Emma Mills-Rittmann quit Facebook because, she says, other kids ruined it for her.

"[Your friends] hang out with other people and they didn't call you," said the 14-year-old, who goes to St. John the Baptist Catholic School in Savage. "Then you see the pictures."

Minnetonka teen Allison Jensen knows the feeling. "When you see albums of people with all their friends and you're not in them, it kind of makes you feel left out," said the 13-year-old, who goes to Hopkins West Junior High.

Reactions like those are something researchers and pediatricians are watching closely as they try to understand a new cyber ailment -- "Facebook depression." Facebook's pervasive reminders of their friends' happiness can amplify the sadness other teens may be feeling, the American Academy of Pediatrics reported this spring.

Those cheerful words in Facebook status updates, happy faces smiling from photos or the climbing numbers of friend tallies can make teens feel lonely, inadequate or just plain sad. The problem is made even worse in the summer, when teens have more free time.

"It used to be, when we were growing up, a glance or an unkind word could put people in a depressed state," said Mark Hogan, guidance counselor at Susan B. Anthony Middle School in Minneapolis. "Now it's a constant barrage with social media that's updated in a moment's notice."

Instantly left out

Those constant updates about others having fun can be hurtful for young people who are already emotionally fragile and insecure simply because of their age, Hogan said.

The teens attest that the window on their friends' social lives that Facebook provides can be uncomfortable to see.

"I'll see pictures of friends I was supposed to hang out with one day and [I'll see] they're hanging out without me," said Robert Westfall, a 15-year-old from St. Charles, Mo., who was recently visiting the Mall of America in Bloomington.

Molly Giessing, 15, of Kirkwood, Mo., jumped in: "Especially with mobile uploads -- they take a picture and upload it, thinking I'm not going to see it. It's like, thanks for hanging out!"

"It kind of makes you wonder whether they're really your friends or not," added Emmy Nixon, 15, also of Kirkwood.

Mariah Rud, 15, a Farmington High School student, echoed her peers' experiences.

"If [friends] go to a party, it feels like, why wasn't I invited?" she said.

Virtual lives unrealistic

But often what kids find depressing are phony versions of their friends' lives that show up on Facebook.

Facebook users, teens or otherwise, use the site to project the best possible form of themselves, said Massachusetts Institute of Technology Prof. Sherry Turkle, author of "Alone Together: Why We Expect More From Technology and Less From Each Other."

"It's like looking at people in magazines, except they are your friends," she said.

A Facebook user would probably not share, for example, that a family pet died, she said.

"You have this steady stream of people going to parties and having friends and showing off beautiful vacation spots," she continued. "And there you are in your little life and your dog died. You know that your life isn't all parties and vacation spots. People do get depressed."

Summer is prime time for this depression to hit, Turkle said, because students are no longer focused on school activities.

But for some, the term "depression" is a bit extreme.

Aya Maruyama, a guidance counselor at Minneapolis' Thomas Edison High School, said that while Facebook affects her students' lives, she hasn't observed depression or anxiety as a result of the site. She said, instead, that Facebook "enhanc[es] the dramas within their lives."

Regardless of terminology, it's something to watch, Hogan warned.

For teens who are struggling or parents who are at a loss for how to address this issue with their kids, Turkle offers suggestions.

"Remind yourself that people are performing. Say to yourself, 'I know something about this medium that I am allowing myself to not put at the front of my mind when I am feeling down: People are putting down the life they want other people to see.'"

A good exercise, Turkle said, is to discuss with your teens what their own "perfect" summers might look like -- a collage of only the happy moments, purposefully leaving out the bad ones, like the dog's death.

"Explore with your teenager that Facebook isn't life and life shouldn't be lived on Facebook," she advised.

Jessica Bakeman • 612-673-4401