For the first time in the scientific literature, a 2010 paper showed dose-response relationships for the positive effects of nature on human mental health (Barton & Pretty, 2010). From a meta-analysis of 1252 people (of different ages, gender and mental health status) drawn from ten existing studies, it was shown that activity in the presence of nature (called “green exercise”) led to mental and physical health improvements. The activities analysed were walking, gardening, cycling, fishing, boating, horse-riding and farming.
The greatest health changes were observed in the young and the mentally-ill, though all age and social groups benefited. All natural environments were beneficial (including urban green); water though added something extra. A blue and green environment seems even better for health.
The largest positive effect on self-esteem came from a 5 minute dose.