Spending too much time fiddling with your smartphone may be an indicator of depression, according to a new study published in the Journal of Medical Internet Research (a publication whose articles are, contrary to expectations, not all about the hazards of WebMD). Northwestern University and Michigan State University researchers found they could identify people with depression just by tracking their mobile phone usage, with an 87 percent accuracy rate. 

A group of 40 people recruited from Craigslist used an app that monitored their location and phone usage (based on how much time the phone’s screen was on) for two weeks. They also completed a questionnaire that evaluated them for symptoms of depression. At the end of the two-week period, the researchers found that phone usage and GPS data were better indicators of a subject’s depression than a daily survey that asked the participants to rate their sadness levels. 

Depressed subjects spent an average of 68 minutes per day on their phones, while non-depressed individuals spent 17 minutes per day using their phones on average. Depressed people (half the sample) also spent time in fewer locations, staying at home more.

There are many caveats that come along with these results. The study didn’t take into account whether the participants used their phones for work, and didn’t examine anyone under the age of 19 (both groups of heavy phone users). Nor did it monitor whether people were using the phones to talk to their friends and family or just playing Candy Crush. Plus, the sample was quite small. Due to insufficient data (like participants who forgot to charge their phones), only 20 women and eight men were included in the final sample. 

So just being on your phone a lot might not automatically mean you’re depressed. But it might be a warning sign, one that’s easier for psychologists to implement since an app is non-invasive and, for most people, always within reach.  

"People are likely, when on their phones, to avoid thinking about things that are troubling, painful feelings or difficult relationships," study co-author David Mohr of Northwestern explains in a press release. "It's an avoidance behavior we see in depression."