Viewing trees helps people become less stressed - and the effect increases the more trees are visible.

A new study by researchers at University of Illinois has confirmed the long-held understanding that natural scenery can be a useful tool in helping reduce psychological stress.

The research team, led by Dr Bin Jiang, subjected 158 volunteers to mildly stressful scenarios, including preparing a speech and delivering it to a group of people, after which they were asked to perform a subtraction task in front of judges and a video camera.

After undertaking the stress-inducing activities, the volunteers used a VR headset to view one of a selection of six-minute 360-degree videos featuring urban areas with variable amounts of visible tree canopy coverage.

The participants’ levels of stress were measured by self-reported questionnaire – and the results revealed a positive, linear association between the density of trees and recovery from stress recovery

“These findings suggest that viewing tree canopy in communities can significantly aid stress recovery and that every tree matters,” researchers said.

The study is only the latest in a body of research that has demonstrated the positive psychological benefits of spending time in natural environments.