Slouching posture, carpal-tunnel, neck strain, eye problems. The negative effects that technology use is having on humans’ bodies are surprising. Kids who spend much of their days in and out of school, their faces glued to digital screens, may be establishing bad habits early. And according to a recent study by a group of Australian education and psychology experts, kids are spending more time with technology than researchers previously thought, far surpassing the American Academy of Pediatrics’ recommendation that screen time should be limited to two hours per day.

The validity of the doctors’ guidelines is subject to question; even the study’s authors suggest adjusting the criteria to better align them with a world increasingly, and inevitably, inundated with technology. But pediatricians are closely monitoring the health risks associated with spending too time looking at screens, and they’re not yet convinced they should ease up the guidelines.

As part of the study, published Wednesday in the journal BMC Public Health, the team of researchers surveyed more than 2,000 Australian students ages eight through 16. The researchers gave the participants computerized assessments and asked them to estimate the amount of time they spent on the exam. The researchers’ intent was to understand how much time the kids were looking at all types of screens. The research marks the first time scientists have looked at students’ overall media use, according to the study. Earlier studies have focused specifically on how kids use just TV or only computers.

In fact, the study would suggest that many students worldwide are probably using technology much more than the recommended two-hours maximum every day. But that doesn’t mean they’re all using it in the same way. The researchers found big differences in how long the kids use screens depending on their age, their gender, and the activity type. Close to half—46 percent—of all third-grade boys, on average, use screens for more than two hours per day, and that usage increases to 70 percent of boys on average by the time they reach ninth grade. Fewer third-grade girls—43 percent—use screens compared with their male counterparts, but that rate jumps to surpass boys’ average usage in ninth grade, to more than 90 percent of girls.

This discrepancy surprised the researchers because other studies have found that boys interact with screens more than girls overall. The reason behind this anomaly is difficult to deduce, but Victor Strasburger, a pediatrics professor at the University of New Mexico School of Medicine, speculates "girls may have been doing more homework than the boys, and the boys may have been doing more sports [away from screens] or playing more video-games on hand-held devices."

For general web use—which includes any research conducted for homework—students of both genders follow a similar pattern: Though fewer fifth graders than third graders use the Internet for more than two hours per day, the across-the-board usage rate steadily increases from fifth grade up to ninth. Almost half of ninth-grade girls, for example, are surfing the web (not necessarily using social media) for more than two hours every day.

Strasburger says there’s no reason to think that the study would have had a different outcome had it been conducted in the U.S. In fact, he suspects that it’s "probably worse" in America, he said. And although some critics may point fingers at teachers who have integrated technology into the classroom—and might even condone excessive screen time— the Australian study shows that TV or movies, in-school Internet use, accounts for the majority of kids’ screen time.

The American Academy of Pediatrics is perhaps the most influential organization to recommend that kids between ages three and 18 use screens for a maximum of two hours daily; and kids younger than three should avoid screens altogether, the academy says. But that’s not because researchers think digital media is inherently harmful. "If used appropriately, it's wonderful," Marjorie Hogan, a pediatrician at Hennepin County Medical Center in Minneapolis, told NPR. "We don't want to demonize media, because it's going to be a part of everybody's lives increasingly, and we have to teach children how to make good choices around it, how to limit it and how to make sure it's not going to take the place of all the other good stuff out there."

But pediatricians that help make the academy’s recommendations have to take into consideration more than just the education and career benefits. A number of studies have correlated extended screen time with various negative health effects. According to the the pediatric academy’s website, "Studies have shown that excessive media use can lead to attention problems, school difficulties, sleep and eating disorders, and obesity. In addition, the Internet and cell phones can provide platforms for illicit and risky behaviors." More recently, researchers have discovered additional concerning effects, including changes in social behavior and even a disorder now called "text neck."

The Australian study gives rare, fleeting insight into how kids are using technology. Though that’s helpful to pediatricians and parents, some experts say it’s not yet enough information to merit a modification to the American Academy of Pediatrics’ formal recommendations.

The problem is that it takes years—sometimes decades—to parse out the long-term health effects of different technologies, much less craft recommendations for how to use them. "The media are so different and ubiquitous, it’s like a mission impossible to get a good handle on who is using what when for how long," Strasburger said.

Strasburger helped develop the guidelines that were published in 2001, recommendations that were based on research that was conducted two years before. With no smartphones on the market and computer use less widespread than it is today, Strasburger and his colleagues really only considered TV, games, and movies as "screen time." But, given the health studies available, they still adopted the same two-hour-maximum recommendation. Moreover, funding is notoriously tricky to secure for studies about long-term media use, and technology is changing faster than ever, so it’s almost impossible to come up with recommendations that are actually applicable to kids when they need them.

Ultimately, complying with the rule is still worth a try, the Australian study authors conclude. Though they’re often ignored, recommendations like the ones from the American Academy of Pediatrics can help parents encourage their kids to use technology responsibly, Strasburger said. "During the week when kids are in school, if they’re spending something like five hours in front of the TV, not outside playing or doing homework or interacting with you [the parent], that’s a problem."