A generic picture of a woman working in an office sitting at her desk typing on a computer.
A generic picture of a woman working in an office sitting at her desk typing on a computer. Reuters/Catherine Benson

Increased time spent with a mobile phone, computer or tablet could be linked to an uptick in symptoms of depression and suicidal thoughts among teenagers, according to a new study published on Tuesday. Researchers have found that increased screen-time particularly affects teenage girls.

Survey data on over 500,000 American teens and suicide statistics from the Centers for Disease Control and Prevention were analysed for the study by San Diego State University professor of psychology Jean Twenge. It was published in the journal Clinical Psychological Science.

Twenge, along with SDSU graduate student Gabrielle Martin and colleagues Thomas Joiner and Megan Rogers, found that the suicide rate for teen girls aged 13 to 18 rose by 65 percent between 2010 and 2015. Suicide-related thoughts among teenage girls increased by 12 percent. More female teens were reporting symptoms of severe depression, up by 58 percent.

Through the survey data, researchers looked to see if there was a link between the amount of screen-time and mental health symptoms. They learned that 48 percent of teens who spent five or more hours in front of device screens every day reported at least one suicide-related outcome.

The number is comparable to 28 percent of those who spent less than an hour a day on electronic devices. Depressive symptoms were also more common among teens who spent an increased amount of time in front of screens.

Economic struggles are generally thought to be associated with depression and suicide. But the US economy has been improving.

"Although we can't say for sure that the growing use of smartphones caused the increase in mental health issues, that was by far the biggest change in teens' lives between 2010 and 2015," Twenge said. She also warned that the increases in mental health issues among teenagers are “very alarming, adding teens who say they are struggling must be taken seriously.

Researchers also found that engaging in in-person social interaction instead of spending time on devices was linked to having fewer depressive symptoms and suicide-related outcomes. These in-person social interactions include engaging in sports and exercise and participating in religious activities.

Teens do not need to totally give up their screen-time to the lower risk of depression and suicide-related outcomes. According to Twenge, limiting screen-time to one or two hours per day would statistically fall into the safe zone for device usage. "But once you get to three hours and especially four and then, really, five hours and beyond, that's where there's much more significant risk of suicide attempts, thinking about suicide and major depression,” she added.