“Get outside more” is common advice, but the research behind it is more specific and more measurable than the generic framing suggests.
The Japanese forest bathing studies
Research on shinrin-yoku, or “forest bathing,” conducted extensively in Japan, has found measurable reductions in cortisol, blood pressure, and heart rate after time spent in forested environments compared to urban settings, along with increased activity of natural killer cells — part of the immune system’s response to infected or cancerous cells.
How much time is actually needed
A widely cited 2019 study in Scientific Reports found that people who spent at least 120 minutes in nature per week — whether in one visit or split across several — reported significantly higher levels of health and wellbeing than those who spent no time in nature, with no additional benefit found beyond that threshold in the study’s sample.
Why it works
Leading theories include attention restoration — natural environments require less directed cognitive effort than urban environments packed with signage, traffic, and decisions — and reduced exposure to noise and ambient stressors common in built environments.
It doesn’t have to be a forest
Urban parks and green spaces show similar, if somewhat smaller, benefits compared to deep wilderness, meaning the effect is accessible without significant travel for most people.
The bottom line
Two hours a week in nature, park or forest, is a modest, well-supported target with measurable physiological benefits — a realistic goal rather than an aspirational one.
