Between the years of 2012 and 2015, something unexpected occurred. The rates of depression, suicide attempts and suicide among teens increased substantially. Thanks to new research, published in Clinical Psychology Science, the culprit has been identified.

The research was led by Professor Jean Twenge of San Diego University, along with her colleagues. In an article published by The Conversationalist, Twenge wrote that regardless of background (less privilege versus high privilege), teens born after the year of 1995 were more likely to experience mental health issues than their millennial predecessors.

While determining the cause, the researchers ruled out several factors. Because there was a period of steady economic growth and falling unemployment, the researchers didn’t believe economic malaise was to blame.

And because income inequality is nothing new (the gap between the poor and the rich has been widening for decades, after all), this factor was ignored. Finally, the amount of time teenagers spent on homework in this five-year period did not change at all, ruling out academic pressure.

The one thing that did change was the amount of time teenagers spent on smartphones. According to the Pew Research Center, smartphone ownership passed the 50 percent threshold in late 2012. That’s about the same time teen depression and suicide skyrocketed. Five years later, 73 percent of teens had access to a smartphone.

The researchers concluded that smartphone use and depression increase in tandem. The teenagers who spent five or more hours a day online were 71 percent more likely to have at least one suicide risk factor (depression, contemplating suicide, making a suicide plan, or attempting suicide), than teens who spent less than an hour a day online.

“Overall, suicide risk factors rose significantly after two or more hours a day of time online,” wrote Twenge.

The psychology Professor and her colleagues hypothesize that time spent online can adversely affect mental health in indirect ways. For instance, when teens spend more time online, they spend less time with their friends.

“Interacting with people face to face is one of the deepest wellsprings of human happiness; without it, our moods start to suffer and depression often follows. Feeling socially isolated is also one of the major risk factors for suicide,” wrote Twenge.

The author added that teens who spent more time online and less time being social with friends were more likely to be depressed. And, that’s exactly what has taken place since 2012.

The researchers also theorize that the use of smartphones is causing teenagers to sleep less. Wrote Twenge, “Not sleeping enough is a major risk factor for depression, so if smartphones are causing less sleep, that alone could explain why depression and suicide increased so suddenly.”

Though depression and suicide have many causes, not limited to genetic predisposition, family environments, and bullying and trauma, the correlation between the use of smartphones and the rising prevalence of depression, suicide attempts, and suicide should not be ignored.

Teens may be slipping into depression as a result of too much screen time, not enough face-to-face social interaction, inadequate sleep, or a combination of all three. For future generations to thrive, all factors need to be addressed.

As Twenge concluded, “It’s not too early to think about limiting screen time; let’s hope it’s not too late.”

Sources: ConsciousLifeNews.com; TheConversation.com