GEOFF BENNETT: A number of states are moving to regulate social media use among children and teens.

New York state is the latest, with a new law that would allow parents to block their children from getting social media posts suggested by a platform's algorithm.

About one in five American adolescents report having anxiety and depression.

And CDC data show teenage girls are facing record levels of sadness and suicide risk.

It all comes amid a larger conversation about social media and smartphones.

Stephanie Sy has more.

STEPHANIE SY: On a recent morning in Durango, Colorado, students file into Mountain Middle School.

But before entering, 14-year-old Julia Fernandez shuts off her cell phone and puts it in her backpack.

So, this school has a ban on cell phone use.

How is that going?

JULIA FERNANDEZ, Student: I personally agree with the cell phone band.

We have a lot of people with anxiety and depression.

But I feel like it gives it a pause.

A day without a cell phone, it's just a pause.

And that -- because that is not the reason we have these issues, but it is a factor.

STEPHANIE SY: Mountain Middle School first enacted the policy in 2013, when Shane Voss became head of the public charter school.

Where did cell phone use rank in your mind in importance?

SHANE VOSS, Executive Director, Mountain Middle School: I think it was really at the top.

We really wanted to teach students to dedicate their full energy and be present, and it started with the cell phones.

STEPHANIE SY: Eighth grade teacher Emma Boone was fully on board with the policy after she observed how cell phones affected students at a former school she worked at.

EMMA BOONE, Teacher: Because if they didn't know where to start with an assignment, rather than turn to a friend to ask for help or ask me for help, they'd just take out their phone and do something distracting to manage that discomfort.

STEPHANIE SY: Voss says the ban has cut down classroom distractions and increased student achievement.

But when it comes to mental health: SHANE VOSS: It's not a panacea to just look at phones and then all of a sudden everything will be fine.

I think there are a lot of factors that are attributed to this rise in anxiety and depression, but this has accelerated it, there's no question.

STEPHANIE SY: School cell phone bans are becoming more common across the nation.

Last year, Florida became the first to enact statewide phone bans during class at public schools.

Several other states are considering taking similar action.

JONATHAN HAIDT, Author, "The Anxious Generation": Academic achievement has been going down not since COVID, but since 2012.

As soon as the kids all had the Internet in their pocket, they can't resist.

They have to be using it.

STEPHANIE SY: Social psychologist Jonathan Haidt's book "The Anxious Generation has been near the top of bestseller lists for months, stoking debate around how smartphones and social media are in his words rewiring childhood and largely to blame for the youth mental health crisis.

JONATHAN HAIDT: This is the first time that a generation has faced a threat entirely on social media.

STEPHANIE SY: While Haidt declined our request for an interview for this story, he spoke to the "NewsHour" last year on the potential harms of social media.

JONATHAN HAIDT: There is direct correlational evidence that the more you use it, the more depressed you are.

It's especially heavy users, more than four hours a day.

Those girls are three times more likely to be depressed than medium users.

So it's anxiety and depression, also self-harming suicide.

All of those things skyrocket after 2012.

STEPHANIE SY: But Haidt and his argument are very much in the spotlight, and he's facing enormous pushback from other researchers, especially for two prescriptions he says are desperately needed for healthier childhoods.

JONATHAN HAIDT: One, no smartphone before 14.

That should be the minimum national norm.

Number two, no social media until 16.

DR. MICHAEL RICH, Founder and Director, Digital Wellness Lab, Boston Children's Hospital: There's no data behind that say that's when it automatically becomes safe.

STEPHANIE SY: Dr. Michael Rich is the director of the Digital Wellness Lab at Boston's Children's Hospital.

He studies the impacts of online media on kids' physical and mental health.

DR. MICHAEL RICH: He ignores a lot of the positives that have come with these technologies that kids have learned how to use in very positive ways to connect with others over great distances, to understand other cultures and other peoples.

So beyond just not being able to get rid of them, we probably shouldn't get rid of them.

What we really need to do is help our children of any age use these powerful tools in ways that are healthy, smart and kind.

DANAH BOYD, AUTHOR, "It's complicated": I don't think that a quick fix of taking the technology away or blocking people will do a darn thing.

I think that is about assuaging the anxiety of middle-upper-class parents.

STEPHANIE SY: Danah Boyd is the author of "It's Complicated.

The Social Lives of Networked Teens."

She also works for Microsoft Research.

What role do you think social media plays in anxiety and depression among teens?

DANAH BOYD: I think that the Internet mirrors and magnifies the good, bad and ugly.

I think it absolutely amplifies things.

And so I think that we have to acknowledge that, yes, young people are genuinely struggling, but trying to make the tools for which they're simultaneously exposed to the world and the tools for which they're reaching out to people unavailable isn't going to make the mental health crisis go away.

STEPHANIE SY: Boyd, a mother of three, says restricting technology could backfire, disconnecting vulnerable teens from supportive online communities, and make it more difficult for them to reach out for help during a mental health crisis.

DANAH BOYD: As a country, we have very few mental health resources for young people.

And most of them require your parents' insurance.

And if your parents are a part of the problem or you're afraid of telling your parent that you're struggling, you're not going to ask them for therapy.

STEPHANIE SY: I want to make certain that young people have the tools to be able to get help when they need it.

JEAN TWENGE, Psychologist, San Diego State University: We're not suggesting that everybody give up their smartphone or even everybody give up social media, just kids and the youngest teens.

STEPHANIE SY: Jean Twenge is a psychologist at San Diego State University and frequently collaborates with Jonathan Haidt.

She faced similar criticism back in 2017 when she published "iGen," a book that also made the argument that spikes in teenage depression could be linked to smartphones and social media.

JEAN TWENGE: It is seven years later, and we have a lot more data and teen depression has continued to go up.

And still we need to wait?

What are we going to wait for?

Teen depression is now at 20 percent.

Should we wait until it's half?

Should we wait until it's a third?

STEPHANIE SY: Ninety-five percent of American teenagers now have access to smartphones and about a third of them report being on social media almost constantly.

But several studies examining the impacts that's having on overall teen mental health have produced mixed results.

A report from the National Academy of Sciences in December concluded that, contrary to the current cultural narrative that social media is universally harmful to adolescents, the reality is more complicated.

Social media can offer both connections and a safe space for young people, especially for LGBTQ+ teens.

But it can also encourage harmful behaviors and take the place of sleep, exercise and other social activities.

Also, frequent social media use may lead to worse body image for some teen girls and make them more vulnerable to eating disorders.

AMBER BLANCHARD, Parent: I think my number one fear is social media for teens.

Back in Durango, Will and Amber Blanchard's two kids, 9-year-old Piper and 13-year-old Ben, are not allowed their own phones.

WILL BLANCHARD, Parent: We want to keep our kids engaged.

We want them to be active, just like the old saying, a tired kid is a good kid.

Go, Piper, go.

STEPHANIE SY: They believe this is what childhood should look like, family bike rides to a nearby river, where Ben practices fly fishing.

An occasional selfie on a parent's phone is called for.

The Blanchards aren't anti-technology.

But they say, in the absence of a smartphone, Ben has found an outlet in fishing and he's gotten really good at it.

AMBER BLANCHARD: He finds tranquility in being in the water.

And I just can't imagine him finding tranquility in a phone.

STEPHANIE SY: Both Ben and Piper attend Mountain Middle School, where the no-phone policy mirrors rules at home.

But even at the age of 9, Piper says she's noticed TikTok use outside of school causing problems.

PIPER BLANCHARD, Student: I have been seeing kids in other classes in fourth grade that's been on social media, and they have been trash-talking each other and they have been not friends anymore.

STEPHANIE SY: Ben says he has little interest in social media, but does think he's close to being ready for a phone.

BEN BLANCHARD, Student: For music, photos, texting or, like, communication with your parents or friends or family.

STEPHANIE SY: Is it that your parents have also kind of talked you through, like, their explanations for why you don't have phones and you trust them?

Is that what's happening?

BEN BLANCHARD: Yes, yes, very much.

I completely trust them.

STEPHANIE SY: All right, and they didn't pay you to say that.

(LAUGHTER) BEN BLANCHARD: I mean, the money would be nice, but... (LAUGHTER) STEPHANIE SY: While the science on smartphones and social media is still up for debate, Will and Amber Blanchard say they're only worried about what's right for their kids.

WILL BLANCHARD: What's best for one family, that's for them to judge.

That's for their choice.

And we have ours.

STEPHANIE SY: It's a choice millions of American parents are now struggling to make for their own families.

For the "PBS NewsHour," I'm Stephanie Sy in Durango, Colorado.