Stress recovery · Evidence identifiers checked 2026-10-11 · Version 0.1.0 · Not yet reviewed by a clinician
How Much Nature Is Enough: The Dose Evidence
What the 120-minute finding actually says, how long a single visit needs to be, and what the randomised trials found about structured nature activities.
The nature-and-health literature has a usable dose finding and a set of caveats. A nationally representative cross-sectional survey of 19,806 adults in England found that compared with no nature contact, people reporting at least 120 minutes in nature in the past week were more likely to report good health (OR 1.59 for 120 to 179 minutes) and high well-being (OR 1.23), that associations peaked at 200 to 300 minutes a week, and that it did not matter whether the time came in one visit or several. A within-person study of 36 urban dwellers found a nature experience lowered salivary cortisol by 21.3% per hour beyond its normal daily decline, with the benefit per minute greatest between 20 and 30 minutes and smaller added gains after that. A systematic review and meta-analysis of 50 studies found structured nature-based activities in randomised trials improved positive affect (0.95, 95% CI 0.59 to 1.31) and reduced negative affect (-0.52, 95% CI -0.77 to -0.26), with less evidence for physical health benefits, and that the most effective programmes ran 8 to 12 weeks with sessions of 20 to 90 minutes. A 90-minute nature walk reduced self-reported rumination and activity in a brain region linked to rumination, while an urban walk did not. And a meta-analysis of forest bathing found salivary cortisol lower in forest than urban groups (MD -0.05 ug/dL) with high heterogeneity.
Not medical advice. This is a plain-language summary of published research for generally healthy adults. It is AI-drafted, has not been reviewed by a clinician, and nothing here diagnoses or treats anything.
What the evidence supports
Compared with no nature contact, people reporting at least 120 minutes in nature in the past week were more likely to report good health (OR 1.59 for 120-179 minutes) and high well-being (OR 1.23); associations peaked at 200 to 300 minutes a week and it did not matter whether time came in one visit or several. c-01
A nature experience lowered salivary cortisol by 21.3% per hour beyond its normal daily decline, with the benefit per minute greatest between 20 and 30 minutes and smaller added gains after that. c-02
In randomised trials, structured nature-based activities improved positive affect (0.95, 95% CI 0.59 to 1.31) and reduced negative affect (-0.52, 95% CI -0.77 to -0.26), with less evidence for physical health benefits; the most effective programmes ran 8 to 12 weeks with sessions of 20 to 90 minutes. c-03
A 90-minute walk in a natural setting reduced self-reported rumination and activity in a brain region linked to rumination, while a 90-minute urban walk did not. c-04
One next step: Get 120 minutes of nature into this week in whatever chunks fit, and make one of them 20 to 30 minutes long.
The short version
The 120-minute finding
A nationally representative survey of 19,806 adults in England found that compared with no nature contact, people reporting at least 120 minutes in nature in the past week were more likely to report good health (OR 1.59 at 120 to 179 minutes) and high well-being (OR 1.23). Associations peaked at 200 to 300 minutes a week. Crucially for planning, it did not matter whether the time came in one visit or several.
It is cross-sectional and self-reported, so it cannot show that nature caused the difference. But as a target it is unusually usable: 120 minutes a week, in any arrangement, is roughly two hours.
A within-person study of 36 urban dwellers found a nature experience lowered salivary cortisol by 21.3% per hour beyond the normal daily decline, and that the benefit per minute was greatest between 20 and 30 minutes with smaller added gains after that. That is a practical answer to the question of whether a short walk counts: yes, and about 20 to 30 minutes is where the return per minute is best.
A systematic review and meta-analysis of 50 studies found structured nature-based activities improved positive affect (0.95) and reduced negative affect (-0.52) in randomised trials, with less evidence for physical health benefits, and that the most effective programmes ran 8 to 12 weeks with sessions of 20 to 90 minutes. So there is a difference between casual time outdoors and a programme, and the programme evidence is about affect rather than physical health.
An experiment adds the setting question: a 90-minute walk in a natural setting reduced self-reported rumination and activity in the subgenual prefrontal cortex, a region linked to rumination, while a 90-minute urban walk did not. A meta-analysis of forest bathing found salivary cortisol lower in forest than urban groups (MD -0.05 ug/dL) with high heterogeneity, and nearly all studies reporting lower cortisol after forest exposure.
Aim for about two hours a week in whatever green space you can reach, split however suits you, with at least one visit of 20 to 30 minutes. Leave the phone where it does not pull you back into work. If low mood is persistent and you want more than a walk, the intervention evidence supports structured programmes of 8 to 12 weeks rather than occasional outings, and those are usually group-based, which adds a social component.
None of this is treatment. The randomised evidence supports effects on affect, not on physical health outcomes, and the dose finding is an association.
Three common beliefs, checked against the surveys and meta-analyses behind this page.
Pick what you believe first; the evidence answer is revealed after, so you can see where your assumption and the studies part company. Nothing is scored against you.
Short time outdoors does not count.
Associations with good health and well-being appeared at 120 minutes a week and did not depend on whether the time came in one visit or several. A within-person study found the benefit per minute was greatest between 20 and 30 minutes.
A 90-minute walk in a natural setting reduced self-reported rumination and subgenual prefrontal cortex activity, while a 90-minute urban walk did not. A forest bathing meta-analysis found lower cortisol after forest than urban exposure.
Time in nature is proven to improve physical health.
Mixed. The dose association is cross-sectional and self-reported, and the meta-analysis of randomised trials found effects on positive and negative affect with less evidence for physical health benefits.
A guided group, a conservation volunteering slot or a walking programme. The intervention evidence is stronger for this than for casual outings, and the group setting adds a social component.
A fixed weekly commitment for two to three months.
Leave the phone in a pocket on silent, or at home for short visits. The measured comparison was a walk in nature against a walk in a city, so removing work and feed input keeps the conditions closer to what was tested.
Safety and navigation; carry it silenced if you need it.
Total your nature minutes for the week, compare them with the 120-minute finding, and print the schedule that fits.
Free: weekly total with visit breakdown; comparison with the 120-minute threshold; text export and print; all citations and cautions Plus (optional, $5 one-time, price being tested): calendar (.ics) visit reminders; unlimited share images; share card without the 'Made with CortexLit' footer Works offline. No account. Every source and caution stays free.
Design one visit at the length with the best return per minute, with a location and a phone rule, and print it.
Free: full visit plan with phone rule; weekly total; text export and print; all citations and cautions Plus (optional, $5 one-time, price being tested): calendar (.ics) visit reminders; unlimited share images; share card without the 'Made with CortexLit' footer Works offline. No account. Every source and caution stays free.
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Evidence cards
Each card links a claim from this page to its sources. "Certainty" is our informal editorial judgement of how sure we can be, based on study design, size, consistency, and how closely it fits everyday life. Sources were weighted by type: Cochrane and systematic reviews 1.0, guidelines 0.9, randomized trials 0.8, observational studies 0.5, lab, mechanism or animal work 0.2. That ranking isn't the same thing as certainty.
c-01 In a nationally representative cross-sectional survey of 19,806 adults in England, compared with no nature contact, people reporting at least 120 minutes of recreational nature contact in the past week were more likely to report good health (OR 1.59 for 120 to 179 minutes) and high well-being (OR 1.23). Associations peaked at 200 to 300 minutes a week, and it did not matter whether the time came in one visit or several.
Certainty: lowObservational (association only)
Who was studied, what was found, and the limits
Who: 19,806 adults in a nationally representative English survey Measured: Self-reported health and well-being against weekly recreational nature contact Finding: OR 1.59 for good health at 120-179 minutes, OR 1.23 for high well-being; peak at 200-300 minutes
Why this certainty: A large nationally representative survey with a clear threshold and a reported plateau. (Informal editorial assessment, not a formal GRADE rating.)
Limits: Cross-sectional and self-reported; healthier and wealthier people may both spend more time in nature. Applies to: A weekly target, and the fact that it can be split up.
Identifier carried over from the 2026-10-11 abstract-level verification batch; not re-queried in this run. Source record
c-02 In a within-person study of 36 urban dwellers asked to spend at least 10 minutes in a place that felt like nature, a nature experience lowered salivary cortisol by 21.3% per hour beyond its normal daily decline. The benefit per minute was greatest between 20 and 30 minutes, with smaller added gains after that.
Certainty: lowHuman trials (cause and effect)
Who was studied, what was found, and the limits
Who: 36 urban dwellers studied within-person in daily life Measured: Salivary cortisol during and after a nature experience Finding: Cortisol 21.3% per hour lower beyond the normal decline; greatest benefit per minute at 20-30 minutes
Why this certainty: A within-person design with a biomarker, so each person acts as their own comparison. (Informal editorial assessment, not a formal GRADE rating.)
Limits: 36 participants; cortisol is a short-term marker; the place had to feel like nature to the participant. Applies to: How long a single visit needs to be to be worth taking.
Identifier carried over from the 2026-10-11 abstract-level verification batch; not re-queried in this run. Source record
c-03 In a systematic review and meta-analysis of 50 studies of outdoor nature-based interventions for community-dwelling adults, randomised trials showed structured nature-based activities improved positive affect (0.95, 95% CI 0.59 to 1.31) and reduced negative affect (-0.52, 95% CI -0.77 to -0.26). There was less evidence for physical health benefits. The most effective programmes ran 8 to 12 weeks with sessions of 20 to 90 minutes.
Certainty: moderateHuman trials (cause and effect)
Who was studied, what was found, and the limits
Who: Community-dwelling adults in 50 studies of nature-based interventions Measured: Positive and negative affect and physical health outcomes Finding: Positive affect +0.95, negative affect -0.52 in randomised trials; best programmes 8-12 weeks, 20-90 minute sessions
Why this certainty: A systematic review and meta-analysis restricted to randomised trials for the affect outcomes, weighted 1.0 in this scheme. (Informal editorial assessment, not a formal GRADE rating.)
Limits: Affect outcomes rather than clinical ones; less evidence for physical health; programmes were structured and often group-based. Applies to: What a structured programme buys beyond casual time outdoors.
Identifier carried over from the 2026-10-11 abstract-level verification batch; not re-queried in this run. Source record
c-04 In an experiment with healthy participants, a 90-minute walk in a natural setting reduced self-reported rumination and activity in the subgenual prefrontal cortex, a brain region linked to rumination, while a 90-minute walk in an urban setting did not.
Certainty: lowHuman trials (cause and effect)
Who was studied, what was found, and the limits
Who: Healthy participants assigned to a nature or an urban 90-minute walk Measured: Self-reported rumination and subgenual prefrontal cortex activity Finding: Nature walk reduced rumination and sgPFC activity; urban walk did not
Why this certainty: A randomised comparison with a neuroimaging measure alongside self-report. (Informal editorial assessment, not a formal GRADE rating.)
Limits: Small sample; a single 90-minute walk; healthy young participants. Applies to: Why the setting appears to matter, not only the walking.
Identifier carried over from the 2026-10-11 abstract-level verification batch; not re-queried in this run. Source record
c-05 In a systematic review of 22 studies and meta-analysis of 8, salivary cortisol was lower in forest groups than urban groups after the intervention (MD -0.05 ug/dL, 95% CI -0.06 to -0.04), with high heterogeneity; nearly all studies reported lower cortisol after forest exposure.
Certainty: moderateHuman trials (cause and effect)
Who was studied, what was found, and the limits
Who: Participants in 22 reviewed studies, 8 pooled, comparing forest with urban exposure Measured: Salivary cortisol Finding: MD -0.05 ug/dL lower after forest exposure, with high heterogeneity
Why this certainty: A systematic review and meta-analysis, weighted 1.0, with consistent direction across nearly all studies. (Informal editorial assessment, not a formal GRADE rating.)
Limits: High heterogeneity; small absolute cortisol difference; forest settings differ widely. Applies to: Whether forest-specific exposure adds anything beyond ordinary green space.
Identifier carried over from the 2026-10-11 abstract-level verification batch; not re-queried in this run. Source record
c-06 The 120-minute finding is cross-sectional and self-reported, so it cannot show that nature contact caused better health, and the intervention evidence supports effects on affect rather than on physical health outcomes, so the honest use of this evidence is as a target for mood and stress rather than a health treatment.
Certainty: moderateEvidence gap
Who was studied, what was found, and the limits
Who: The nature dose evidence used here Measured: Whether nature contact causes better health Finding: Cross-sectional dose association; randomised evidence for affect, less for physical health
Why this certainty: The designs available cannot separate nature contact from the health and income that enable it. (Informal editorial assessment, not a formal GRADE rating.)
Limits: Long-term randomised trials of nature exposure are impractical. Applies to: Setting expectations: mood and stress, not disease prevention.
Identifier carried over from the 2026-10-11 abstract-level verification batch; not re-queried in this run. Source record
Where studies disagree
Does nature improve physical health?: The cross-sectional survey associates 120 or more minutes a week with better self-reported health (OR 1.59), while the meta-analysis of randomised trials found effects on positive and negative affect with less evidence for physical health benefits. The observational association is broader than the trial evidence, so the two should not be merged into one claim. (src-01, src-03)
Sources for this entry
Every identifier below was verified against PubMed on 2026-10-11 in an earlier batch. This run carried the identifiers over rather than re-querying them, and no retraction database was checked. Verification was at abstract level; full text was not read.
White 2019 White MP, Alcock I, Grellier J, et al. Spending at least 120 minutes a week in nature is associated with good health and wellbeing. Sci Rep. 2019;9(1):7730. doi:10.1038/s41598-019-44097-3. PMID: 31197192. PMID 31197192 · observational study · confidence weight 0.5 · abstract level
Compared with no nature contact, people reporting at least 120 minutes in the past week were more likely to report good health (OR 1.59 for 120-179 min) and high well-being (OR 1.23). Associations peaked at 200 to 300 minutes a week, and it didn't matter whether time came in one visit or several.
Hunter 2019 Hunter MR, Gillespie BW, Chen SY. Urban Nature Experiences Reduce Stress in the Context of Daily Life Based on Salivary Biomarkers. Front Psychol. 2019;10:722. doi:10.3389/fpsyg.2019.00722. PMID: 31019479. PMID 31019479 · observational study · confidence weight 0.5 · abstract level
A nature experience lowered salivary cortisol by 21.3% per hour beyond its normal daily decline. The benefit per minute was greatest between 20 and 30 minutes, with smaller added gains after that.
Coventry 2021 Coventry PA, Brown JE, Pervin J, et al. Nature-based outdoor activities for mental and physical health: Systematic review and meta-analysis. SSM Popul Health. 2021;16:100934. doi:10.1016/j.ssmph.2021.100934. PMID: 34646931. PMID 34646931 · systematic review meta analysis · confidence weight 1.0 · abstract level
In RCTs, structured nature-based activities improved positive affect (0.95, 95% CI 0.59 to 1.31) and reduced negative affect (-0.52, 95% CI -0.77 to -0.26). There was less evidence for physical health benefits. The most effective programs ran 8 to 12 weeks with sessions of 20 to 90 minutes; gardening and green exercise were among the effective formats.
Bratman 2015 Bratman GN, Hamilton JP, Hahn KS, et al. Nature experience reduces rumination and subgenual prefrontal cortex activation. Proc Natl Acad Sci U S A. 2015;112(28):8567-72. doi:10.1073/pnas.1510459112. PMID: 26124129. PMID 26124129 · controlled experiment · confidence weight 0.5 · abstract level
The nature walk reduced self-reported rumination and activity in a brain region linked to rumination; the urban walk didn't.
Antonelli 2019 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(8):1117-1134. doi:10.1007/s00484-019-01717-x. PMID: 31001682. PMID 31001682 · systematic review meta analysis · confidence weight 1.0 · abstract level
Salivary cortisol was lower in forest groups than urban groups (after intervention MD -0.05 ug/dL, 95% CI -0.06 to -0.04), with high heterogeneity; nearly all studies reported lower cortisol after forest exposure.