Your Body Knows Before You Do

I hike a lot. In the Alps where I live that is not a decision but everyday life. When I walk for hours something happens to me. The body moves, nature calms the senses and at some point I stop thinking. I walk and look. The views, the impressions, the sound of a stream, the wind. It puts me in a state I need to completely switch off. Many hikers report the same thing.

Then I enter a mountain hut. The menu can be as good as it wants. If the atmosphere is wrong I am quickly back outside.

A room is a risk. It can work or it can repel. Nature rarely repels. A room can. Smell, noise, cold, tiled floors instead of wood, fluorescent light instead of daylight, the stench of grease from the kitchen. Usually it is the atmosphere. You look for warmth and find coldness. That is immediately off-putting.

When the naturalness continues inside it is different. Wood, warm light, a tiled stove, an open fireplace. The state remains. The transition from outside to inside is harmonious. But a cool room with hard contrasts, modern materials, black and white design language flips the state instantly.

In the ski resorts I see this more and more clearly. Where there used to be nostalgia there are now central phone charging stations. Modernity imported from the city. City people feel comfortable, everything works. Efficiency becomes more relevant with every building in the Alps. First it was mass processing with sausage on a tray, now it is modern design, open spaces, lots of light and even more efficiency. Slowing down, lingering, leisure, all of that is fading into the background.

I wondered whether this is just my sensitivity or whether science confirms what I feel.

Four to seven minutes

Roger Ulrich ran an experiment in 1991 that remains one of the most cited in environmental psychology (Ulrich et al., 1991, Journal of Environmental Psychology). 120 subjects watched a stress-inducing film about workplace accidents. Then either a nature video or a city video. What was measured was not what people said but what their bodies did. Four indicators simultaneously: heart rate, blood pressure, skin conductance, facial muscle tension.

Skin conductance responded fastest. Within the first three minutes the difference was significant. After four to seven minutes all four indicators had diverged. The nature group recovered faster and more completely. Heart rate slowed to its lowest level since the stress film. With the city videos it accelerated.

What was remarkable was not just the speed. Nature did not simply return subjects to their baseline. It pushed them beyond it. Mood after the nature video was more positive than before the stress film.

Forest or water, heavy or light traffic

Ulrich showed two different nature videos. One with forest, one with water. No significant difference. He also showed two city videos. One with heavy traffic, one with light. No significant difference.

That means it is not the intensity that decides. It is the category. Nature or not. The body does not distinguish between forest and lake. But it immediately distinguishes between nature and city. No matter how quiet the city is.

A state like meditation

In the paper Ulrich expressed a hypothesis he could not prove but that struck me. He wrote that nature may trigger a “meditation-like state with open eyes.” Parasympathetically dominated. Awake but deeply relaxed.

I know this state. Not from theory but from hiking. After hours in nature I am awake and at the same time so calm that any disturbance immediately stands out. Ulrich measured this in 1991. I have experienced it a hundred times since.

He found 36 correlations between positive feelings and body measurements. All in the expected direction. The better the mood the slower the heart, the lower the blood pressure, the less skin conductance. The body and mood speak the same language.

What happens when you enter the room

Twelve years after Ulrich, Terry Hartig moved the experiment into the field (Hartig et al., 2003, Journal of Environmental Psychology). 112 subjects. One group walked 50 minutes through a nature reserve, the other through a city. Before and after each group sat in a room. The nature group in a room with a view of trees. The city group in a windowless room.

Something happened already during the ten minutes of sitting. Diastolic blood pressure dropped significantly for those with the tree view. For those without a window it did not. Then the walk. After 30 minutes systolic blood pressure in the nature group was about 6 mmHg lower than in the city group. That corresponds to the effect of mild blood pressure medication.

But then something unexpected happened. When the subjects turned around and walked back toward the lab the values converged again. The body was not only responding to the environment. It was responding to the direction. Walking back meant the nature visit was ending. The body registered that before the subjects thought about it.

Two separate processes

Hartig found something else that is little known. Attention and blood pressure developed differently in the two environments. But they did not correlate with each other.

That means nature calms the body and sharpens attention but through two different pathways. And the attention improvement came less from nature improving attention than from the city degrading it.

When I enter a mountain hut after a long day of hiking both systems are active. My body is deeply relaxed. My attention is sharpened. I notice more. The cold floor, the wrong light, the smell. In the city I would ignore all of that because my attention would already be exhausted.

Science has no direct evidence for this. But Koivisto showed (Koivisto et al., 2022, Frontiers in Psychology) that people who grew up in nature find cities more aversive. More nature experience increases sensitivity to non-natural environments. It does not decrease it.

Anger in the city, calm in nature

In Hartig’s study anger decreased in nature and increased in the city. The authors highlighted this because anger is clinically relevant. It is linked to cardiovascular disease and to violence. A city that generates anger generates disease and conflict. A natural space that reduces anger generates health and calm.

The drive to the test site was itself a stressor. 40 minutes of driving raised systolic blood pressure by nearly 8 mmHg. That was not part of the experiment. That was the commute. Everyday life.

The data exists

Ulrich’s 1991 paper has over 3,000 citations. Hartig’s study is among the most cited field studies in environmental psychology. The data is not new and not controversial.

But mountain huts in ski resorts are built with tiled floors. Efficiency replaces comfort. Children sit in windowless classrooms, employees in air-conditioned open-plan offices, patients in hospitals without a view of trees.

Parents should ask themselves what rooms their children learn in. Employees should ask themselves why they are more exhausted after eight hours in an office than after eight hours outside. Business owners should calculate what productivity loss from bad rooms costs. Investors should calculate what sick days cost that better buildings could prevent.

Your body knows before you do. Four to seven minutes. The data exists and is being ignored.