Experts warn parents how Snapchat can hook in teens with streaks

— -- Teens are on their phones more than six-and-a-half hours a day, according to the nonprofit Common Sense Media. More than half of teens text and nearly all use social media apps, and this daily behavior may not be entirely their fault.

Many games and social media apps are designed to get people “hooked” and keep coming back, Dr. Jodi Gold, the author of “Screen Smart Parenting,” explained to ABC News.

Take Snapchat, the super popular app among teens for sharing photos and video, which has mechanisms in place to incentivize teens to become daily users with a phenomenon called the Snapstreak.

Snapchat friends exchange a photo daily for three consecutive days to start a "streak." If one day is missed, the streak will expire. The app tracks the streak, upping the number next to the friend's name as the Snapstreak continues.

Experts like Dr. Jodi Gold say streaks can create a concerning hierarchy of friendship that can leave some teens afraid to disappoint others if they drop a streak -- or petrified about any change in status.

"This has become extremely important -- especially to teenagers," Gold explained.

It's become so important that 18-year-old friends Sherlana and Ray have a 405-day Snapstreak. That means they’ve been sending each other a photo of something every day for more than a year.

The two are so invested in their streaks that if they can’t get onto the app, they turn to their mothers to send snaps for them.

“When she sees that [hourglass] come on and she can't get onto the WiFi, you know, then she starts to panic,” Sherlana’s mom, Cindy Alphonse, told ABC News.

Snapchat told ABC News that Snapstreaks are "designed to be light-hearted and fun."

It's not just apps that suck teens in. Smartphone games like the popular strategy game Clash Royale, which has rocketed to the top of the charts, can be habit-forming.

Gold’s 11-year-old son, Carter Gold, says the game was so addicting for him that he had to delete the app from his phone in order to fully remove himself.

"They always try and pull you in more and then they kind of never let you leave until you finally quit it," Carter said.

Supercell, the maker of Clash Royale, told ABC News: "We want people to enjoy our games when they play them but we make it easy to leave if they don't."

Gold says the concern is not necessarily how many hours kids log on the apps, but how important they are to the teen’s self-worth.

“The more you cannot leave one day without being on social media, the more your identity gets wrapped up in it [and] the more likely it's going to have negative effects,” she said.