We've all heard the recommendation of the American Academy of Pediatrics: just one to two hours a day of "quality" electronic entertainment for children over 2. Yeah, right. In 2010, a study in the American Journal of Epidemiology reported that most adolescents spend an average of 25 to 30 hours per week watching TV and using computers. And while half of parents surveyed in a 2010 study said they always or often set limits on screen time, 18 percent of their kids really disagreed.

"It's getting more complicated to measure how much screen time kids are getting," notes Lisa Guernsey, author of Into the Minds of Babes, a book about children's use of electronic media. "We're no longer talking about the TV in the den that parents can turn off. These days, many teens and tweens have smartphones, laptops, tablets, and iPods that they carry with them." When you add up the total time kids spend on their electronic devices, you arrive at a truly staggering number: The average American between the ages of 8 and 18 spends more than seven hours a day looking at a screen of some kind, reports a Kaiser Family Foundation study. "When we conducted a similar survey five years before, we thought children's screen time couldn't rise any higher," says Donald F. Roberts, Ph.D., a Stanford University communications professor who coauthored the study. "But it just keeps going up and up."

Scientists are now beginning to tease out the effects of all this electronic engagement. Too much screen time may be linked to an increased incidence of risky behaviors, and more social network activity seems to correspond to mood problems among teens. But there's good news, too. Moderate computer use may be associated with the development of some cognitive and social skills. Here, a closer look at the cons and then the pros of screen time:

WHEN TO WORRY

The more hours teenagers spend using a computer or watching TV, the weaker their emotional bonds with their parents, reports a study of more than 3,000 adolescents published in theArchives of Pediatrics & Adolescent Medicine. On the other hand, teens who spent more time reading and doing homework reported feeling closer to their moms and dads. "Strong attachment to parents" — a bond of understanding, trust, and affection — "is protective against poor psychological health and participation in risky health behaviors," the study's authors note, so "concern about high levels of screen time is warranted."

• No surprise here: Screen time can make a kid fat. Kelly Laurson, Ph.D., a professor of kinesiology and recreation at Illinois State University, asked more than 700 children to wear pedometers and report how much time they spent watching TV and playing video games. He found that a lack of exercise and a surfeit of screen time each contributed to kids' growing girth. "Kids are more likely to eat when in front of the TV, and TV shows lots of ads for unhealthy foods," says Laurson. "Too much screen use also interferes with sleep. These influences can make kids fatter and less fit, even if they are physically active."

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• Researchers at Queen's University in Canada found that youths with the highest level of computer use (more than three to four hours a day) were 50% more likely to engage in risky behaviors such as drinking, smoking, drug use, and unprotected sex than kids with minimal amounts. "More and more advertising has moved to the Web, and these ads are far less regulated than those on TV," says researcher Valerie Carson. "Kids who use computers can be exposed to many examples of dangerous behaviors, which they may then emulate."

WHY YOU SHOULDN'T STRESS OUT
• When your kid is immersed in a game, he or she is actually practicing some very complex — and necessary — skills. In a handful of experiments comparing gamers to non-gamers, scientists have found that frequent players have sharper vision and faster reaction times and that they're better at multitasking and less easily distracted.

• Though the precise skills honed by a video game may not always transfer to real-world tasks, and video game playing should be done in moderation and not take the place of physical exercise, the psychological habits fostered — determination, resourcefulness — may well carry over into players' everyday lives. And a study by Michigan State University researchers of nearly five hundred 12-year-olds reported that playing video games was associated with creativity in tasks such as generating stories.

• Screen time can foster connection and closeness with peers. Larry Rosen, Ph.D., a psychologist and the author of iDisorder: Understanding Our Obsession With Technology and Overcoming Its Hold on Us, found that teenagers who are more active on Facebook and other social-networking sites display more "virtual empathy" — they are more likely to express support and encouragement. "Behind the safety of the screen, teenagers — especially boys — are more willing to share their feelings, to take social risks," Rosen notes. "They are practicing emotional life on the screen, and getting better at it."

So screen time can have its bright spots as well as its dark sides. How can you, as a parent, make sure the former prevail? Turn to 3 Smart Ways to Handle Screen Time, and follow the expert strategies.

1. Don't get caught up in the idea of limiting screen time to a certain number of hours
You read that right: Many researchers now believe it's almost impossible even to keep track of tweens' and teens' total screen time, especially when they're out of the house for many hours a day. "How do you count the 30 seconds a kid spends checking his e-mail between classes," asks psychologist Larry Rosen, Ph.D., "or the zillions of three-word texts a kid sends throughout the day?" Instead, some experts suggest, consider establishing tech-free zones at the times and in the places you do control: No cell phones or handheld gaming devices in the car. No computers or TVs on at the dinner table. (Note: These rules should apply to parents, too.) No iPhones, iPads, or iPods during homework. And nothing that blinks or beeps in kids' bedrooms at night — collect electronic devices an hour before bed; return them in the A.M.

2. Consider your child's behaviors, both online and offline
Is your child meeting her obligations at school and at home? Does she have close, supportive friendships both online and face-to-face? These are the benchmarks that matter more than the sheer quantity of time your child spends in the company of electronic media. Indeed, young people who act out online in aggressive ways, such as engaging in cyberbullying, often have trouble keeping friends in real life, notes University of British Columbia psychologist Amori Mikami, Ph.D. Her research also found that teenagers who have healthy friendships in real life tend to use social-networking sites to further enhance those relationships.

3. Give your kids guidance on digital life just as you would on any other fraught activity