Across the U.S., college and university students exhibit high levels of stress, anxiety, depression, and other mental health issues. While counseling, medications and, in more severe cases, hospitalization are all appropriate treatments for such conditions, an increasing body of evidence has demonstrated that spending time in nature can provide tangible benefits for mental health and well-being. The aim of this study was to define a “dose” of time in nature that could be prescribed to college-age students, as a preventative and supportive mental health and well-being intervention. The specific objectives of this scoping review were thus: to define the minimum amount of time in nature that results in positive impact on mental health and well-being for college-aged students; to describe the types of engagement with nature that elicited the impact; and to describe and explore the most commonly used measure of effect pre- and post-time in nature.
This scoping review was conducted following the PRISMA-ScR Checklist. A review protocol was developed but not registered. Fourteen bibliographic databases were searched and all results were blindly screened using established inclusion criteria. All titles and abstracts were screened by at least two reviewers, a third being used as a tie-breaker if needed. Studies were included if: subjects were of average college age; they examined a treatment of time (hours or minutes) in nature; they examined change in measures of mental health and well-being pre- and post-exposure; they compared participants across at least two environments; the study was published in English or French; and if the study was <20 years old.
Initially, 11,799 titles were identified and once de-duplicated, 10,917 titles were screened. One hundred fifty-five papers were given full text reviews, of which 14 studies were included in this review. In summary, 13 of the 14 papers explicitly noted that the participants were college students. Two-thirds of the studies (n = 10) took place in Japan. One study took place in Sweden, and the remaining studies took place in the United States (n = 3). These studies show that, when contrasted with equal durations spent in urbanized settings, as little as 10 min of sitting or walking in a diverse array of natural settings significantly and positively impacted defined psychological and physiological markers of mental well-being for college-aged individuals. Within the included studies, 22 different measures were used to assess the effects of nature doses on mental health and well-being.
This review provides time-dose and activity-type evidence for programs looking to use time in nature as a preventative measure for stress and mental health strain, and also demonstrates opportunities in six specific foci for more research in this area.
American College Health Association (2017). American College Health Association-National College Health Assessment II: Reference Group Executive Summary. Available online at: https://www.acha.org/documents/ncha/NCHA-II_SPRING_2017_REFERENCE_GROUP_EXECUTIVE_SUMMARY.pdf (accessed August 29, 2019).
American Psychological Association (2019a). Stress Effects on the Body. Available online at: http://www.apa.org/helpcenter/stress-body.aspx (accessed August 23, 2019).
American Psychological Association (2019b). The State-Trait Anxiety Inventory (Stai). Available online at: https://www.apa.org/pi/about/publications/caregivers/practice-settings/assessment/tools/trait-state.aspx (accessed August 23, 2019).
Antonelli, M., Barbieri, G., and Donelli, D. (2019). Effects of forest bathing (shinrin-yoku) on levels of cortisol as a stress biomarker: a systematic review and meta-analysis. Int. J. Biometeorol. 63:1117. doi: 10.1007/s00484-019-01717-x
Association of University College Counseling Center Directors Annual Survey (2017). Available online at: https://www.aucccd.org/assets/2017%20aucccd%20survey-public-apr17.pdf (accessed September 12, 2019).
Benham, G., Nash, M. R., and Baldwin, D. R. (2009). A comparison of changes in secretory immunoglobulin a following a stress-inducing and stress-reducing task. Stress Health 25, 81–90. doi: 10.1002/smi.1225
Bratman, G. N., Anderson, C. B., Berman, M. G., Cochran, B., de Vries, S., Flanders, J., et al. (2019). Nature and mental health: an ecosystem service perspective. Sci. Adv. 5, 1–14. doi: 10.1126/sciadv.aax0903
Bratman, G. N., Hamilton, J. P., and Daily, G. C. (2012). The impacts of nature experience on human cognitive function and mental health. Ann. N. Y. Acad. Sci. 1249, 118–136. doi: 10.1111/j.1749-6632.2011.06400.x
Cohen, S. (1994). Perceived Stress Scale – Mind Garden. Available online at: https://www.mindgarden.com/132-perceived-stress-scale (accessed March 9, 2019).
Cox, D. T. C., Shanahan, D. F., Hudson, H. L., Plummer, K. E., Siriwardena, G. M., Fuller, R. A., et al. (2017). Doses of neighborhood nature: the benefits for mental health of living with nature. Bioscience 67, 147–155. doi: 10.1093/biosci/biw173
Crawford, J. R., and Henry, J. D. (2010). The positive and negative affect schedule (panas): Construct validity, measurement properties and normative data in a large non-clinical sample. Br. J. Clin. Psychol. 43, 245–265. doi: 10.1348/0144665031752934
Crouse, D. L., Pinault, L., Balram, A., Hystad, P., Peters, P. A., Chen, H., et al. (2017). Urban greenness and mortality in Canada’s largest cities: a national cohort study. Lancet Planet. Health 1:e289–e297. doi: 10.1016/S2542-5196(17)30118-3
De Young, R. (2016). Necker Cube Test Introduction. Available online at: http://seas.umich.edu/eplab/demos/nt0/neckerintro.html (accessed March 9, 2019).
Derogatis, L. R. (1994). Symptom Checklist-90-Revised. Available online at: https://www.pearsonclinical.com/psychology/products/100000645/symptom-checklist-90-revised-scl-90-r.html-tab-details (accessed March 9, 2019).
Eagan, K., Stolzenberg, E. B., Bates, A. K., Aragon, M. C., Suchard, M. R., and Rios-Aguilar, C. (2015). The American Freshman: National Norms Fall 2015. Los Angeles, CA: Higher Education Research Institute; UCLA.
Fan, Y., Tang, Y., Lu, Q., Feng, S., Yu, Q., Sui, D., et al. (2008). Dynamic changes in salivary cortisol and secretory immunoglobulin a response to acute stress. Stress Health 25, 189–194. doi: 10.1002/smi.1239
Fong, K., Hart, J. E., and James, P. (2018). A review of epidemiologic studies on greenness and health: updated literature through 2017. Curr. Environ. Health Rep. 5, 77–87. doi: 10.1007/s40572-018-0179-y
Frumkin, H., Bratman, G. N., Breslow, S. J., Cochran, B., Kahn, P. H., Lawler, J. J., et al. (2017). Nature contact and human health: a research agenda. Environ. Health Perspect. 125:075001. doi: 10.1289/EHP1663
Gallagher, R. P. (2015). National Survey of College Counseling Centers 2014. Available online at: http://d-scholarship.pitt.edu/28178/ (accessed February 14, 2019).
Hansen, M. M., Jones, R., and Tocchini, K. (2017). Shinrin-Yoku (forest bathing) and nature therapy: a state-of-the-art review. Int. J. Environ. Res. Public Health 14:E851. doi: 10.3390/ijerph14080851
Hartig, T., Evans, G. W., Jamner, L. D., Davis, D. S., and Gärling, T. (2003). Tracking restoration in natural and urban field settings. J. Environ. Psychol. 23, 109–123. doi: 10.1016/S0272-4944(02)00109-3
Heuchert, J, and McNair, D. M. (2019). Poms 2® – Profile of Mood States Second Edition® | Multi Health Systems (mhs inc.). Available online at: https://www.mhs.com/MHS-Assessment?prodname=poms2 (accessed April 3, 2019).
Hunter, M. C., Gillespie, B. W., and Chen, S. Y.-P. (2019). Urban nature experiences reduce stress in the context of daily life based on salivary biomarkers. Front. Psychol. 10:722, doi: 10.3389/fpsyg.2019.00722
James, P., Hart, J. E., Banay, R. F., and Laden, F. (2016). Exposure to greenness and mortality in a nationwide prospective cohort study of women. Environ. Health Perspect. 124, 1344–1352. doi: 10.1289/ehp.1510363
Johansson, M., Hartig, T., and Staats, H. (2011). Psychological benefits of walking: moderation by company and outdoor environment. Appl. Psychol. Health Well Being 3, 261–280. doi: 10.1111/j.1758-0854.2011.01051.x
Lau, S. Y., and Yang, F. (2009). Introducing healing gardens into a compact university campus: design natural spaces to create healthy and sustainable campuses. Landsc. Res. 34, 55–81. doi: 10.1080/01426390801981720
Lee, J., Park, B.-J., Tsunetsugu, Y., Kagawa, T., and Miyazaki, Y. (2009). Restorative effects of viewing real forest landscapes, based on a comparison with urban landscapes. Scand. J. Forest Res. 24, 227–234. doi: 10.1080/02827580902903341
Lee, J.-Y., Park, K.-T., Lee, M.-S., Park, B.-J., Ku, J.-H., Lee, J.-W., et al. (2011). Evidence-based field research on health benefits of urban green area. J. Korean Inst. Landsc. Archit. 39, 111–118. doi: 10.9715/KILA.2011.39.5.111
Mackay, C., Cox, T., Burrows, G., and Lazzerini, T. (1978). An inventory for the measurement of self-reported stress and arousal. Br. J. Soc. Clin. Psychol. 17, 283–284. doi: 10.1111/j.2044-8260.1978.tb00280.x
Maller, C., Townsend, M., Pryor, A., Brown, P., and St Leger, L. (2006). Healthy nature healthy people: ‘contact with nature’ as an upstream health promotion intervention for populations. Health Promot. Int. 21, 45–54. doi: 10.1093/heapro/dai032
Mayer, S. F., McPherson, F. C., Bruehlman-Senecal, E., and Dolliver, K. (2009). Why is nature beneficial? The role of connectedness to nature. Environ. Behav. 41, 607–643. doi: 10.1177/0013916508319745
Park, B.-J., Tsunetsugu, Y., Ishii, H., Furuhashi, S., Hirano, H., Kagawa, T., et al. (2008). Physiological effects of shinrin-yoku (taking in the atmosphere of the forest) in a mixed forest in Shinano Town, Japan. Scand. J. Forest Res. 23, 278–283. doi: 10.1080/02827580802055978
Park, B.-J., Tsunetsugu, Y., Kasetani, T., Hirano, H., Kagawa, T., Sato, M., et al. (2007). Physiological effects of shinrin-yoku (taking in the atmosphere of the forest)—using salivary cortisol and cerebral activity as indicators. J. Physiol. Anthropol. 26, 123–128. doi: 10.2114/jpa2.26.123
Park, B.-J., Tsunetsugu, Y., Kasetani, T., Kagawa, T., and Miyazaki, Y. (2010). The physiological effects of shinrin-yoku (taking in the forest atmosphere or forest bathing): evidence from field experiments in 24 forests across Japan. Environ. Health Prevent. Med. 15, 18–26. doi: 10.1007/s12199-009-0086-9
Razani, N., Morshed, S., Kohn, M. A., Wells, N. M., Thompson, D., Alqassari, M., et al. (2018). Effect of park prescriptions with and without group visits to parks on stress reduction in low-income parents: SHINE randomized trial. PLoS ONE 13:e0192921. doi: 10.1371/journal.pone.0192921
Scott, B., Brandberg, M., and OÖhman, A. (2001). Measuring the negative mood component of stress experiences: description and psychometric properties of a short adjective check–list of stress responses. Scand. J. Psychol. 42, 1–7. doi: 10.1111/1467-9450.00208
Song, C., Ikei, H., Igarashi, M., Miwa, M., Takagaki, M., and Miyazaki, Y. (2014). Physiological and psychological responses of young males during spring-time walks in urban parks. J. Physiol. Anthropol. 33:8. doi: 10.1186/1880-6805-33-8
Song, C., Ikei, H., Igarashi, M., Takagaki, M., and Miyazaki, Y. (2015). Physiological and psychological effects of a walk in urban parks in fall. Int. J. Environ. Res. Public Health 12, 14216–14228. doi: 10.3390/ijerph121114216
Song, C., Joung, D., Ikei, H., Igarashi, M., Aga, M., Park, B.-J., et al. (2013). Physiological and psychological effects of walking on young males in urban parks in winter. J. Physiol. Anthropol. 32:18. doi: 10.1186/1880-6805-32-18
The Chronicle of Higher Education (2017). The Student Centered University: Pressures and Challenges Faced by College Presidents and Student Affairs Leaders. Available online at: http://results.chronicle.com/SCU-2017-O (accessed April 9, 2019).
Trapnell, P. D., and Campbell, J. D. (1999). Private self-consciousness and the five-factor model of personality: distinguishing rumination from reflection. J. Pers. Soc. Psychol. 76, 284–304. doi: 10.1037//0022-35184.108.40.2064
Tricco, A. C., Lillie, E., Zarin, W., O’Brien, K. K., Colquhoun, H., Levac, D., et al. (2018). Prisma extension for scoping reviews (prisma-scr): checklist and explanation. Ann. Intern. Med. 169, 467–473. doi: 10.7326/M18-0850
Tsunetsugu, Y., Lee, J., Park, B.-J., Tyrväinen, L., Kagawa, T., and Miyazaki, Y. (2013). Physiological and psychological effects of viewing urban forest landscapes assessed by multiple measurements. Landsc. Urban Plan. 113, 90–93. doi: 10.1016/j.landurbplan.2013.01.014
Tsunetsugu, Y., Park, B.-J., Ishii, H., Hirano, H., Kagawa, T., and Miyazaki, Y. (2007). Physiological effects of shinrin-yoku (taking in the atmosphere of the forest) in an old-growth broadleaf forest in Yamagata Prefecture, Japan. J. Physiol. Anthropol. 26, 135–142. doi: 10.2114/jpa2.26.135
Ulrich, R. S., Simons, R. F., Losito, B. D., Fiorito, E., Miles, M. A., and Zelson, M. (1991). Stress recovery during exposure to natural and urban environments. J. Environ. Psychol. 11, 201–230. doi: 10.1016/S0272-4944(05)80184-7
USA Today (2017). More and More Students Need Mental Health Services. But Colleges Struggle to Keep Up. Available online at: http://college.usatoday.com/2017/05/04/more-and-more-students-need-mental-health-services-but-colleges-struggle-to-keep-up/ (accessed May 7, 2019).
Van den Berg, A. E. (2008). “Restorative effects of nature: towards a neurobiological approach,” in Proceedings of the Proceedings of the 9th Int Congress of Physiological Anthropology (Delft, 132–138.
Van den Berg, A. E., Hartig, T., and Staats, H. (2007). Preference for nature in urbanized societies: stress, restoration, and the pursuit of sustainability. J. Soc. Issues 63, 79–96. doi: 10.1111/j.1540-4560.2007.00497.x
Watson, D., Clark, L. A., and Tellegen, A. (1988). Development and validation of brief measures of positive and negative affect: the panas scales. J. Pers. Soc. Psychol. 54, 1063–1070. doi: 10.1037//0022-35220.127.116.113
White, M. P., Alcock, I., Grellier, J., Wheeler, B. W., Hartig, T., Warber, S. L., et al. (2019). Spending at least 120 minutes a week in nature is associated with good health and wellbeing. Nat. Sci. Rep. 9:7730. doi: 10.1038/s41598-019-44097-3
Williams, R., and Leahy, A. (2018). Ranking of National Higher Education Systems. Melbourne, VIC: Melbourne Institute of Applied Economic and Social Research. Available online at: https://universitas21.com/sites/default/files/2018-05/U21_Rankings%20Report_0418_FULL_LR%20%281%29.pdf (accessed June 11, 2019).
World Health Organization (2017). Mental Health Day 2017. Available online at: https://www.who.int/mental_health/world-mental-health-day/2017/en/ (accessed June 11, 2019).