Many people spend their workdays indoors under fluorescent lights and in front of computers, then return home to bask in the glow of television screens.

But spending too much time inside isn't good for us. And nature is beneficial - maybe essential - for human health. Psychologists and health researchers are finding more and more science-backed reasons we should spend time outside.

In her recent book, The Nature Fix: Why Nature Makes Us Happier, Healthier, and More Creative, journalist Florence Williams writes that she started investigating the health benefits of nature after moving from the mountainous terrain of Boulder, Colorado, to what she describes as "the anti-Arcadia that is the nation's capital" - Washington, DC.

"I felt disoriented, overwhelmed, depressed," she writes. "My mind had trouble focusing. I couldn't finish thoughts. I couldn't make decisions and I wasn't keen to get out of bed."

We don't all need to live in a place as stunning as Boulder - and most of us can't get live anywhere too remote for smartphones or internet access.

But we do need to spend time in natural environments. That could be beautiful hiking trails or even just a nice park. Here's why it's so important to do so.

It could improve your short term memory

Several studies show that nature walks have memory-promoting effects that other walks don't.

In one study, University of Michigan students were given a brief memory test, then divided into two groups. One group took a walk around an arboretum, and the other took a walk down a city street.

When the participants returned and did the test again, those who had walked among trees did almost 20 percent better than the first time. The ones who had taken in city sights instead did not consistently improve.

A similar study on depressed individuals found that walks in nature boosted working memory much more than walks in urban environments.

It has a de-stressing effect

Something about being outdoors changes the physical expression of stress in the body.

One study found that students sent into the forest for two nights had lower levels of cortisol - a hormone often used as a marker for stress - than those who spent that time in the city.

In another study, researchers found a decrease in both heart rate and levels of cortisol in subjects in the forest when compared to those in the city. 'Stressful states can be relieved by forest therapy,' they concluded.

Among office workers, even the view of nature out a window is associated with lower stress and higher job satisfaction.

Spending time outside reduces inflammation

When inflammation goes into overdrive, it's associated in varying degrees with a wide range of ills including autoimmune disorders, inflammatory bowel disease, depression, and cancer. Spending time in nature may be one way to help keep it in check.

In one study, students who spent time in the forest had lower levels of inflammation than those who spent time in the city. In another, elderly patients who had been sent on a weeklong trip into the forest showed reduced signs of inflammation as well as some indications that the woodsy jaunt had a positive effect on their hypertension.

The outdoors helps eliminate fatigue

You know that feeling where your brain seems to be sputtering to a halt? Researchers call that 'mental fatigue.'

One thing that can help get your mind back into gear is exposing it to restorative environments, which, research has found, generally means the great outdoors. One study found that people's mental energy bounced back even when they just looked at pictures of nature. (Pictures of city scenes had no such effect.)

Studies have also found that natural beauty can elicit feelings of awe, which is one of the surest ways to experience a mental boost.

Outdoor experiences may help fight depression and anxiety

Anxiety, depression, and other mental health issues may all be eased by some time in the great outdoors - especially when that's combined with exercise.

One study found that walks in the forest were associated with decreased levels of anxiety and bad moods, and another found that outdoor walks could be 'useful clinically as a supplement to existing treatments' for major depressive disorder.

'Every green environment improved both self-esteem and mood,' found an analysis of 10 earlier studies about so-called 'green exercise,' and 'the mentally ill had one of the greatest self-esteem improvements.' The presence of water made the positive effects even stronger.

Being outside may protect your vision

At least in children, a fairly large body of research has found that outdoor activity may have a protective effect on the eyes, reducing the risk of developing nearsightedness (myopia).

'Increasing time spent outdoors may be a simple strategy by which to reduce the risk of developing myopia and its progression in children and adolescents,' a 2012 review of the research concluded.

In Taiwan, researchers studied two nearby schools where myopia was equally common. They told one school to encourage outdoor activity during recess and monitored the other as a control. After one year, the rate of myopia in the control school was 17.65 percent; in the 'play outside' school, it was just 8.41 percent.

It could improve your ability to focus

We know the natural environment is 'restorative,' and one thing that a walk outside can restore is your waning attention.

In one study, researchers worked to deplete participants' ability to focus. Then some took a walk in nature, some took a walk through the city, and the rest just relaxed. When they returned, the nature group scored the best on a proofreading task.

The attentional effect of nature is so strong it might help kids with ADHD, who have been found to concentrate better after just 20 minutes in a park. "Doses of nature' might serve as a safe, inexpensive, widely accessible new tool … for managing ADHD symptoms,' researchers wrote.

You may perform better on creative tasks after being outside

'Imagine a therapy that had no known side effects, was readily available, and could improve your cognitive functioning at zero cost.' That's the dramatic opening to a 2008 paper describing the promise of so-called 'nature therapy' - or, as a non-academic might call it, 'time outside.'

Another study found that people immersed in nature for four days - significantly more time than a lunchtime walk in the park - boosted their performance on a creative problem-solving test by 50 percent.

Spending time outside lowers blood pressure

With all these other salutary effects, it's no surprise that outdoor time - which usually involves walking - lowers blood pressure too, as is shown by a number of studies.

One intensive study of 280 participants in Japan found that along with lowering stress hormone concentrations by more than 15 percent, a walk in the forest lowered average pulse by almost 4 percent and blood pressure by just over 2 percent.

Outdoor sessions may even help prevent cancer

Research on this connection is still in its earliest phases, but preliminary studies have suggested that spending time in nature - in forests, in particular - may stimulate the production of anti-cancer proteins.

The boosted levels of these proteins may last up to seven days after a relaxing trip into the woods.

Studies in Japan, where 'shinrin-yoku' or 'forest-bathing' is treated as preventative medicine, have also found that areas with greater forest coverage have lower mortality rates from a wide variety of cancers. While there are too many confounding factors to come to a concrete conclusion about what this might mean, it's a promising area for future research.

Forests also might boost your immune system

The cellular activity that is associated with a forest's possible anti-cancer effects is also indicative of a general boost to the immune system you rely on to fight off less serious ills, like colds, flus, and other infections.

A 2010 review of research related to this effect noted that 'all of these findings strongly suggest that forest environments have beneficial effects on human immune function,' but acknowledged that more research on the relationship is needed.

With all this, it's not too surprising that outdoor time is associated with a lower risk of early death

Nearby green space seems to be especially important for residents of urban environments, according to a Dutch study of 250,782 people, which found a strong positive connection between green space and health.

A follow-up study by the same research team found that a wide variety of diseases were less prevalent among people who lived in close proximity to green space. Other studies have made a direct link between time spent in forests and other measures of overall health.

A recent study in Environmental Health Perspectives found a similar connection, finding about a 12 percent lower mortality rate, with the biggest improvements related to reduced risk of death from cancer, lung disease, or kidney disease.

This article was originally published by Business Insider.

More from Business Insider: