Evidence base for the health benefits behind children spending time outside
Children should spend time outdoors due to direct physical and mental health benefits - specifically with effects on their vision - supported by a growing body of evidence.
Physical benefits for children from spending time outside include a multitude of factors including improved motor skills, reduced risk of obesity, and reduced risk of developing myopia (short-sightedness). Systematic reviews demonstrate that outdoor environments and green spaces consistently promote higher levels of physical activity in children compared to indoor or built environments, with objective measures confirming these effects.[1-3] There is also evidence for improved vision and reduced risk of myopia (short-sightedness) with increased outdoor time - see second part of article.[4] The American Academy of Pediatrics specifically encourages daily outdoor play for these reasons.[5]
Mental health effects are substantial. Exposure to nature and green spaces is associated with reduced stress, lower blood pressure, and improved cortisol profiles, indicating physiological stress reduction.[5-7] Multiple systematic reviews and meta-analyses show that time outdoors is linked to reduced behavioural problems, including reductions in inattention, anxiety, and depression.[1][8-11] A large cohort study found that children living in areas with more green space had nearly half the rate of mental health diagnoses later , even after adjusting for confounders.[5]
Cognitive and neuropsychological development also benefit from outdoor time, with evidence for improved attention, working memory, self-regulation, and academic performance, although findings are mixed and further longitudinal research is needed.[2][5-6][12]
How long should parents try and spend time outdoors with their children?
“The optimal amount of time children should spend outside per day to achieve physical and mental health benefits is at least 60 minutes of outdoor time daily”
as endorsed by the United States Department of Health and Human Services and the American Academy of Pediatrics.[13-15]
For preschool-aged children (3–5 years), the recommendation is to be physically active throughout the day, with a target increasing to at least 3 hours of activity, including outdoor play, spread across the day.[1-2][4-5] Evidence from large cohort and accelerometer studies indicates that outdoor play is a key driver for meeting these physical activity guidelines, and that daily outdoor time is associated with improved physical performance, reduced sedentary behaviour, and better psychosocial outcomes.[13-15].
Daily outdoor time is recommended rather than intermittent or less frequent exposure, as regularity supports habit formation, maximizes cumulative benefits, and aligns with developmental needs for physical and mental health.[13-15]
“Daily outdoor time supports habit formation” - The American Academy of Pediatrics
The American Academy of Pediatrics specifically encourages pediatricians to promote daily outdoor play and to protect unstructured outdoor time for all children.[14]
What is the evidence for the link between spending time outside and myopia (short-sightedness)?
There is a well-established association between increased time spent indoors and a higher risk of developing myopia (short-sightedness) in children. The American Academy of Ophthalmology states that reduced outdoor exposure is a key environmental factor contributing to the rising prevalence of myopia, particularly in urbanised settings where children spend more time indoors and less time in natural light. The rationale is that outdoor light exposure may play a role in normal eye growth and development, thereby reducing the risk of myopia onset, although the exact biological mechanisms remain under investigation.[16]
School-based randomized trials demonstrate that
“Increasing daily outdoor time by 40–80 minutes reduces the incidence of myopia by 11–16% over two years”
with objective monitoring confirming that children who spend > 2 hours outdoors per day experience the greatest protective effect against myopia onset and progression.[17] The protective effect is dose-dependent, with higher cumulative outdoor light exposure conferring greater benefit.
Epidemiological studies and meta-analyses consistently show that each additional hour spent outdoors per day is associated with a 13% reduction in the odds of developing myopia.[18] The effect is independent of genetic predisposition and near-work activities, and is most pronounced in children aged 3–9 years, where increased outdoor time during these ages is associated with a lower risk of incident myopia in later childhood.[19] The mechanism is thought to involve higher ambient light exposure outdoors, which may regulate dopamine release in the retina —a key driver of myopia.[20]
Conversely, studies conducted during periods of enforced indoor confinement, such as
“COVID-19 lockdowns, have documented a marked increase in myopia prevalence and progression among children”
particularly those with low baseline outdoor activity.[21] Multivariate analyses confirm that
“Less frequent outdoor activity (once a week vs. twice a week or more) is associated with a fourfold increase in myopia risk.”[22]
Longitudinal data further support that increased time spent indoors, especially for near-work or screen-based activities, is associated with greater myopic shift (risk for myopia), even after adjusting for parental myopia and socioeconomic status.[23]
In summary, the medical literature robustly supports that increased time spent indoors is a modifiable risk factor for the development and progression of myopia in children, with regular, daily outdoor exposure—ideally exceeding 2 hours —providing significant protective effects.[23]
References
1.Nature and Children's Health: A Systematic Review. Fyfe-Johnson AL, Hazlehurst MF, Perrins SP, et al. Pediatrics. 2021;148(4):e2020049155. doi:10.1542/peds.2020-049155.
2.Mental, Physical and Social Health Benefits of Immersive Nature-Experience for Children and Adolescents: A Systematic Review and Quality Assessment of the Evidence. Mygind L, Kjeldsted E, Hartmeyer R, et al. Health & Place. 2019;58:102136. doi:10.1016/j.healthplace.2019.05.014.
3.Landscapes of Becoming Social: A Systematic Review of Evidence for Associations and Pathways Between Interactions With Nature and Socioemotional Development in Children. Mygind L, Kurtzhals M, Nowell C, et al. Environment International. 2021;146:106238. doi:10.1016/j.envint.2020.106238. Leading Journal
4. Determinants of Outdoor Time in Children and Youth: A Systematic Review of Longitudinal and Intervention Studies. Larouche R, Kleinfeld M, Charles Rodriguez U, et al. International Journal of Environmental Research and Public Health. 2023;20(2):1328. oi:10.3390/ijerph20021328.
5. The Built Environment and Pediatric Health. Bole A, Bernstein A, White MJ. Pediatrics. 2023;:e2023064773. doi:10.1542/peds.2023-064773. Practice Guideline
6. Associations Between Nature Exposure and Health: A Review of the Evidence. Jimenez MP, DeVille NV, Elliott EG, et al. International Journal of Environmental Research and Public Health. 2021;18(9):4790. doi:10.3390/ijerph18094790.
7. Nature Experience and Mental Health in Children-Theoretical Approaches and Selected Empirical Findings. Gebhard U. Bundesgesundheitsblatt, Gesundheitsforschung, Gesundheitsschutz. 2023;66(7):803-810. doi:10.1007/s00103-023-03729-w.
8. Effect of Nature on the Mental Health and Well-Being of Children and Adolescents: Meta-Review. Lomax T, Butler J, Cipriani A, Singh I. The British Journal of Psychiatry : The Journal of Mental Science. 2024;225(3):401-409. doi:10.1192/bjp.2024.109.
9. A Nature-Based Intervention and Mental Health of Schoolchildren: A Cluster Randomized Clinical Trial. Loose T, Fuoco J, Malboeuf-Hurtubise C, et al. JAMA Network Open. 2024;7(11):e2444824. doi:10.1001/jamanetworkopen.2024.44824.
10. Impact of Green Space Exposure on Children's and Adolescents' Mental Health: A Systematic Review. Vanaken GJ, Danckaerts M. International Journal of Environmental Research and Public Health. 2018;15(12):E2668. doi:10.3390/ijerph15122668.
11. Mental Health Benefits of Interactions With Nature in Children and Teenagers: A Systematic Review. Tillmann S, Tobin D, Avison W, Gilliland J. Journal of Epidemiology and Community Health. 2018;72(10):958-966. doi:10.1136/jech-2018-210436.
12. Does Exposure to Greenness Improve Children's Neuropsychological Development and Mental Health? A Navigation Guide Systematic Review of Observational Evidence for Associations. Luque-García L, Corrales A, Lertxundi A, Díaz S, Ibarluzea J. Environmental Research. 2022;206:112599. doi:10.1016/j.envres.2021.112599.
13. Physical Activity Assessment and Counseling in Pediatric Clinical Settings. Lobelo F, Muth ND, Hanson S, Nemeth BA. Pediatrics. 2020;145(3):e20193992. doi:10.1542/peds.2019-3992. Practice Guideline
14. The Physical Activity Guidelines for Americans. Piercy KL, Troiano RP, Ballard RM, et al. Jama. 2018;320(19):2020-2028. doi:10.1001/jama.2018.14854. Practice Guideline
15. The Role of the Pediatrician in the Promotion of Healthy, Active Living. Muth ND, Bolling C, Hannon T, Sharifi M. Pediatrics. 2024;153(3):e2023065480. doi:10.1542/peds.2023-065480.
16. Reducing the Global Burden of Myopia by Delaying the Onset of Myopia and Reducing Myopic Progression in Children: The Academy's Task Force on Myopia. Modjtahedi BS, Abbott RL, Fong DS, Lum F, Tan D. Ophthalmology. 2021;128(6):816-826. doi:10.1016/j.ophtha.2020.10.040. Practice Guideline
17. Time Outdoors in Reducing Myopia: A School-Based Cluster Randomized Trial With Objective Monitoring of Outdoor Time and Light Intensity. He X, Sankaridurg P, Wang J, et al. Ophthalmology. 2022;129(11):1245-1254. doi:10.1016/j.ophtha.2022.06.024.
18. The Association Between Time Spent Outdoors and Myopia in Children and Adolescents: A Systematic Review and Meta-Analysis. Sherwin JC, Reacher MH, Keogh RH, et al. Ophthalmology. 2012;119(10):2141-51. doi:10.1016/j.ophtha.2012.04.020.
19. Time Outdoors at Specific Ages During Early Childhood and the Risk of Incident Myopia. Shah RL, Huang Y, Guggenheim JA, Williams C. Investigative Ophthalmology & Visual Science. 2017;58(2):1158-1166. doi:10.1167/iovs.16-20894.
20. Impact of Various Types of Near Work and Time Spent Outdoors at Different Times of Day on Visual Acuity and Refractive Error Among Chinese School-Going Children. Guan H, Yu NN, Wang H, et al. PloS One. 2019;14(4):e0215827. doi:10.1371/journal.pone.0215827.
21. Prevalence of Myopia in Children Before, During, and After COVID-19 Restrictions in Hong Kong. Zhang XJ, Zhang Y, Kam KW, et al. JAMA Network Open. 2023;6(3):e234080.doi:10.1001/jamanetworkopen.2023.4080.
22. The Relationship Between Myopia and Near Work, Time Outdoors and Socioeconomic Status in Children and Adolescents. Philipp D, Vogel M, Brandt M, et al. BMC Public Health. 2022;22(1):2058. doi:10.1186/s12889-022-14377-1.
23. Myopic Shift and Outdoor Activity Among Primary School Children: One-Year Follow-Up Study in Beijing. Guo Y, Liu LJ, Xu L, et al. PloS One. 2013;8(9):e75260. doi:10.1371/journal.pone.0075260.
