120 Minutes

There’s a number I can’t get out of my head.

120.

Minutes. Per week. In nature. It’s the threshold beyond which your brain begins to change in measurable ways. Not a sabbatical year. Not a mountain retreat. Not an exotic vacation. Two hours. Distributed across seven days. Among trees, water, open sky.

The data comes from a 2019 study published in Scientific Reports—a sample of nearly twenty thousand people in the United Kingdom. Those who reached 120 minutes weekly in natural environments reported significantly higher levels of wellbeing and perceived health compared to those who didn’t. The threshold was sharp. Like a step.

Below two hours, the effects were weak or absent. Above it, the benefit was robust, independent of age, income, health status, or ethnicity. And the most surprising part: how you distributed those two hours didn’t matter. One long walk on Saturday or twenty minutes daily—the result was equivalent.

The point isn’t “being outside is good for you.” We already knew that. We knew it before science confirmed it, knew it in our bodies before our minds could grasp it. The point is that there’s a dose. Like a drug. And almost nobody reaches it.

Data from Natural England shows that roughly 40 percent of British adults don’t spend even one hour per week in nature. In Italy, the numbers are similar, often worse—especially in urban areas where most of the population lives.

We spend on average over 22 hours a day indoors. Our brain—the same brain that evolved for millions of years in open spaces, under sunlight, surrounded by fractal patterns and non-linear sounds—now lives in a box with artificial light and backlit screens.

And we wonder why we’re exhausted.

The neuroscience behind these 120 minutes isn’t a mystery. It’s a well-documented mechanism involving at least three systems.

The first is the attentional system. Your brain has two modes of attention: one directed, voluntary, expensive—the one you use when you work, decide, solve problems. And one involuntary, that activates on its own when something captures you gently. Water flowing. Wind in the leaves. Light filtering through branches.

When you’re in a natural environment, the first rests. The second takes over. Neuroscientists call it soft fascination—and in that shift, your prefrontal cortex regenerates. It’s the Attention Restoration Theory, proposed by Kaplan in the 1980s and confirmed by hundreds of studies since.

The second system is stress. The amygdala—your brain’s alert center—reduces its activity in natural environments. Cortisol drops. Not slightly: studies show reductions up to 40 percent after sustained exposure to nature. Ulrich’s Stress Recovery Theory, parallel and complementary to Kaplan’s, has documented this effect since 1991.

The third is the default mode network—the neural circuitry that activates when you’re not doing anything specific. When your mind wanders. When you make unexpected connections. When you have an insight in the shower. This network functions differently in nature. A 2012 study by Atchley and colleagues showed a 50 percent increase in creative problem-solving ability after three days of immersion in nature. Not “I feel more creative”—measured, controlled, replicated.

Three systems. One threshold. 120 minutes.

And the question that drove me to build THALEA: why does almost nobody reach it?

Not from lack of willpower. From lack of structure. Of personalization. Of someone—or something—telling you: this park, this morning, for this specific reason tied to how your nervous system feels today.

I spent ten years studying the relationship between brain and nature. I wrote a book, a podcast listened to by two and a half million people, a TEDx talk. And in the end, the question was always the same: how do I make these 120 minutes accessible, personalized, and measurable?

The answer wasn’t another article. It was intelligence.

I’m not telling you to drop everything and move to the countryside. I’m telling you that your brain has a physiological need you’re probably not meeting, and that science has identified the minimum effective dose.

Two hours a week. Twenty minutes a day. In a park, along a river, under a tree.

Your brain already knows what to do with that time. It had a few million years to learn.

Everything else is noise.