A walk in the forest may do more than just feel relaxing. In a study by neuroscientists at the Max Planck Institute for Human Development, researchers compared the effects of a one-hour walk in a forest with a walk along a busy city shopping street. Using MRI scans before and after the walks, they measured how participants' brains responded to stress. The results showed that a forest walk reduced stress-related brain activity by around 50%, providing direct evidence of nature’s calming effect. Surprisingly, the city walk did not increase participants’ stress levels. Follow-up experiments suggest that the combination of forest sights, sounds and smells delivers the strongest boost to well-being, while even brief exposure to greenery can have positive effects on the brain.