I remember my parents saying that TV was going to rot my brain... then video games... before that it was comic books. Are there any reputable studies that show having a smart phone is detrimental to the health of a teenager? I've seen studies suggesting social media has a negative influence on the mental health of certain teens, but they aren't one and the same.

I think the difference is that there are fairly conclusive studies showing that social media use, for all ages, can negatively influences happiness. Studies for TV, comics, and games never seemed to be conclusive. They're all very different things. An understanding of one doesn't give an understanding of another. They each deserve their own conclusion. I suspect VR will be the next one in that list.

That's true, but are TVs and comics in your pocket or beside your bed 24/7 like phones? Are they computers that also directly attach you to several friends, family, acquaintances, and strangers instantaneously across several avenues? Do they notify you that you are "missing" something? I don't think there's any example in human history of things that have garnered the daily and sustained use of human attention more than smartphones, tablets, and the Internet.

There is the book The Shallows: What the Internet Is Doing to Our Brains by Nicholas Carr that covers this stuff and points to research.

There's also the Wall Street Journal article by him called Does the Internet Make You Dumber?.

https://www.wsj.com/articles/SB10001424052748704025304575284...