Got the blues? Head for some green spaces

Feeling down? Something as simple as a visit to your nearest park could perk you up with long-lasting positive effects on your mood, according to new research from the British Ecological Society and the University of Vermont.

For three months, a team from the University of Vermont studied hundreds of tweets every day and ran them through its sentiment analysis tool, Hedonometer. The tool rates words on their representative happiness, awarding each word it scrutinises a score. That enables it to estimate how happy Twitter users are at any given time.

In this case, it looked at how people were tweeting from 160 parks in San Francisco and concluded that people used more upbeat words when surrounded by trees and greenery.

Perhaps more surprisingly, they carried on tweeting happy thoughts for several hours after they’d left the park.

A new type of medicine

The latest study chimes with earlier research which shows that just two hours a week spent outside, surrounded by nature can be enough to improve your sense of wellbeing.

The physical and mental health benefits of connecting with nature is now being widely recognised. In Scotland, NHS Shetland has collaborated with wildlife charity the Royal Society for the Protection of Birds, on a programme of nature prescriptions. The suggestions include:

The soothing effects of the great outdoors are well documented. Harvard Medical School reports that time spent outside can reduce stress, anxiety, and depression: “The calming nature sounds and even outdoor silence can lower blood pressure and levels of the stress hormone cortisol, which calms the body's fight-or-flight response.”

That might go some way to explaining why people from the Nordic nations are some of the happiest in the world. Getting out and about in the great outdoors and spending time surrounded by nature is such an important part of Nordic life that it even has a name – friluftsliv, which translates as open-air living.

In addition, researchers from MIT have analysed possible links between air pollution and mood and found that “higher levels of pollution are associated with a decrease in people’s happiness levels.” They too fell back on social media activity, overlaying the sentiments of 210 million geotagged posts from Sina Weibo with daily air quality readings released by China’s Ministry of Environmental Protection.

“Pollution also has an emotional cost,” according to Xiaonan Zhang of Tsinghua University in Beijing. “People are unhappy, and that means they may make irrational decisions.”

When compared with the findings of the San Francisco study, the contrast could hardly be starker. “Across all the tweets, people are happier in parks. But the effect was stronger in large parks with extensive tree cover and vegetation,” explains research lead Aaron Schwartz.