Robin Mejia reports on a review paper Green exercise may be good for your head in Environmental Science and Technology by Jules Pretty and Jo Barton (DOI 10.1021/es903183r). They did a a meta-analysis of 10 studies and found that outside activity for as little as five minutes included mood and self-esteem.
… the group has studied the effects of different types of green exercise on a variety of populations, from gardening by visitors to university farms to walking and sailing activities for young offender groups, as well as walking by members of urban flower shows. This new analysis reviewed 10 of these studies, which involved a total of 1252 participants. In each study, mood and self-esteem were measured using two widely accepted scales. All types of green exercise led to improvements in the mental health indicators. Most surprising to the researchers was that the strongest response was seen almost immediately.“You get a very substantial benefit from the first five minutes. We should be encouraging people in busy and stressed environments to get outside regularly, even for short bits of time,” says Pretty. After that, increased green exercise continues to add benefit, but with decreasing returns. However, a full day of activity causes another spike in the level of benefit. Both healthy people and those with mental health disorders benefited, with the mentally ill showing the strongest improvement in self-esteem.
Frances Kuo, the director of the Landscape and Human Health Laboratory at the University of Illinois at Urbana-Champaign, notes that the new analysis looked at 10 studies with over 1000 participants, which raises the confidence that they’re seeing a valid pattern. Yet the studies were not randomized trials. “None of the studies involved taking people and assigning them to different ‘doses’ of nature; rather, they looked at how people who sought out nature on their own responded to nature.”
Still, the analysis may help those arguing that the built world should be designed to facilitate things such as walking near trees, not driving from garage to parking lot. “Planners and consultants can put this in front of policy makers and say this is serious research that’s been published in the scientific literature,” says Sullivan.