A new study showed that smartphones can be used to detect someone's depression. People who are suffering from depression spend three times longer on their smartphones compared to happy individuals. Researchers at Northwestern University looked at the phone sensor data of 28 people for two weeks. They monitored the phone usage and GPS locations of the participants. The GPS locations were also tracked every five minutes.

The participants also agreed to complete survey questionnaires designed to measure their depression levels and symptoms such as sadness, loss of pleasure, hopelessness, sleep problems, changes in appetite and difficulty concentrating.

The analysis showed that half of the participants did not show signs of depression while the other half had mild to severe depression. Depressed people tend to stay in some areas and spend 68 minutes on their smartphones compared to the non-depressed individuals who were moving to different places and were using their devices for 17 minutes. Though the depressed people stay online longer, much of the time are spent playing video games or surfing the net instead of chatting with other people.

"The data showing depressed people tended not to go many places reflects the loss of motivation seen in depression," David Mohr, senior study author and a clinical psychologist and professor of preventive medicine at Feinberg, said in a university news release. "When people are depressed, they tend to withdraw and don't have the motivation or energy to go out and do things."

"People are likely, when on their phones, to avoid thinking about things that are troubling, painful feelings or difficult relationships," Mohr said. "It's an avoidance behavior we see in depression."

The findings of the study can be beneficial in the improvement of monitoring people who are at risk of depression so that heath care providers can help immediately. The researchers plan to continue their study to see if encouraging people to go to different places can reduce their depression symptoms.

The study was published in the July 15 issue of the Journal of Medical Internet Research.