Does spending time in nature actually reduce stress?

Time in nature produces measurable short-term changes in the body, including a lower heart rate, lower systolic blood pressure and greater parasympathetic nervous system activity (Park et al., 2010; Andrade et al., 2026). Self-reported tension, anxiety, fatigue and low mood drop consistently across studies. Evidence for longer-term change is thin and the quality of existing studies is rated low, so the honest claim is a real short-term effect rather than a cure.

What is the difference between the sympathetic and parasympathetic nervous system?

The sympathetic branch of the autonomic nervous system prepares the body for action by raising heart rate and breathing, sending blood to the muscles and pausing digestion. The parasympathetic branch does the opposite, slowing the heart, lowering blood pressure and restoring digestion, which is why it is called the rest-and-digest system. Both branches run continuously, and research in forest environments shows the balance shifting toward the parasympathetic side.

How long do you need to be in nature to feel calmer?

Twenty to thirty minutes gives the largest benefit per minute spent, according to a study that tracked salivary cortisol in 36 city dwellers taking short nature breaks over eight weeks (Hunter, Gillespie and Chen, 2019). A meta-analysis of blood pressure studies similarly found that sessions of twenty minutes or longer outperform shorter ones (Qiu et al., 2022). Benefits continue past thirty minutes at a slower rate, which is one reason a guided forest therapy session runs two to three hours.

Does forest bathing lower cortisol?

The evidence on cortisol is mixed and weaker than most articles suggest. Park et al. (2010) recorded lower salivary cortisol after forest visits than after city visits, and Hunter et al. (2019) found a drop beyond the normal daily decline. A 2026 meta-analysis pooling eleven studies found no clinically meaningful cortisol change, with very high variation between studies (Andrade et al., 2026). Cortisol also falls naturally through the morning, so the hour of measurement alone can produce an apparent effect.

Can forest therapy replace treatment for anxiety or burnout?

Forest therapy does not replace medical or psychological care, and a guide is not a therapist. A session may support relaxation and wellbeing, and participants often say they feel less tense and think more clearly afterwards, but it involves no assessment, diagnosis or clinical treatment. Anyone dealing with persistent anxiety, low mood or exhaustion should speak to a doctor or psychologist, and can use time in nature alongside that care rather than instead of it.

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Nature and the Nervous System: What Calms Down in a Forest

14 September 2026

Time in a forest shifts the autonomic nervous system toward its parasympathetic branch, the side that slows the heart, lowers blood pressure and lets digestion resume. Field experiments across 24 Japanese forests with 280 participants recorded lower salivary cortisol, lower pulse rate, lower blood pressure, greater parasympathetic activity and lower sympathetic activity after a forest visit than after a matched visit to a city (Park et al., 2010). The walking in that study lasted about sixteen minutes.

Those are the headline numbers, and an honest version carries their limits in the same breath. A 2026 systematic review and meta-analysis of eleven forest bathing studies found consistent reductions in tension and anxiety, depression, anger, fatigue and confusion, a mean drop in heart rate of four beats per minute, and lower systolic blood pressure. The same analysis found no clinically meaningful change in salivary cortisol, no clear effect on diastolic blood pressure, and rated the quality of evidence across every outcome as very low, largely because ten of the eleven studies compared people before and after rather than against a control group (Andrade et al., 2026).

I guide forest therapy in Slovenia and have facilitated people in nature since 2019, so I watch the gap between what people feel and what instruments catch at every session. Participants say almost the same sentence in the closing circle: their shoulders dropped, and they cannot say when. Research confirms that shift better than it explains it. This article covers what moves, what does not, how much time it takes, and how a guided session uses that time. For the wider evidence picture I keep a separate summary of what the research says about forest therapy.

The two settings your body runs on

The autonomic nervous system runs the functions you never consciously control, and it has two branches that balance each other. The sympathetic branch prepares you to act: heart rate rises, breathing quickens, blood moves to the muscles, digestion pauses. The parasympathetic branch does the recovery work, slowing the heart, lowering blood pressure and restoring digestion, which is why physiologists call it the rest-and-digest system. The vagus nerve carries much of that parasympathetic traffic between the brain and the heart, lungs and gut.

A sympathetic response is not a malfunction. You want it when a car pulls out in front of you. The difficulty for most people I meet is not that the alarm works, it is that nothing in a normal working day tells it to stop: notifications, open-plan noise, a calendar with no gaps in it. Forests are unusually good at delivering that signal, because they offer a stream of sensory information that asks nothing of you.

What measurably changes

Heart rate, blood pressure and self-reported mood are the measurements that move most reliably in forest research. The 24-forest study found greater parasympathetic and lower sympathetic activity in the forest condition, measured through heart rate variability. The 2026 meta-analysis put the average heart rate reduction at four beats per minute, with systolic blood pressure lower and diastolic unchanged. A separate meta-analysis of 21 blood pressure studies covering 2,270 participants found that sessions of twenty minutes or longer outperformed shorter ones, and that older participants and those with higher starting blood pressure benefited most (Qiu et al., 2022).

Mood is the most consistent finding in the whole field. A meta-analysis restricted to randomised controlled trials found a significant reduction in depression scores, while the pooled blood pressure effect did not reach significance (Yi, Seo and An, 2022). Two meta-analyses disagreeing about blood pressure while agreeing about mood tells you where the ground is firm and where it is soft.

Where the evidence is thinner than the headlines

Cortisol is the weakest link in the popular story about nature and stress. Salivary cortisol became the signature measurement of forest bathing research because Park and colleagues used it in 2010, and a great deal of marketing has been built on it since. The 2026 meta-analysis found no clinically meaningful cortisol change across the pooled studies, with variation between studies so extreme that they barely agree with one another. Cortisol also follows a steep daily curve that falls through the morning on its own, so a study that fails to account for the hour of the measurement will record a drop the forest did not cause.

Three further limits are worth carrying. Most published studies use small samples, often a few dozen people. Most were run in Japan, South Korea and China, with participants who may bring different expectations to a forest than a Slovenian or a British visitor does. And almost nobody has followed participants for a year: a 2026 meta-analysis of 25 controlled studies reports that virtually all of them measured people immediately after the session and never again, which is also the strongest practical argument for going regularly rather than once (Pan et al., 2026). How often should you go to the forest takes that question on directly. Research suggests a real short-term effect on the nervous system. Research has not established a long-term one, and a page that tells you otherwise is selling something.

Attention gets tired too

Stress is only half of the picture, because directed attention fatigues separately. Attention restoration theory describes the concentration you use to stay on a task and block out distractions as a limited resource that wears down through a working day. Restoring it needs four conditions: being away from the usual demands, soft fascination that holds attention without effort, enough extent that the setting feels like a world of its own, and compatibility between the place and what you want to do there (Kaplan, 1995). Moving water, wind in a canopy and light through leaves supply soft fascination without asking you to decide anything.

Recovery can begin faster than most people expect. In a study of 120 people who watched a stress-inducing film and were then shown video of natural or urban settings, recovery measured through heart period, muscle tension, skin conductance and pulse transit time was faster and more complete after the natural scenes (Ulrich et al., 1991). Notice what that study actually used: videotape, not a forest. The finding suggests the effect begins in perception, and it also means nobody should stretch it into a claim about real woodland.

How much time it takes

Twenty to thirty minutes is where time in nature pays back most per minute spent. Researchers gave 36 city dwellers one instruction for eight weeks: spend at least ten minutes in a natural setting, at least three times a week, choosing the place and the hour yourself. Salivary cortisol fell 21.3 percent per hour beyond its normal daily decline, and the efficiency of that drop per minute spent peaked between twenty and thirty minutes, after which benefits kept accumulating at a slower rate (Hunter, Gillespie and Chen, 2019). The blood pressure meta-analysis points the same way, with sessions above twenty minutes outperforming shorter ones.

Twenty minutes is a floor worth defending on an ordinary Tuesday, not a target. A guided forest therapy session runs two to three hours for a different reason: that length is what lets a group move from arriving, through a sequence of sensory invitations, to a closing that does not feel abrupt. On how often to repeat it, the honest answer is that a regular short habit beats a rare long one, and the studies that shifted clinical measures used repeated sessions rather than one memorable outing. The burnout article works through that evidence in detail.

What a guided session does with the time

A guided session takes the decisions away from you, and most of the effect lives there. On my sessions nobody chooses the route, the pace or the moment to turn back, and there is no place we have to reach. We begin standing still with a body scan and a slow opening of the senses, which takes twenty to thirty minutes on its own, then move into an invitation I use almost every time: noticing what is in motion. People walk more slowly than they believed possible and still find that ten metres of ground holds more than they expected.

Each invitation is followed by a circle where people say what they noticed, with no requirement to say anything. A sit spot in the middle of the session gives twenty minutes of permission to do nothing, and participants often name it afterwards as the part they resisted first and then wanted more of. We close with a forest tea ceremony made from a plant growing nearby, the first cup poured for the forest. For the full set of invitations and why they take the shape they do, read about the povabila.

What the forest cannot do

Forest therapy may support relaxation and wellbeing, and it is not treatment for anxiety, depression, trauma or burnout. I am a guide, not a therapist, and that distinction is not modesty. A session holds open space and offers sensory invitations; it includes none of the assessment, diagnosis or clinical work a psychologist or doctor does. If something heavy surfaces during a session, my job is to keep the space safe and to point you toward the right professional afterwards. Anyone selling time in the forest as a treatment is claiming more than the evidence allows.

Where to start in Slovenia

Slovenia makes the twenty-minute floor easy to clear, because forests cover 58 percent of the country, third in the European Union behind Sweden and Finland (Zavod za gozdove Slovenije). In Ljubljana that means Rožnik or Golovec on a weekday morning rather than a planned expedition, and I have written a guide to the forests around Ljubljana for anyone who wants somewhere specific to begin. For a guided session, alone or with a group, see the sessions I run.

Start with the forest you can reach on foot. Your nervous system does not check whether the woodland is famous. It probably does not check the chemistry of the air either, although that question has its own body of research, which I go through in phytoncides: what forest air actually does.

Common questions

Does spending time in nature actually reduce stress?: Time in nature produces measurable short-term changes in the body, including a lower heart rate, lower systolic blood pressure and greater parasympathetic nervous system activity (Park et al., 2010; Andrade et al., 2026). Self-reported tension, anxiety, fatigue and low mood drop consistently across studies. Evidence for longer-term change is thin and the quality of existing studies is rated low, so the honest claim is a real short-term effect rather than a cure.
What is the difference between the sympathetic and parasympathetic nervous system?: The sympathetic branch of the autonomic nervous system prepares the body for action by raising heart rate and breathing, sending blood to the muscles and pausing digestion. The parasympathetic branch does the opposite, slowing the heart, lowering blood pressure and restoring digestion, which is why it is called the rest-and-digest system. Both branches run continuously, and research in forest environments shows the balance shifting toward the parasympathetic side.
How long do you need to be in nature to feel calmer?: Twenty to thirty minutes gives the largest benefit per minute spent, according to a study that tracked salivary cortisol in 36 city dwellers taking short nature breaks over eight weeks (Hunter, Gillespie and Chen, 2019). A meta-analysis of blood pressure studies similarly found that sessions of twenty minutes or longer outperform shorter ones (Qiu et al., 2022). Benefits continue past thirty minutes at a slower rate, which is one reason a guided forest therapy session runs two to three hours.
Does forest bathing lower cortisol?: The evidence on cortisol is mixed and weaker than most articles suggest. Park et al. (2010) recorded lower salivary cortisol after forest visits than after city visits, and Hunter et al. (2019) found a drop beyond the normal daily decline. A 2026 meta-analysis pooling eleven studies found no clinically meaningful cortisol change, with very high variation between studies (Andrade et al., 2026). Cortisol also falls naturally through the morning, so the hour of measurement alone can produce an apparent effect.
Can forest therapy replace treatment for anxiety or burnout?: Forest therapy does not replace medical or psychological care, and a guide is not a therapist. A session may support relaxation and wellbeing, and participants often say they feel less tense and think more clearly afterwards, but it involves no assessment, diagnosis or clinical treatment. Anyone dealing with persistent anxiety, low mood or exhaustion should speak to a doctor or psychologist, and can use time in nature alongside that care rather than instead of it.