{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,24]],"date-time":"2026-09-24T17:06:59Z","timestamp":1790269619236,"version":"4.1.0"},"reference-count":31,"publisher":"MDPI AG","issue":"9","license":[{"start":{"date-parts":[[2022,4,21]],"date-time":"2022-04-21T00:00:00Z","timestamp":1650499200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"R&amp;D Program for Forest Science Technology","award":["2021332D10-2123A01"],"award-info":[{"award-number":["2021332D10-2123A01"]}]},{"name":"Kongju National University in 2020","award":["-"],"award-info":[{"award-number":["-"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["IJERPH"],"abstract":"<jats:p>Numerous studies have reported a significant increase in stress experienced by students owing to the COVID-19 pandemic. Recently, interest in stress management using nature-derived substances has increased. However, studies examining the effects of olfactory stimulation by fir are lacking. The aim of this study was to investigate the physiological and psychological effects of inhaling fir essential oil. Additionally, differences between male and female participants were compared. Twenty-six university students (16 female and 10 male students; mean age, 21.5 \u00b1 1.9 years) participated in this study. Fir essential oil was used for olfactory stimulation, with normal room air as the control. The odor was administered for 3 min. Heart rate variability and heart rate were used as indicators of autonomic nervous system activity. The Profile of Mood States and State-Trait Anxiety Inventory were used as psychological indicators. The ln(Low Frequency\/High Frequency) ratio, which is an indicator of sympathetic nervous activity reflecting a stressful or aroused state during stimulation with fir essential oil, was significantly lower than during the control condition. Assessment of psychological indicators showed that the positive mood of \u201cvigor\u201d improved significantly and negative moods of \u201ctension\u2013anxiety\u201d, \u201cdepression\u201d, \u201canger\u2013hostility\u201d, \u201cfatigue\u201d and anxiety levels reduced significantly after inhaling fir essential oil compared to the control condition. This study showed that inhalation of fir essential oil has physiologically and psychologically relaxing effects, with differences in results depending on the sex of the participants.<\/jats:p>","DOI":"10.3390\/ijerph19095063","type":"journal-article","created":{"date-parts":[[2022,4,22]],"date-time":"2022-04-22T05:07:22Z","timestamp":1650604042000},"page":"5063","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":26,"title":["Physiological and Psychological Relaxation Effects of Fir Essential Oil on University Students"],"prefix":"10.3390","volume":"19","author":[{"given":"Choyun","family":"Kim","sequence":"first","affiliation":[{"name":"Department of Forest Science, Kongju National University, 54 Daehak-ro, Yesan-eup, Yesan-gun 32439, Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1924-1053","authenticated-orcid":false,"given":"Chorong","family":"Song","sequence":"additional","affiliation":[{"name":"Department of Forest Science, Kongju National University, 54 Daehak-ro, Yesan-eup, Yesan-gun 32439, Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2022,4,21]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"152191","DOI":"10.1016\/j.comppsych.2020.152191","article-title":"Stress and Anxiety Among University Students in France During COVID-19 Mandatory Confinement","volume":"102","author":"Husky","year":"2020","journal-title":"Compr. Psychiatry"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"681","DOI":"10.1080\/00981389.2020.1859044","article-title":"Anxiety Levels Among Social Work Students During the COVID-19 Lockdown in Spain","volume":"59","year":"2020","journal-title":"Soc. Work Health Care."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"797","DOI":"10.2147\/PRBM.S266511","article-title":"Examining Anxiety, Life Satisfaction, General Health, Stress and Coping Styles During COVID-19 Pandemic in Polish Sample of University Students","volume":"13","author":"Rogowska","year":"2020","journal-title":"Psychol. Res. Behav. Manag."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"695","DOI":"10.3389\/fpsyt.2020.00695","article-title":"A Survey of Attitudes, Anxiety Status, and Protective Behaviors of the University Students During the COVID-19 Outbreak in Turkey","volume":"11","author":"Akdeniz","year":"2020","journal-title":"Front. Psychiatry"},{"key":"ref_5","first-page":"644","article-title":"A Qualitative Study on the Stress of Undergraduate Due to COVID-19","volume":"21","author":"Kim","year":"2021","journal-title":"J. Korea Contents Assoc."},{"key":"ref_6","unstructured":"(2020, April 02). Cibyl. Available online: https:\/\/cibyl.com\/."},{"key":"ref_7","first-page":"267","article-title":"Children and Stress: An Exploratory Study of Stressors and Symptoms","volume":"35","author":"Omizo","year":"1988","journal-title":"Sch. Couns."},{"key":"ref_8","first-page":"219","article-title":"The Verification of Intervening Effect of Youth Activity on the Relationship Between Stress and Life Satisfaction of Adolescents","volume":"19","author":"Kim","year":"2012","journal-title":"Korean J. Youth Stud."},{"key":"ref_9","first-page":"407","article-title":"Nature therapy","volume":"Volume 10","author":"Osaki","year":"2011","journal-title":"Designing our Future: Local Perspectives on Bioproduction, Ecosystems and Humanity"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"879","DOI":"10.1080\/00420989650011645","article-title":"Health levels influenced by urban residential conditions in a megacity\u2013Tokyo","volume":"33","author":"Tanaka","year":"1996","journal-title":"Urban Stud."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"18","DOI":"10.1007\/s12199-009-0086-9","article-title":"The Physiological Effects of Shinrin-yoku (Taking in the Forest Atmosphere or Forest Bathing): Evidence from Field Experiments in 24 Forests Across Japan","volume":"15","author":"Park","year":"2010","journal-title":"Environ. Health Prev. Med."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"123","DOI":"10.2114\/jpa2.26.123","article-title":"Physiological Effects of shinrin-yoku (Taking in the Atmosphere of the Forest)\u2014Using Salivary Cortisol and Cerebral Activity as Indicators","volume":"26","author":"Park","year":"2007","journal-title":"J. Physiol. Anthropol."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"2532","DOI":"10.3390\/ijerph120302532","article-title":"Physiological and Psychological Effects of Forest Therapy on Middle-Aged Males with High-Normal Blood Pressure","volume":"12","author":"Ochiai","year":"2015","journal-title":"Int. J. Environ. Res. Public Health"},{"key":"ref_14","first-page":"20","article-title":"Aromatherapy: The Practice of Aroma\u2019s in Una ni Medicine","volume":"6","author":"Naaz","year":"2017","journal-title":"J. AYUSH Ayurveda Yoga Una ni Siddha Homeopath."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"44","DOI":"10.1186\/s40101-015-0082-2","article-title":"Physiological Effect of Olfactory Stimulation by Hinoki Cypress (Chamaecyparis obtusa) Leaf Oil","volume":"34","author":"Ikei","year":"2015","journal-title":"J. Physiol. Anthropol."},{"key":"ref_16","first-page":"90","article-title":"Physiological and Psychological Effects of Olfactory Stimulation with D-Limonene","volume":"28","author":"Joung","year":"2014","journal-title":"Adv. Horti Sci."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"537","DOI":"10.1007\/s10086-015-1495-6","article-title":"Comparison of the Effects of Olfactory Stimulation by Air-Dried and High-Temperature-Dried Wood Chips of Hinoki Cypress (Chamaecyparis obtusa) on Prefrontal Cortex Activity","volume":"61","author":"Ikei","year":"2015","journal-title":"J. Wood Sci."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"333","DOI":"10.11628\/ksppe.2015.18.4.333","article-title":"Assay of Terpene Compounds Contained in the Tree for Forest Healing","volume":"18","author":"Yeon","year":"2015","journal-title":"J. People Plants Environ."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"228","DOI":"10.1016\/j.ejphar.2007.04.059","article-title":"Anti-Inflammatory Effects of Compounds Alpha-Humulene and (\u2212)-Trans-Caryophyllene Isolated from the Essential Oil of Cordia Verbenacea","volume":"569","author":"Fernandes","year":"2007","journal-title":"Eur. J. Pharmacol."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"S27","DOI":"10.1111\/j.1440-1681.2004.04102.x","article-title":"Effects of Phytoncides on Blood Pressure Under Restraint Stress in SHRSP","volume":"31","author":"Kawakami","year":"2004","journal-title":"Clin. Exp. Pharmacol. Physiol."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"406","DOI":"10.1007\/BF02863092","article-title":"Traditional Medicine in Turkey VII. Folk Medicine in Middle and West Black Sea Regions","volume":"49","author":"Fujita","year":"1995","journal-title":"Econ. Bot."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"433","DOI":"10.11628\/ksppe.2018.21.5.433","article-title":"Effects of the Aromatherapy Program Using Fir Needle Essential Oil on Stress, Sleep Quality and Fatigue in Middle-Aged Women","volume":"21","author":"Hong","year":"2018","journal-title":"J. People Plants Environ."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"223","DOI":"10.11628\/ksppe.2018.21.3.223","article-title":"Effects of Fragrance Components of Abies holophylla Max. on Stress Relief and Improvement of Vascular Functio","volume":"21","author":"Baik","year":"2018","journal-title":"J. People Plants Environ."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"79","DOI":"10.1016\/j.autneu.2003.08.002","article-title":"Autonomic Responses During Inhalation of Natural Fragrance of \u201cCedrol\u201d in Humans","volume":"108","author":"Dayawansa","year":"2003","journal-title":"Auton. Neurosci."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"568","DOI":"10.1007\/s10086-016-1576-1","article-title":"Effects of Olfactory Stimulation by \u03b1-Pinene on Autonomic Nervous Activity","volume":"62","author":"Ikei","year":"2016","journal-title":"J. Wood Sci."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"87","DOI":"10.1111\/ijn.12229","article-title":"The Effects of Aromatherapy in Relieving Symptoms Related to Job Stress Among Nurses","volume":"21","author":"Chen","year":"2015","journal-title":"Int. J. Nurs. Pract."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"61","DOI":"10.34272\/forest.2011.15.2.007","article-title":"Effect of Inhalation of Essential Oil (Chamaecyparis obtuse) on Stress and Depression in College Students","volume":"15","author":"Lee","year":"2011","journal-title":"J. Korean Inst. For. Recreat."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"234","DOI":"10.1111\/j.1749-6632.1974.tb49859.x","article-title":"Some Experiments on Sex Differences in Odor Perception","volume":"237","author":"Koelega","year":"1974","journal-title":"Ann. N. Y. Acad. Sci. USA"},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"129","DOI":"10.1093\/chemse\/7.2.129","article-title":"Odor Identification by Males and Females: Predictions vs. Performance","volume":"7","author":"Cain","year":"1982","journal-title":"Chem. Senses"},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"293","DOI":"10.1016\/0013-4694(95)00055-4","article-title":"Olfactory Event-Related Potentials in Normal Human Subjects: Effects of Age and Gender","volume":"95","author":"Evans","year":"1995","journal-title":"Electroencephalogr. Clin. Neurophysiol."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"77","DOI":"10.1093\/chemse\/bjn054","article-title":"Mood Induction with Olfactory Stimuli Reveals Differential Affective Responses in Males and Females","volume":"34","author":"Seubert","year":"2009","journal-title":"Chem. 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