For the first time, researchers say they've proven the longer you spend on social media, ironically the lonelier you feel.
Researchers at the University of Pennsylvania got 143 participants to fill out a survey on their mood and wellbeing, then over the next three weeks tracked their use of Facebook, Snapchat and Instagram.
Some were told to continue to use the popular apps as they had been, and others had to cut down to 10 minutes a day.
Three weeks later, the results were unambiguous.
"Here's the bottom line," says research leader Melissa Hunt.
"Using less social media than you normally would leads to significant decreases in both depression and loneliness. These effects are particularly pronounced for folks who were more depressed when they came into the study."
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Previous studies had found a link between social media use and mental health problems, but no causal link had been found until now, said Dr Hunt.
"We set out to do a much more comprehensive, rigorous study that was also more ecologically valid."
She said it's a "little ironic" that using social media appears to increase feelings of loneliness, but it makes sense.
"Some of the existing literature on social media suggests there's an enormous amount of social comparison that happens. When you look at other people's lives, particularly on Instagram, it's easy to conclude that everyone else's life is cooler or better than yours."
She said it's not clear whether other social media sites such as Twitter have the same effect on their users, but wouldn't be surprised.
"When you're not busy getting sucked into clickbait social media, you're actually spending more time on things that are more likely to make you feel better about your life... In general, I would say, put your phone down and be with the people in your life."
The study's findings were published in the Journal of Social and Clinical Psychology.