Benefits to physical and mental health – evidence summary
There are now many reviews and summaries that provide overviews of research on specific aspects of the relationship between physical and mental health:
- The robust evidence base showing that exercise in the natural environment has many therapeutic benefits, for both mental and physical health, is summarised in the Natural England briefing : Links between natural environment and mental health evidence briefing (July 2016).
- A review of nature-based interventions for mental health care (Feb 2016), also by Natural England,  shows that taking part in nature-based activities helps people who are suffering from mental ill-health and can contribute to a reduction in levels of anxiety, stress and depression.
- A lot of the medical literature on the relationship between nature and wellbeing looks at psychological health in particular. Dan Bloomfield’s evidence report for NHS Forest, A Dose of Nature: Addressing chronic health conditions by using the environment (2014), is a useful resource.
There is a wealth of published research, much of which is referenced in the above overviews. Hartig et al. (2003) have demonstrated that nature can have a ‘restorative and therapeutic effect on the mind’. Pretty et al. (2005) found that taking part in green exercise led to improved self-esteem and a reduction in feelings such as depression and anger.
Reports in 2004 and 2007 by William Bird found that benefits from contact with the natural environment included reductions in obesity, heart disease, diabetes, cancer, stress, ADHD, aggression and criminal activities, among others.
In 2013, the Green Exercise Research Team at the University of Essex published a report evaluating the charity Mind’s ecotherapy programme (Bragg et al. 2013). It presents three mechanisms for how green space may confer healing effects: a possibly innate “dependence on, and desire to connect with, nature”; , the importance of nature in restoring attention; and the value of nature in reducing stress, which by default brings other benefits to individuals. This report also discusses the importance of interacting with green space through physical exercise and its benefits to mental wellbeing.
Green Exercise has been well-researched and proven to be a great way in which to improve fitness and enhance mental health and confidence. Studies demonstrate numerous correlations between exposure to nature and different indices of health and wellbeing, and an overview by Hartig et al. (2014) shows that the evidence regarding these benefits is strong.
Good evidence for Green Prescriptions, whereby a healthcare practitioner prescribes an activity in green space, comes from research done on a programme run by the New Zealand Ministry of Health. , That study, published in the British Medical Journal, found that a Green Prescription increases physical activity levels and improves quality of life over 12 months, without evidence of adverse effects. It also reported that for every ten Green Prescriptions written, one person achieved and sustained 150 minutes of moderate or vigorous leisure activity (using up an additional 1000 kcal) per week, and a 20–30 percent risk reduction in all-cause mortality (Elley et al. 2003). Such prescriptions were also shown, via a randomised control trial, to be cost effective at three different quality-adjusted life year thresholds, for adults who were previously inactive (Leung et al. 2012).
There is epidemiological evidence that is strong enough to support calls for nature-assisted therapies to be part of care. Significant improvements were found for varied outcomes in diverse diagnoses including schizophrenia (Maller et al. 2006). To be effective this means bringing together health and environmental management sectors (Annerstedt and Währborg 2011).
Greenspace also has proven therapeutic value within healthcare environments, facilitating good recovery and improved physical and mental health (for example Marcus 2005).
In 2005, some interesting research was carried out by the Mental Health Foundation (Halliwell)) which tried to understand why GPs do not refer patients to exercise for treatment of mild to moderate depression. It found that 42% of GPs would try exercise as one of their top three strategies if they themselves became depressed, but only 5% prescribe exercise to their patients.
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