2. Materials and Methods
2.1. Identifying the Research Question
2.2. Identifying Relevant Studies
2.3. Study Selection
3.1. Charting the Data
3.2. Collating, Summarizing, and Reporting the Results
3.2.1. Cortisol Metrics
3.2.2. Horticulture Therapy
3.2.3. Forest Bathing
3.2.4. Greenspace Exposure (GE)
3.2.5. Outdoor Activity Programs
4.1. Heterogeneity of Study Design and Sampling Size
4.2. Limitations of Cortisol Data Collection Methods and Analysis
4.3. Limitations of This Review
Conflicts of Interest
- Twohig-Bennett, C.; Jones, A. The health benefits of the great outdoors: A systematic review and meta-analysis of greenspace exposure and health outcomes. Environ. Res. 2018, 166, 628–637. [Google Scholar] [CrossRef] [PubMed]
- Kellert, S.R.; Case, D.J.; Escher, D.; Witter, D.J.; Mikels-Carrasco, J.; Seng, P.T. The Nature of Americans: Disconnection and Recommendations for Reconnection; The Nature of Americans National Report, DJ Case and Associates: Mishawaka, IN, USA, 2017; Volume 11, p. 2018. [Google Scholar]
- Barnes, M.R.; Donahue, M.L.; Keeler, B.L.; Shorb, C.M.; Mohtadi, T.Z.; Shelby, L.J. Characterizing nature and participant experience in studies of nature exposure for positive mental health: An integrative review. Front. Psychol. 2019, 9, 2617. [Google Scholar] [CrossRef]
- Bowler, D.E.; Buyung-Ali, L.M.; Knight, T.M.; Pullin, A.S. A systematic review of evidence for the added benefits to health of exposure to natural environments. BMC Public Health 2010, 10, 456. [Google Scholar] [CrossRef] [PubMed]
- Corazon, S.S.; Sidenius, U.; Poulsen, D.V.; Gramkow, M.C.; Stigsdotter, U.K. Psycho-physiological stress recovery in outdoor nature-based interventions: A systematic review of the past eight years of research. Int. J. Environ. Res. Public Health 2019, 16, 1711. [Google Scholar] [CrossRef] [PubMed]
- Di Nardo, F.; Saulle, R.; La Torre, G. Green areas and health outcomes: A systematic review of the scientific literature. Ital. J. Public Health 2010, 7, 402–413. [Google Scholar]
- Wendelboe-Nelson, C.; Kelly, S.; Kennedy, M.; Cherrie, J.W. A Scoping Review Mapping Research on Green Space and Associated Mental Health Benefits. Int. J. Environ. Res. Public Health 2019, 16, 2081. [Google Scholar] [CrossRef]
- Djernis, D.; Lerstrup, I.; Poulsen, D.; Stigsdotter, U.; Dahlgaard, J.; O’toole, M. A systematic review and meta-analysis of nature-based mindfulness: Effects of moving mindfulness training into an outdoor natural setting. Int. J. Environ. Res. Public Health 2019, 16, 3202. [Google Scholar] [CrossRef]
- Granerud, A.; Eriksson, B.G. Mental Health Problems, Recovery, and the Impact of Green Care Services: A Qualitative, Participant-Focused Approach. Occup. Ther. Ment. Health 2014, 30, 317–336. [Google Scholar] [CrossRef]
- Masterton, W.; Carver, H.; Parkes, T.; Park, K. Greenspace interventions for mental health in clinical and non-clinical populations: What works, for whom, and in what circumstances? Health Place 2020, 64, 102338. [Google Scholar] [CrossRef]
- McMahan, E.A.; Estes, D. The effect of contact with natural environments on positive and negative affect: A meta-analysis. J. Posit. Psychol. 2015, 10, 507–519. [Google Scholar] [CrossRef]
- Haluza, D.; Schönbauer, R.; Cervinka, R. Green perspectives for public health: A narrative review on the physiological effects of experiencing outdoor nature. Int. J. Environ. Res. Public Health 2014, 11, 5445–5461. [Google Scholar] [CrossRef] [PubMed]
- McCormick, R. Does Access to Green Space Impact the Mental Well-being of Children: A Systematic Review. J. Pediatric Nurs. 2017, 37, 3–7. [Google Scholar] [CrossRef]
- Wen, Y.; Yan, Q.; Pan, Y.; Gu, X.; Liu, Y. Medical empirical research on forest bathing (Shinrin-yoku): A systematic review. Environ. Health Prev. Med. 2019, 24, 70. [Google Scholar] [CrossRef] [PubMed]
- Antonelli, M.; Barbieri, G.; Donelli, D. Effects of forest bathing (shinrin-yoku) on levels of cortisol as a stress biomarker: A systematic review and meta-analysis. Int. J. Biometeorol 2019, 63, 1117–1134. [Google Scholar] [CrossRef]
- Markevych, I.; Schoierer, J.; Hartig, T.; Chudnovsky, A.; Hystad, P.; Dzhambov, A.M.; de Vries, S.; Triguero-Mas, M.; Brauer, M.; Nieuwenhuijsen, M.J.; et al. Exploring pathways linking greenspace to health: Theoretical and methodological guidance. Environ. Res. 2017, 158, 301–317. [Google Scholar] [CrossRef]
- Labib, S.M.; Lindley, S.; Huck, J.J. Spatial dimensions of the influence of urban green-blue spaces on human health: A systematic review. Environ. Res. 2020, 180, 108869. [Google Scholar] [CrossRef] [PubMed]
- Moeller, C.; King, N.; Burr, V.; Gibbs, G.R.; Gomersall, T. Nature-based interventions in institutional and organisational settings: A scoping review. Int. J. Environ. Health Res. 2018, 28, 293–305. [Google Scholar] [CrossRef] [PubMed]
- Hunter, R.; Cleland, C.; Cleary, A.; Droomers, M.; Wheeler, B.; Sinnett, D.; Nieuwenhuijsen, M.; Braubach, M. Environmental, health, wellbeing, social and equity effects of urban green space interventions: A meta-narrative evidence synthesis. Environ. Int. 2019, 130, 104923. [Google Scholar] [CrossRef]
- Houlden, V.; Weich, S.; de Albuquerque, J.P.; Jarvis, S.; Rees, K. The relationship between greenspace and the mental wellbeing of adults: A systematic review. PLoS ONE 2018, 13, e0203000. [Google Scholar] [CrossRef]
- Bloomfield, D. What makes nature-based interventions for mental health successful? Bjpsych Int. 2017, 14, 82–85. [Google Scholar] [CrossRef] [PubMed]
- Shanahan, D.F.; Astell-Burt, T.; Barber, E.A.; Brymer, E.; Cox, D.T.C.; Dean, J.; Depledge, M.; Fuller, R.A.; Hartig, T.; Irvine, K.N.; et al. Nature-Based Interventions for Improving Health and Wellbeing: The Purpose, the People and the Outcomes. Sports 2019, 7, 141. [Google Scholar] [CrossRef] [PubMed]
- Hartig, T.; Mitchell, R.; De Vries, S.; Frumkin, H. Nature and Health. Annu. Rev. Public Heal. 2014, 35, 207–228. [Google Scholar] [CrossRef] [PubMed]
- Vujcic, M.; Tomicevic-Dubljevic, J.; Grbic, M.; Lecic-Tosevski, D.; Vukovic, O.; Toskovic, O. Nature based solution for improving mental health and well-being in urban areas. Environ. Res. 2017, 158, 385–392. [Google Scholar] [CrossRef] [PubMed]
- Frumkin, H.; Bratman, G.N.; Breslow, S.J.; Cochran, B.; Kahn, P.H., Jr.; Lawler, J.J.; Levin, P.S.; Tandon, P.S.; Varanasi, U.; Wolf, K.L.; et al. Nature contact and human health: A research agenda. Environ. Health Perspect. 2017, 125. [Google Scholar] [CrossRef]
- Taylor, L.; Hochuli, D.F. Defining greenspace: Multiple uses across multiple disciplines. Landsc. Urban. Plan. 2017, 158, 25–38. [Google Scholar] [CrossRef]
- Robinson, J.M. Nature-Based Interventions for Physical and Mental Health Conditions. 2018. Available online: https://www.researchgate.net/publication/331175674_Nature-based_interventions_for_physical_and_mental_health_conditions (accessed on 1 November 2020).
- WHO. Urban Green Space and Health: Intervention Impacts and Effectiveness; World Health Organization Regional Office for Europe: Copenhagen, Denmark, 2016. [Google Scholar]
- Zartarian, V.; Bahadori, T.; McKone, T. Adoption of an official ISEA glossary. J. Expo. Sci. Environ. Epidemiol. 2004, 15, 1–5. [Google Scholar] [CrossRef]
- Adam, E.K.; Quinn, M.E.; Tavernier, R.; McQuillan, M.T.; Dahlke, K.A.; Gilbert, K.E. Diurnal cortisol slopes and mental and physical health outcomes: A systematic review and meta-analysis. Psychoneuroendocrinology 2017, 83, 25–41. [Google Scholar] [CrossRef] [PubMed]
- Smyth, N.; Rossi, E.; Wood, C. Effectiveness of stress-relieving strategies in regulating patterns of cortisol secretion and promoting brain health. Int. Rev. Neurobiol. 2020, 150, 219–246. [Google Scholar] [CrossRef]
- Roe, J.J.; Thompson, C.W.; Aspinall, P.A.; Brewer, M.J.; Duff, E.I.; Miller, D.; Mitchell, R.; Clow, A. Green Space and Stress: Evidence from Cortisol Measures in Deprived Urban Communities. Int. J. Environ. Res. Public Heal. 2013, 10, 4086–4103. [Google Scholar] [CrossRef]
- Arksey, H.; O’Malley, L. Scoping Studies: Towards a Methodological Framework. Int. J. Soc. Res. Methodol. 2005, 8, 19–32. [Google Scholar] [CrossRef]
- Shadish, W.R.; Cook, T.D.; Campbell, D.T. Experimental and Quasi-Experimental Designs for Generalized Causal Inference; Houghton, Mifflin and Company: Boston, MA, USA, 2002; pp. xxi, 623-xxi, 623. [Google Scholar]
- Kamioka, H.; Tsutani, K.; Mutoh, Y.; Honda, T.; Shiozawa, N.; Okada, S.; Park, S.J.; Kitayuguchi, J.; Kamada, M.; Okuizumi, H.; et al. A systematic review of randomized controlled trials on curative and health enhancement effects of forest therapy. Psychol. Res. Behav. Manag. 2012, 5, 85–95. [Google Scholar] [CrossRef] [PubMed]
- Detweiler, M.B.; Self, J.A.; Lane, S.; Spencer, L.; Lutgens, B.; Kim, D.Y.; Halling, M.H.; Rudder, T.F.; Lehmann, L. Horticultural therapy: A pilot study on modulating cortisol levels and indices of substance craving, posttraumatic stress disorder, depression, and quality of life in veterans. Altern. Ther. Health Med. 2015, 21, 36–41. [Google Scholar] [PubMed]
- Han, A.R.; Park, S.A.; Ahn, B.E. Reduced stress and improved physical functional ability in elderly with mental health problems following a horticultural therapy program. Complement. Ther. Med. 2018, 38, 19–23. [Google Scholar] [CrossRef] [PubMed]
- Ng, K.S.T.; Sia, A.; Ng, M.K.W.; Tan, C.T.Y.; Chan, H.Y.; Tan, C.H.; Rawtaer, I.; Feng, L.; Mahendran, R.; Larbi, A.; et al. Effects of Horticultural Therapy on Asian Older Adults: A Randomized Controlled Trial. Int. J. Environ. Res. Public Health 2018, 15, 1705. [Google Scholar] [CrossRef]
- Van Den Berg, A.E.; Custers, M.H.G. Gardening promotes neuroendocrine and affective restoration from stress. J. Health Psychol. 2011, 16, 3–11. [Google Scholar] [CrossRef] [PubMed]
- Kobayashi, H.; Song, C.; Ikei, H.; Park, B.-J.; Kagawa, T.; Miyazaki, Y. Combined effect of walking and forest environment on salivary cortisol concentration. Front. Public Health 2019, 7, 376. [Google Scholar] [CrossRef]
- Lee, J.; Park, B.J.; Tsunetsugu, Y.; Ohira, T.; Kagawa, T.; Miyazaki, Y. Effect of forest bathing on physiological and psychological responses in young Japanese male subjects. Public Health 2011, 125, 93–100. [Google Scholar] [CrossRef] [PubMed]
- Mao, G.X.; Lan, X.G.; Cao, Y.B.; Chen, Z.M.; He, Z.H.; Lv, Y.D.; Wang, Y.Z.; Hu, X.L.; Wang, G.F.; Yan, J. Effects of short-term forest bathing on human health in a broad-leaved evergreen forest in Zhejiang Province, China. Biomed. Environ. Sci 2012, 25, 317–324. [Google Scholar] [CrossRef]
- Sung, J.; Woo, J.M.; Kim, W.; Lim, S.K.; Chung, E.J. The effect of cognitive behavior therapy-based “forest therapy” program on blood pressure, salivary cortisol level, and quality of life in elderly hypertensive patients. Clin. Exp. Hypertens. 2012, 34, 1–7. [Google Scholar] [CrossRef]
- Beil, K.; Hanes, D. The influence of urban natural and built environments on physiological and psychological measures of stress- A pilot study. Int. J. Environ. Res. Public Health 2013, 10, 1250–1267. [Google Scholar] [CrossRef] [PubMed]
- Grazuleviciene, R.; Vencloviene, J.; Kubilius, R.; Grizas, V.; Danileviciute, A.; Dedele, A.; Andrusaityte, S.; Vitkauskiene, A.; Steponaviciute, R.; Nieuwenhuijsen, M.J. Tracking restoration of park and urban street settings in coronary artery disease patients. Int. J. Environ. Res. Public Health 2016, 13, 550. [Google Scholar] [CrossRef]
- Mokhtar, D.; Abdul Aziz, N.A.; Mariapan, M. Physiological and psychological health benefits of urban green space in Kuala Lumpur: A comparison between Taman Botani Perdana and Jalan Bukit Bintang. Pertanika J. Soc. Sci. Humanit. 2018, 26, 2101–2114. [Google Scholar]
- Olafsdottir, G.; Cloke, P.; Schulz, A.; van Dyck, Z.; Eysteinsson, T.; Thorleifsdottir, B.; Vögele, C. Health benefits of walking in nature: A randomized controlled study under conditions of real-life stress. Environ. Behav. 2020, 52, 248–274. [Google Scholar] [CrossRef]
- Razani, N.; Morshed, S.; Kohn, M.A.; Wells, N.M.; Thompson, D.; Alqassari, M.; Agodi, A.; Rutherford, G.W. Effect of park prescriptions with and without group visits to parks on stress reduction in low-income parents: SHINE randomized trial. PLoS ONE 2018, 13, e0192921. [Google Scholar] [CrossRef]
- Tyrväinen, L.; Ojala, A.; Korpela, K.; Lanki, T.; Tsunetsugu, Y.; Kagawa, T. The influence of urban green environments on stress relief measures: A field experiment. J. Environ. Psychol. 2014, 38, 1–9. [Google Scholar] [CrossRef]
- Calogiuri, G.; Evensen, K.; Weydahl, A.; Andersson, K.; Patil, G.; Ihlebæk, C.; Raanaas, R.K. Green exercise as a workplace intervention to reduce job stress. Results from a pilot study. Work 2015, 53, 99–111. [Google Scholar] [CrossRef] [PubMed]
- Chang, Y.; Davidson, C.; Conklin, S.; Ewert, A. The impact of short-term adventure-based outdoor programs on college students’ stress reduction. J. Adventure Educ. Outdoor Learn. 2019, 19, 67–83. [Google Scholar] [CrossRef]
- Dettweiler, U.; Becker, C.; Auestad, B.H.; Simon, P.; Kirsch, P. Stress in school. Some empirical hints on the circadian cortisol rhythm of children in outdoor and indoor classes. Int. J. Environ. Res. Public Health 2017, 14, 475. [Google Scholar] [CrossRef] [PubMed]
- Niedermeier, M.; Grafetstätter, C.; Hartl, A.; Kopp, M. A Randomized Crossover Trial on Acute Stress-Related Physiological Responses to Mountain Hiking. Int. J. Environ. Res. Public Health 2017, 14, 905. [Google Scholar] [CrossRef]
- Hellhammer, D.H.; Wüst, S.; Kudielka, B.M. Salivary cortisol as a biomarker in stress research. Psychoneuroendocrinology 2009, 34, 163–171. [Google Scholar] [CrossRef] [PubMed]
- Tsigos, C.; Kyrou, I.; Kassi, E.; Chrousos, G.P. Stress, endocrine physiology and pathophysiology. In Endotext; Feingold, K.R., Anawalt, B., Boyce, A., Chrousos, G., Dungan, K., Grossman, A., Hershman, J.M., Kaltsas, G., Koch, C., Kopp, P., et al., Eds.; MDText.com, Inc: South Dartmouth, MA, USA, 2020. [Google Scholar]
- Coad, S.; McLellan, C.; Whitehouse, T.; Gray, B. Validity and reliability of a novel salivary immunoassay for individual profiling in applied sports science. Res. Sports Med. 2015, 23, 140–150. [Google Scholar] [CrossRef]
- El-Farhan, N.; Rees, D.A.; Evans, C. Measuring cortisol in serum, urine and saliva—Are our assays good enough? Ann. Clin. Biochem. 2017, 54, 308–322. [Google Scholar] [CrossRef]
- Segerstrom, S.C.; Sephton, S.E.; Westgate, P.M. Intraindividual variability in cortisol: Approaches, illustrations, and recommendations. Psychoneuroendocrinology 2017, 78, 114–124. [Google Scholar] [CrossRef]
- Stalder, T.; Kirschbaum, C.; Kudielka, B.M.; Adam, E.K.; Pruessner, J.C.; Wüst, S.; Dockray, S.; Smyth, N.; Evans, P.; Hellhammer, D.H.; et al. Assessment of the cortisol awakening response: Expert consensus guidelines. Psychoneuroendocrinology 2016, 63, 414–432. [Google Scholar] [CrossRef]
- Segerstrom, S.C.; Miller, G.E. Psychological stress and the human immune system: A meta-analytic study of 30 years of inquiry. Psychol Bull. 2004, 130, 601–630. [Google Scholar] [CrossRef]
- Vincent, L.W.; van Elisabeth, F.C.R. Clinical applications of cortisol measurements in hair. Eur. J. Endocrinol. 2015, 173, M1–M10. [Google Scholar] [CrossRef]
- Poll, E.-M.; Kreitschmann-Andermahr, I.; Langejuergen, Y.; Stanzel, S.; Gilsbach, J.M.; Gressner, A.; Yagmur, E. Saliva collection method affects predictability of serum cortisol. Clin. Chim. Acta 2007, 382, 15–19. [Google Scholar] [CrossRef]
- van den Berg, M.; Wendel-Vos, W.; van Poppel, M.; Kemper, H.; van Mechelen, W.; Maas, J. Health benefits of green spaces in the living environment: A systematic review of epidemiological studies. Urban. For. Urban. Green. 2015, 14, 806–816. [Google Scholar] [CrossRef]
- Wilson, E.O. Biophilia: The Human Bond with Other Species; Harvard University Press: Cambridge, UK, 1984. [Google Scholar]
- Kaplan, R.; Kaplan, S. The Experience of Nature: A Psychological Perspective; Cambridge University Press: New York, NY, USA, 1989. [Google Scholar]
- Ulrich, R.S. Aesthetic and affective response to natural environment. In Behavior and the Natural Environment; Altman, I., Wohlwill, J.F., Eds.; Springer: Boston, MA, USA, 1983; pp. 85–125. [Google Scholar]
- Plutchik, R. A psychoevolutionary theory of emotions. Soc. Sci. Inf. 1982, 21, 529–553. [Google Scholar] [CrossRef]
- Kaplan, S. The restorative benefits of nature: Toward an integrative framework. J. Environ. Psychol. 1995, 15, 169–182. [Google Scholar] [CrossRef]
- Calogiuri, G.; Litleskare, S.; Fagerheim, K.A.; Rydgren, T.L.; Brambilla, E.; Thurston, M. Experiencing nature through immersive virtual environments: Environmental perceptions, physical engagement, and affective responses during a simulated nature walk. Front. Psychol. 2018, 8, 2321. [Google Scholar] [CrossRef]
- McAllister, E.; Bhullar, N.; Schutte, N.S. Into the woods or a stroll in the park: How virtual contact with nature impacts positive and negative affect. Int. J. Environ. Res. Public Health 2017, 14, 786. [Google Scholar] [CrossRef] [PubMed]
- Mygind, L.; Kjeldsted, E.; Hartmeyer, R.; Mygind, E.; Stevenson, M.P.; Quintana, D.S.; Bentsen, P. Effects of public green space on acute psychophysiological stress response: A systematic review and meta-analysis of the experimental and quasi-experimental evidence. Environ. Behav. 2019, 53, 001391651987337. [Google Scholar] [CrossRef]
- Haider, I.I.; Tiwana, F.; Tahir, S.M. Impact of the COVID-19 pandemic on adult mental health. Pak. J. Med. Sci 2020, 36, S90–S94. [Google Scholar] [CrossRef]
- Torales, J.; O′Higgins, M.; Castaldelli-Maia, J.M.; Ventriglio, A. The outbreak of COVID-19 coronavirus and its impact on global mental health. Int. J. Soc. Psychiatry 2020, 66, 317–320. [Google Scholar] [CrossRef]
- Chew, N.W.S.; Lee, G.K.H.; Tan, B.Y.Q.; Jing, M.; Goh, Y.; Ngiam, N.J.H.; Yeo, L.L.L.; Ahmad, A.; Ahmed Khan, F.; Napolean Shanmugam, G.; et al. A multinational, multicentre study on the psychological outcomes and associated physical symptoms amongst healthcare workers during COVID-19 outbreak. Brain Behav. Immun. 2020, 88, 559–565. [Google Scholar] [CrossRef] [PubMed]
- Zerbini, G.; Ebigbo, A.; Reicherts, P.; Kunz, M.; Messman, H. Psychosocial burden of healthcare professionals in times of COVID-19—A survey conducted at the University Hospital Augsburg. Ger. Med. Sci 2020, 18, Doc05. [Google Scholar] [CrossRef] [PubMed]
- Da Silva, F.R.; de Guerreiro, R.C.; de Andrade, H.A.; Stieler, E.; Silva, A.; de Mello, M.T. Does the compromised sleep and circadian disruption of night and shiftworkers make them highly vulnerable to 2019 coronavirus disease (COVID-19)? Chronobiol. Int. 2020, 37, 607–617. [Google Scholar] [CrossRef]
|Databases||Keyword Search Terms|
|CINAHL* Plus with Full-Text|
|(“greenspace” OR “green space” OR “green care” OR “greencare” OR “nature therap*” OR “wilderness therap*” OR “outdoors behavi*ral healthcare” OR “outdoors behavi*ral therap*” OR “forest bathing” OR “shinrin yoku” OR “shinrinyoku” OR “horticultur* therap*” OR “therapeutic horticulture” OR “green exercise” OR “ecotherap*” OR “conservation therap*” OR “care farm*” AND “cortisol”) AND intervention|
|Article & Location||Sample||Design||Intervention||Cortisol Measures||Results|
|Horticulture Therapy (HT)|
|Detweiler, Self |
|n = 24, n = 20|
(HT), n = 18
Mean age 46.4 yrs. (SD 11.9)
|Quasi-experimental, single arm||Setting(s): outdoor gardens (intervention), residential facility (control).|
Duration: 15, 60 min sessions over 3 weeks.
Collected by research team.
Measured at weeks 1, 2, and 3.
|No between groups comparison due to sampling inaccuracy.|
Nonsignificant downward cortisol trend over time.
|Han, Park |
|n = 28, n =14|
Mean age 80.1 yrs. (SD 2.9)
|Quasi-experimental, single arm||Setting(s): outdoor farm garden space (intervention), control setting unclear.|
Duration:10, 90 min sessions over 2 months.
Collected by research team
Measured at pre-test and post-test.
|Significant cortisol decrease over time (M 7.56 - M 3.80 (p < 0.05).|
No significant cortisol change in control group.
No significant between group difference.
|Ng, Sia |
|n = 59, n =29|
(treatment), n = 30 (waitlist control)
Mean age 67.1 yrs. (SD 4.31)
|Randomized wait-list controlled trial||Setting(s): outdoor parks, gardens, and nature reserves (intervention), waitlist (control)|
Duration: 15 hr. sessions for 3 months, repeated waitlist (6 months).
|Plasma cortisol (fasting, venous blood).|
Collected by research team.Time standardized
Measured at baseline, 3 months, and 6 months.
|No significant effects of time, group, or time × group interactions on plasma cortisol.|
|Van Den Berg and Custers |
|n = 30, n = 14 (gardening condition), n = 16 (reading condition)|
Mean age 57.6 (38 – 79) yrs.
|Quasi-experimental, single arm||Setting(s): personal outdoor and indoor gardens|
(intervention), reading (control) Duration: 30 min, “stressful task” for 25 additional minutes after baseline- before experimental activity.
Collected by research team.
Time not standardized.
Measured at baseline, pre-stressful task, post- stressful task, during condition, postcondition over 2-weeks.
|Stressful task non-significantly increased cortisol across both conditions compared to baseline. Significant decrease in cortisol post-stressor to post-condition in intervention (p < 0.001), and control group (p < 0.05). Significant condition to post-condition cortisol decrease in intervention group, (p < 0.05), but not control group.|
|Forest Bathing (FB) (Shinrin yoku) Active or Passive|
|Kobayashi, Song |
|n = 74|
Mean age 22.4 yrs. (SD. 1.8)
|Quasi-experimental crossover||Active (walking)|
Settings(s): 7 forests and urban centers, ratio unclear.
Duration: 25 min in an urban and forested site per participant (two site visits) over two days.
No time standardization
Measured pre-test and post-test.
|Significant interaction effect between setting X walking (p < 0.001).|
Significantly lower cortisol after walking in FB group than urban (p < 0.001). Significant pre-post decrease in cortisol (p < 0.001), but not urban walking.
|Lee, Park |
|n = 12|
Mean age 21.2 yrs. (SD – 0.9)
Setting(s): Forested region, urban street view
Duration: 15 min at each site over two days.
Measured baseline, pre- and post.
|Baseline cortisol significantly lower in FB group than urban (p < 0.05).|
Just before stimuli period, cortisol levels lower in the FB group than urban (p < 0.01). No significant differences in cortisol levels before and after stimuli period.
|Mao, Lan |
|n = 20, n = 10|
Mean age 20.79 yrs. (SD = 0.54)
Setting(s): Forest site
(intervention), city site (control). Duration: 1.5 h with 10 min rest twice a day for two days.
Collected by research team.
Measured at baseline, pre-test and post-test.
|Significantly lower cortisol in FB group than city-site post-intervention (p < 0.05). Exact levels for cortisol not reported.|
|Sung, Woo |
|n = 56, n = 28|
Mean age 66 yrs.
Forest therapy program (FTP).
Setting(s): two recreational forests. Duration: 3 days over 8 weeks.
Researchers collected samples. Time standardization not reported. Measured at baseline and 8 weeks postexposure.
|Significant pre to posttest difference, cortisol reduction larger in FB compared to the control group 0.03 (−0.02 to 0.08) vs. −0.03 (−0.11 to 0.01) μg/dL, (p < 0.05).|
|Greenspace Exposure (GE) Active or Passive|
|Beil and Hanes |
|n = 15 Mean age 42.3 (20 – 61) yrs.|
Hispanic White (NHW)
|Quasi experimental, multi-arm, cross-over||Passive (sitting). Setting(s): Very Natural, Mostly Natural, Mostly Built, Very Built. Duration: 20 min. per setting, 120 min total over one month.||Salivary cortisol.|
Participants self-collected salivary. samples with oral swabs. Time standardized per setting. Measured pre-test and post-test.
|Non-significant trend of decrease in cortisol post exposure in Very Natural and Mostly Natural settings, larger decreased in cortisol for the Mostly Built setting compared to the Very Built setting. No gender differences detected.|
|Grazuleviciene, Vencloviene |
|n = 20, n = 10|
Mean age 62.3 yrs. (SD – 12.6)
|Active (outdoor walking).|
Setting(s): green, forested park
(intervention), urban street (control). Duration: 30 min once a day for 7 days.
Affect (PANAS). Collector undisclosed. Time standardized. Measured 3 times per day: baseline, immediately following the exposure (1 min after walking in either environment), 60 min after the exposure.
|Significant correlation between negative affect (NA) and higher mean|
cortisol levels across all participants (p < 0.05). Cortisol levels not significantly correlated with positive affect (PA).
SBP and cortisol negatively associated (p < 0.1).
DBP and heart rate and cortisol slope over 7 days (p < 0.05).
No significant between group differences.
|Mokhtar, Abdul Aziz |
|n = 20, Mean age 23.1 yrs.|
|Quasi-experimental, single arm crossover||Active (walking)|
Settings: Urban greenspace (UGS) (intervention), city center (control). Duration: 20 min, twice in one day.
No time standardization.
Measured pre-test and post-test.
|Significantly greater decrease in cortisol pre to post-test in UGS than city group, (UGS: 0.89 ± 0.55, city: 2.33 ± 1.04, p < 0.05). Significantly increased cortisol in city group from pre: 1.75 ± 1.00 μg/dl, to post 2.33 ± 1.04 μg/dl (p < 0.05).|
|Olafsdottir, Cloke |
|n = 67, n = 20|
(nature setting), 30 (gym), 30 (TV) Mean age 24.4 yrs. (SD 2.61) 8.7% female
|Mixed-method factorial-multi-arm design.||Active (walking, exercising). Setting(s): Spruce forest (nature group), indoor gym (treadmill group), indoor laboratory (video group).|
Duration: 40 min in each condition over 76 min of data collection over 2 months.
No time standardization.Measured pre- post intervention and after The Socially
EvaluatedCold-Pressor Test (SECPT) was introduced.
|Cortisol significantly decreased from pre to post all groups (p < 0.001), returned to baseline after SECPT (p < 0.001). Significantly lower cortisol in nature group compared to the video group post-intervention (p = 0.046).|
Exact cortisol values not reported.No gender differences reported.
|Razani, Morshed |
|n= 154 (78 dyads),|
n = 50 (supported group), Parent mean age, 38.95 yrs. Child mean age 8.8 yrs. Parent 87% female
Child 49% female
|Quasi- experimental||Active (play), Setting(s): regional green park (supported park prescription group), no setting disclosed for independent park prescription group.|
Duration: 1–3 park outings once a month for 3 months.
|Salivary cortisol. Study staff collected samples. No time standardization. Measured baseline, 1 month and 3 months post intervention.||Cortisol decreased significantly from baseline M = 0.18, SD = 0.13, to 3 months, M = 0.12, SD = 0.07, (p = 0.0241), CI = 0.05, 0.65. All other analyses were non-significant.|
|Tyrväinen, Ojala |
|n = 77, Mean age 47.64 yrs. (SD 8.68)|
|Quasi-experimental, multi-arm crossover|| |
Active (walking) and passive (sitting). Setting(s): urban park, large urban woodland (interventions), city center (control). Duration: roughly 3-h per month over 10 months.
|Salivary cortisol. Collector undisclosed. No time standardization. Measured pre, during, and post-intervention.||Significant decrease in cortisol between pre and post exposure (p < 0.01) in all groups. No significant between groups differences.|
|Calogiuri, Evensen |
|n = 14, n = 6 (green exercise), n = 7 (gym). Mean age 49 years (SD – 8) Female 50%||Quasi-experimental single arm crossover|| |
Setting(s): Indoor gym (indoor group, control) and an outdoor forested park (outdoor group, intervention). Duration: 3 days over two-weeks with longitudinal follow-up at week 10.
|Serum cortisol. Time standardized: participants self-collected saliva forCAR upon awakening,|
15 min, 30 min.Nurses collected serum samples for CAR post exposure in the AM.Measured pre, post, 3 time points: baseline, afternoon and evening for 3 days.
|Significantly lower postexposure cortisol for intervention group compared to control (p = 0.04).|
No significant differences between groups found for CAR AUCG and serum cortisol. Non-significant higher AM cortisol levels and more rapid decrease 30 min. post AM than control.
|Outdoor Activity Programming (OAP)|
|Chang, Davidson |
|n = 33, n = 3|
(kayaking), n = 3
(backpacking), n = 4 (canoeing)
Mean age 20.67 yrs.
|Quasi experimental non-equivalent groups mixedmodel||Settings(s): field trip courses in three independent groups: canoeing (n = 9), backpacking (n = 16) kayaking (n = 8). Duration: 3 days over 2 weeks.||Salivary cortisol. Collected by research team. Not time standardized. Measured baseline, pretest and post-test.||Nonsignificant trend of decreasing cortisol over time in all groups.|
Significant decrease in cortisol from pre to posttest in all groups (p < 0.05)
No significant interaction or main effect of sex and time, or activity and time on cortisol.
|Dettweiler, Becker |
|n = 48|
Mean age 11.6 yrs.
38% female (forest)
|Quasi-experimental Prospective longitudinal single-arm||Setting(s): forested park (outdoor learning intervention) and indoor classroom|
Duration: 1 day each week for 9 months.
Measured at 8:30, 10:30 AM, and 12:30 PM, intervention day, 1 day per week, during school year
|Intervention group significant greater overall decline of cortisol than controls, (p < 0.01). Nonsignificant trend of intervention group lower cortisol levels in spring compared to other seasons (p = 0.05).|
|Niedermeier, Grafetstätter |
|n = 42, Mean age: 32 yrs. (SD 12).|
|Quasi experimental multi-arm crossover||Setting(s): Mountain region in a forest, indoor treadmill walking in a gym (interventions), computer room at a local University (control). Duration: 3 h in each condition over 14 days.||Salivary cortisol. Collector undisclosed. No time standardization. Measured pre-test and post-test.||Cortisol decreased significantly in all conditions over time (p < 0.001).|
Cortisol decreased more pre to post test in both intervention groups compared to control (p < 0.05).
No significant difference between intervention groups.
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