Sitting Down for Too Long May Increase Anxiety
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People who spend too much time sitting down — be it during a daily commute, or in front of a computer or TV — may be at increased risk for anxiety, a new review finds.

Researchers looked at nine studies that assessed people's anxiety levels as well as their sedentary behavior, adding up how much time people spent doing activities like watching TV, working at a computer and playing video games. When examined together, the studies showed "moderate evidence" that increased sedentary behavior is associated with higher anxiety risk, the researchers wrote in the review, published online today (June 18) in the journal BMC Public Health.

Understanding the factors that may increase people's anxiety may help health care providers develop strategies that people could use to decrease and manage their anxiety, the researchers said. [11 Tips to Lower Stress]

"It is important that we understand the behavioral factors that may be linked to anxiety, in order to be able to develop evidence-based strategies in preventing [and] managing this illness," lead researcher Megan Teychenne, a lecturer at Deakin University's Centre for Physical Activity and Nutrition Research in Australia, said in a statement.

Studies have linked sedentary behavior with health problems, including increased risks of obesity, heart disease, type 2 diabetes and osteoporosis. But there is less research looking at how too much sitting might affect mental health, the researchers said.

Anxiety affects more than 27 million people worldwide, the researchers said. In the United States, 18.1 percent of people suffer from an anxiety disorder yearly, according to the National Institute of Mental Health.

In the review, the researchers looked at nine studies published between 1990 and 2014 that assessed both sedentary and anxiety levels. The studies varied in size, including anywhere from about 200 to more than 13,000 participants. Two of the studies looked at children and adolescents, and the other included surveys from adults.

The studies looked at people's risk of having a clinical anxiety disorder or having symptoms of anxiety. People with anxiety have excessive and persistent (but often unrealistic) worries that can get in the way of everyday life. Symptoms may include a pounding heart, difficulty breathing, an upset stomach, muscle tension, sweating and feeling faint or shaky, the researchers said.

"Anecdotally, we are seeing an increase in anxiety symptoms in our modern society, which seems to parallel the increase in sedentary behavior," Teychenne said. "Thus, we were interested to see whether these two factors were in fact linked."

Five of the nine studies found that increased sedentary behavior was linked with an increased risk of anxiety. However, the researchers found different results when they separated sitting time from screen time. Four of the studies showed that total sitting time was associated with increased anxiety risk. But the data linking people's risk of anxiety to how much time they spent looking at screens, such as TV and computer use, was not as strong, the researchers said.

However, the studies also showed that people's anxiety levels differed depending on the tasks they were doing when they were sitting. For example, a 2014 study showed that the amount of time spent sitting during a commute and overall sitting time were linked with increased anxiety risk, but that the amount of time spent sitting down for work or leisure activities had no link at all to anxiety. 

It's unclear how sedentary behavior might increase people's risk of anxiety, but the researchers floated several ideas. Sedentary behavior may cause disturbances in sleep patterns, poor metabolic health and even social withdrawal — when, for example, a person sits in front of a screen instead of interacting with people. All of these effects may cause anxiety risk to rise, the researchers said. [5 Things You Must Know About Sleep]

More work is needed to investigate the link between anxiety risk and sedentary behavior, the researchers said.

Follow Laura Geggel on Twitter @LauraGeggel. Follow Live Science @livescience, Facebook & Google+. Original article on Live Science.