A new study has revealed that if you let it, your smart phone can tell if you are depressed.

The Northwestern Medicine tracked the GPS of 28 adults, finding that participants were more likely to be depressed if they spent too much time on their phones and too little time going out.

Of the 28 who participated, 14 were chosen for displaying medium to severe signs of depression and 14 for showing no signs of depression.

The study was 87 per cent accurate in detecting depression. Photo: AAP

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By tracking their movements and phone usage, the authors of the study predicted whether each of the participants was depressed and then checked their results.

The study found a direct correlation between the amount of time spent on smart phones and depression.

The average daily usage for depressed individuals was about 68 minutes, while for non-depressed individuals it was about 17 minutes.

A lack of regular habits was also linked to depression, with people who worked unpredictable hours or those who leave their house at a different time every day more likely to suffer depression.

“The significance of this is we can detect if a person has depressive symptoms and the severity of those symptoms without asking them any questions,” senior author David Mohr told Northwestern University.

“We now have an objective measure of behaviour related to depression. And we’re detecting it passively. Phones can provide data unobtrusively and with no effort on the part of the user.”

Researchers also found that tracking people’s movements and phone usage was more effective than simply asking them to rate their mood everyday.

The result of the study is something we already know: that when we’re depressed, we may feel more comfortable retreating to a world of screens than communicating with people who want to help us.

The study could lead to a preemptive monitoring of those at higher risk of depression, and to faster intervention.