Can we blame smartphones for our teen suicide epidemic?

We're currently going through something of an epidemic of teen suicides, and related symptoms. And the most likely reason might surprise you.
In the five short years between 2010 and 2015, the number of American teens who felt useless and joyless (classic symptoms of depression) spiked by 33%, teen suicide attempts increased by 23%, and teens between 13 and 18 years old who actually succeeded in committing suicide increased by 31%. This is affecting teens from every background, rich or poor, black or white, and in all geographical areas (this research is American, but I'm guessing that things are not dissimilar in any developed country).
So, what was causing such a drastic deterioration in teen mental health during a period of steady economic growth and falling unemployment? Income inequality continued to rise during the period, but no more so than before. Academic pressures piled up on kids, but again this was nothing new , and teens spent hardly any more time on homework than they did before.
The study authors pinpointed the most likely cause on the boom in teen smartphone ownership among teens during this period. In 2015, 73% of teens owned and used a smartphone, up from less than 50% just three years earlier. So, the spike in teen depression and suicide is closely mirrored by the use of smartphones.
This is not in itself evidence of a causal link, but further research shows that the length of time that teens spent online was linked to mental health issue: teens who spent five or more hours a day online (and there are more than you might think!) were 71% more likely to exhibit at least one suicide risk factor (depression, thinking about suicide, making a suicide plan, and attempting suicide). Now, being cautious, this does still not prove causality. But the evidence does not stop there. Two studies have shown that social media uses causes unhappiness, but that there is no causal link the other way around (i.e. unhappiness does not lead to increased social media use), and another study showed how giving up Facebook for just a week resulted in fewer feelings of depression.
Maybe all of this still does not amount to bullet-proof evidence of causality, but it is all part of a mounting body of evidence. And it kind of makes intuitive sense: for teens, more smartphones = more time on social media = less time interacting face-to-face with real friends and acquaintances (social isolation is a known major risk factor for suicide, and face-to-face social interaction is well proven to be a source of happiness and emotional wellbeing). Add to this another equation - more cellphone time = less sleep = more depression - and the picture starts to make a whole lot of sense, even if the research is not definitive.
Of course, what can be done about the problem, if problem it is, is another matter entirely. The smartphone genie is well and
truly out of the bottle (the cat is out of the bag, the can of worms is opened, etc, etc).