The great outdoors: it's the place to head for when you're in need of peace and quiet, open spaces, beautiful scenery and exercise. Whether a huge mountain range or a local country park, these natural areas are a perfect tonic for our stressed-out lives, and their therapeutic effect is being used more and more to treat mental health.

As an example, in the foothills of the Snowdonia National Park in the UK, specialist therapy sessions are held to help people who suffer from depression, anxiety and stress. Outdoor art-related activities are held for patients, but the setting alone has been credited with improving the mood of patients. Art psychotherapist Pamela Stanley told the BBC that there was a "growing body of evidence" to support eco-therapy.

It's true that for most of us connecting with the natural world definitely lifts our spirits. But the mental health charity Mind says eco-therapy has been recognised as a formal type of treatment that can sometimes be prescribed to someone by a doctor. It doesn't involve taking medication, but instead it just develops a person's relationship with nature. This natural remedy can take on many forms, but can include doing yoga in a forest, gardening or even hugging a tree.

Evidence has shown there are many benefits of this 'green' therapy, including improving social contact, social and work skills and coping abilities. It's what Dr Rachel Bragg from the University of Essex calls 'psychological restoration'. She told the BBC's All in the Mind programme that nature-based therapies should be part of a "toolkit" of care for patients.

One reason why getting back to nature is, well, natural, is something called biophilia, a sort of understanding or empathy with the natural world. According to environmental psychologist Birgitta Gatersleben, "the idea that nature reminds us of life, and if we (are) exposed to the natural elements, then our sort of negative feelings get almost immediately replaced with positive emotions."

Of course, eco-therapy won't cure everything, but it is an option for therapists to use. And as we become more aware of the causes and effects of mental health, it's good to know that help might lie outside our towns and cities, and that nature can give us a helping hand.