became more challenging. Therefore, this study aimed to explore whether creating an indoor environment containing natural elements (such as essential oils [EOs]) could make participants feel as if they were immersed in a forest atmosphere, thereby stimulating a stress-relieving and relaxing effect. The study objectively monitored participants’ physiological responses using two instruments: a heart rate variability (HRV) sensor to measure changes in sympathetic and parasympathetic nerve activity and an electroencephalogram (EEG) sensor to record changes in brainwaves. Participants also filled out the State-Trait Anxiety Inventory–State (STAI-S) questionnaire to subjectively evaluate their psychological state and emotions. The psychophysiological data for the participants were collected before and after the experiment and analyzed statistically to evaluate the stress-relieving effect. Plant EOs are extracted from natural plants (trees and flowers), and they are also one of the main components of forest phytoncides. Commercially available EOs are typically extracted from various parts of plants, such as the seeds, flowers, leaves, roots, stems, fruit (the peel), bark (resin), or wood, using methods like steam distillation, cold pressing, or solvent extraction. The use of EOs for aromatherapy is a stress-relief method that can be easily integrated into daily life and is rich in natural elements. However, the effectiveness of EOs may vary with concentration, and different combinations of the compounds in EOs may interact with different neurotransmitter pathways, resulting in diverse effects. This study initially selected six candidate EOs (Lavandula angustifolia, Citrus bergamia, Salvia sclarea, Cananga odorata, Citrus aurantium, and Pseudotsuga menziesii) that may have a stress-relieving effect through literature review. Stress relaxing effectiveness assessment to screen out two EOs with better stress-relieving effects. Among the 68 participants aged 21 to 79 years in an experiment, the results showed that Lavandula angustifolia (L. angustifolia) and Pseudotsuga menziesii (P. menziesii) EOs had better stress-relieving effects after participants inhaled these six candidates of EOs. Physiological parameters, including the standard deviation of normal-to-normal intervals, normalized high frequency, and high-alpha waves measurements, showed an upward trend; while other physiological parameters, such as normalized low frequency, low- to high-frequency ratio power, high-beta waves, and gamma waves, showed a downward trend, indicating a relaxing effect. Subsequently, this study then determined the concentration with the better stress-relieving effect from the two selected EOs (L. angustifolia and P. menziesii) with better stress-relieving effects. To do this, tests were carried out using different concentrations (2.5%, 5.0%, and 10.0%). Twenty-two subjects aged 20 to 43 years participated. The results showed that L. angustifolia and P. menziesii EOs had more significant stress-relieving effects at a concentration of 2.5%. Multiple physiological parameters associated with stress-relieving effects exhibited statistically significant changes (P < 0.05). Furthermore, although some studies have reported the positive effects of activities such as horticultural activity or making nature-based art, which can improve quality of life and promote health, limited studies have explored the benefits of combining these experiential activities with EOs diffusion. Therefore, this study also aimed to explore whether diffusing EOs during sensory experience activities contributed to a more relaxed and healthier living environment. Accordingly, based on the results of the previous experiments, diffusion of L. angustifolia and P. menziesii EOs at a concentration of 2.5% (which resulted in the best relaxing effect), was separately combined with sensory experience activities such as leaf printing (257 participants aged 20 to 90 years), Kokedama (15 participants aged 29 to 70 years), or still-life fruit and vegetable painting (30 participants aged 59 to 79 years). During each sensory experience activity, water vapor, water vapor containing P. menziesii EO, water vapor, and water vapor containing L. angustifolia EO were sequentially diffused. The results showed that the influence of EOs was notably observed during the experiment. Compared with the process of experiencing activities accompanied by water vapor diffusion alone, the changes in HRV and EEG physiological parameters, reflecting relaxation effects, were more significant (P < 0.05) when accompanied by EOs diffusion. This indicated that diffusing EOs enhanced the relaxing effects of the activities. These overall relaxing results were also supported by a general decrease in anxiety levels after the subjective assessment on the STAI-S scale. In conclusion, the results from the scientific quantification of psychophysiological states data indicated that inhaling EOs had a relaxing effect, with different types and concentrations of EOs producing varying effects. This study recommended using 2.5% concentrations of L. angustifolia and P. menziesii EOs for optimal results. The materials used in these indoor nature activities are easy to obtain, and there are no geographical restrictions, such as there are for forest bathing. Therefore, they could provide citizens with simple ways to relieve stress in their daily lives, especially when access to outdoor activities such as mountain and forest recreation is restricted, helping to reduce stress, pleasure the body and mind, thereby boosting immunity and improving the overall quality of life and happiness.

人們對「大自然」和「香氣」有與生俱來的喜愛，如蝶之慕花、木之向陽。許多實證研究表明自然環境，尤其是森林場域，相較於城市環境更有助於促進身心健康。然而，儘管自然環境與健康的關係密切，但現代國人由於工作忙碌與快節奏的生活步調，無法頻繁前往野外山林去親近自然，特別是在嚴重特殊傳染性肺炎 (Coronavirus disease 2019, COVID-19) 疫情的大流行期間，在各種防護管控措施之下 (如跨區域交通限制、公共休閒場域封閉或管制)，使得出遊休憩變得更具挑戰性。 因此，本研究擬探討營造一個含有自然元素 (如植物精油[Essential Oils, EOs] )的室內環境，是否能讓參與者感覺彷彿沉浸在森林氛圍中，從而達到紓壓放鬆的效果。研究使用兩種儀器客觀地監測參與者的生理反應，包括心率變異 (Heart Rate Variability, HRV) 傳感器用於測量交感神經和副交感神經活動的變化，以及腦波 (Electroencephalogram, EEG) 傳感器用於記錄腦電波的變化；參與者也填寫了狀態焦慮量表 (State-Trait Anxiety Inventory–State, STAI-S)，以主觀評估其心理狀態和情緒。於試驗前後蒐集參與者的生心理數據，並進行統計分析，以評估紓壓效益。 植物EOs是源於大自然植物 (樹木和花草) 所萃取，是森林芬多精 (phytoncides) 的組成之一。市售商品化EOs是從植物的種子、花朵、葉、根、莖、果 (皮)、樹皮 (樹脂) 或木質部等部位，透過水蒸氣蒸餾法、冷壓法、或溶劑萃取法等方式提取的。薰香EOs是一種能簡易融入日常生活中，且富含自然元素的緩解壓力之方法。然而，EOs的有效性可能會因濃度之不同而異；且EOs中化合物的不同組合，亦可能與不同的神經傳遞物質途徑相互作用，從而產生不同的效果。 本研究首先透過文獻回顧選取六種可能具有紓壓效果的候選EOs (狹葉薰衣草[Lavandula angustifolia] EO、佛手柑[Citrus bergamia] EO、快樂鼠尾草[Salvia sclarea] EO、伊蘭伊蘭[Cananga odorata] EO、苦橙葉[Citrus aurantium] EO、和道格拉斯杉[Pseudotsuga menziesii ] EO)，進行紓壓效益評估，以篩選出兩種紓壓效果較佳的EOs。在68名年齡介於21至79歲參與者的試驗中，結果顯示參與者在嗅吸這六種候選EOs後，以Lavandula angustifolia (L. angustifolia) EO與Pseudotsuga menziesii (P. menziesii) EO的紓壓效果較佳。其生理參數:正常心跳間距之標準差 (standard deviation of normal-to-normal intervals)、標準化高頻功率 (normalized high frequency)、和 high-alpha波之數值呈現上升趨勢；而其它生理參數:標準化低頻功率 (normalized low frequency)、低頻與高頻功率比 (Low- to High-Frequency ratio power)、high-beta波和gamma波則呈現下降趨勢，表明有放鬆效果。 隨後，本研究再從所篩選出來紓壓效果較佳的兩種EOs (L. angustifolia 與P. menziesii EOs) 中，找出紓壓效果較佳的濃度。為此，使用不同濃度 (2.5%、5.0%、10.0%) 進行了測試。有22名年齡為20至43歲的受試者參與了這項試驗，結果表明L. angustifolia EO與P. menziesii EO在濃度為2.5%時，具有更佳的紓壓效益，其多項與紓壓效果相關之生理參數達到統計顯著差異 (P < 0.05)。 此外，儘管有研究報導從事園藝活動、或自然藝術創作等活動，可以改善生活品質和促進健康。然而，少有研究在探討進行體驗活動的時候，同時討論結合擴香EOs的益處。因此，本研究亦擬探討在感官體驗活動中擴散EOs，是否有助於營造更放鬆、更健康的生活環境。故根據前述的試驗結果，將紓壓效果較佳之濃度2.5%的L. angustifolia EO與P. menziesii EO，以擴香方式分別與葉拓 (257名年齡為20至90歲的參與者)、苔球 (15名年齡為29至70歲的參與者) 和蔬果靜物畫 (30名年齡為59至79歲的參與者) 的感官體驗活動相結合。在每次的感官體驗活動進行期間，均同時依序擴散水蒸氣、P. menziesii EO、水蒸氣、L. angustifolia EO，結果顯示於試驗期間可明顯觀察到EOs的影響。與僅伴隨著水蒸氣擴散的體驗活動之期間相比，當伴隨著EOs擴散時，HRV和EEG等生理指標的放鬆效果變化更為顯著 (P < 0.05)，表明EOs的擴散增強了活動之放鬆效益。這整體紓壓的結果，亦由STAI-S量表進行主觀評估之後測的焦慮程度普遍下降所應證。 綜上所述，透過科學量化所獲得的生心理狀態數據結果表明，吸入EOs具有放鬆效果，而不同EOs種類和濃度會產生不同的影響，本研究建議使用濃度2.5% 之L. angustifolia EO和P. menziesii EO以達最佳效果。這些室內自然活動所使用的材料取得容易，不存在如森林休憩等的區域限制。因此，可以為國人在日常生活中，提供簡易的紓壓方法之參考，特別是在山林休閒等戶外活動受到限制的時候，有助於減輕壓力、愉悅身心，從而增強免疫力，提升整體生活品質與幸福感。