The screen shows a montage of common images — a group of friends at a noodle joint, half glued to their mobile phones; girlfriends at a Colorado Rockies baseball game posing for selfies. Cut to a group of middle schoolers sitting on a park lawn. A boy with glasses and wiry sandy hair says screen time “distracts you probably from what’s more important and yet you still can’t get off of it.” A slim, ponytailed girl adds, “It pulls you in.” The boy agrees strongly, “It pulls you in."
It’s a common observation. When physician and filmmaker Delaney Ruston found out that kids spend an average of 6.5 to 8 hours a day looking at screens, as a doctor she wondered: “What impact does all this screen time have on health?”
Ruston investigates this question in her documentary Screenagers, which explores how young people use digital devices and the possible effects on their brains. She discovers digital media use can produce a drug-like effect, felt at any age but most intensely during the teen years. When parents abruptly take away the device from their child, a meltdown typically ensues. “I think so many parents are feeling out of control,” Ruston says.
We spoke to Ruston and other experts about the health effects of screen time from childhood through adulthood.
A 2014 Nielsen report found that adults log a total of 11 hours of screen time a day. Here are some of the ways this might be affecting our health:
- Vision. Staring into a screen for extended periods of time can cause “computer vision syndrome.” You’re probably familiar with the symptoms: strained, dry eyes, blurred vision, and headaches. Poor posture can also cause neck and shoulder pain.
- Sleep. Studies link heavy computer and mobile phone use to more sleep disturbances. University of Gothenburg psychologist Sara Thomée, one study's lead researcher, says the blue light from digital devices suppresses the sleep-promoting hormone melatonin, keeping us from having restful sleep.
- Addiction and reward seeking. Dopamine, the “feel-good hormone,” is part of the brain’s pleasure and reward circuits. Playing video games turns on similar brain regions as those linked to cravings for drugs and gambling, Ditto for social media — every time we see a new post or get a reaction to ours, it’s like a hit of brain candy.
- Weight. Even two hours of TV a day can increase the risk of weight gain, diabetes, and heart disease in adults. (Computer use doesn’t seem to have as strong a link.) There are probably several factors to blame, including less active time, less sleep, and seeing more ads for unhealthy foods.
- Overall health. Most of the time we’re on our screens, we’re sitting down. Sitting for hours at a time boosts the risk of obesity, heart disease, type 2 diabetes, and some types of cancer. One study found that spending more than four hours a day in front of a computer or TV more than doubles your likelihood of dying or being hospitalized for heart disease — and exercise won’t reduce the risk. Check out our infographic for more information.
Tweens and Teens
During the preteen and teen years, the brain goes through major transformations. This may be why tweens and teens are especially vulnerable to the impacts of screen time on brain function and emotional well-being.
- Learning. One study found that kids and young adults who spend a lot of time on TV and video games were twice as likely to suffer from attention disorders. “Anything that affects attention affects learning,” says Victoria Dunckley, an integrative child, adolescent and adult psychiatrist and author of Reset Your Child’s Brain.
- Self-confidence. More time watching videos or other content on digital devices means less time exploring and creating their own experiences, stories, or art. “I think the key to develop self-competence and self-confidence is creating,” qualities important for healthy relationships and overall well-being, Ruston says.
- Social skills. Online experiences can build community and foster communication and creativity. But asScreenagers points out, tweens and teens might hide behind the screen to avoid tricky or awkward conversations, like approaching a crush or making new friends. “Rather than challenge themselves to do that in person, they go to the screen for a diversion,” Ruston says. That lack of face-to-face interaction can also feed online bullying.
- Emotions and personality. In 2010, researchers found that kids who logged more than two hours a day in front of a computer or TV screens had a higher chance of psychological difficulties on a standard questionnaire. Studies in young men show that playing violent video games is linked to more aggression and less sensitivity to others. Also, imaging studies have found that internet addiction and game addiction can shrink the brain regions responsible for planning and executive functions, empathy, compassion, and impulse control.,,, It’s unclear how quickly or easily the brain returns to a “normal” state after you stop playing video games, Dunckley says. On the other hand, games that reward cooperation and support can lower stress, boost mood, and promote helping behaviors.
- Addiction and reward seeking. A recent survey by Common Sense Media found that 50 percent of teenagers admitted being addicted to their mobile devices. Ruston learned that the brain’s dopamine center is extra sensitive during the teenage years, making the rush of playing video games feel even more intense and addictive.
- Sleep. Similar to the findings in adults, screen time can have damaging effects on sleep. A 2015 study of 10,000 16- to 19-year-olds in Norway reported that those who clocked in four or more hours of screen time a day (outside of schoolwork and homework) had about a 50 percent higher likelihood of lying awake for an hour or more before finally falling asleep. And according to a recent study, lack of sleep in teens is linked to more risky behaviours like drinking and driving.
- Weight and overall health. Just like in adults, watching two or more hours of TV is linked to weight gain in this age group. Studies have also noted higher cholesterol and blood pressure in kids who watch more TV.
Our kids are swimming in screens. According to a recent study, 92 percent of babies had used a mobile device before their first birthday. Nearly 35 percent have their own mobile device at age 2 and that number is 75 percent among 4-year-olds. Nearly a quarter of kids ages 2 and under have TVs in their rooms, and at age 4, almost 50 percent do. On the other hand, the American Academy of Pediatrics Studies suggest that screen time may be affecting the normal development of fundamental learning, language, and emotional skills.
- Learning. Kids younger than 30 months have a limited ability to learn from video, according to some studies., They learn more from live interaction with people and immediate feedback. The American Academy of Pediatrics discourages media use by children under 2 and says there is no proven educational or developmental benefit at this age. Screen time also takes away from unstructured play time, which is important for learning and problem solving.
- Language skills. Research has shown that TV can hamper language development in kids by displacing time spent interacting with caregivers. Digital devices might have a similar effect. “TV reduces speech between parents and their infants and toddlers,” says David Hill, chair of the American Academy of Pediatrics Council on Communications and Media Executive Committee. “It’s really that casual, everyday speech that helps them develop language skills.”
- Emotional development. Some experts worry that using digital devices as “shut-up” toys to occupy kids during day-to-day tasks like grocery shopping or eating out might prevent them from learning how to regulate boredom, distress, and other impulses and emotions.
- Vision. In recent years, many countries are experiencing epidemic levels of myopia, or short-sightedness, and indoor time may be to blame. In Seoul, South Korea, for example, 96.5 percent of 19-year-old men wear glasses. Researchers think it may be due to lack of exposure to sunlight, which might be important for proper eye development. In a 2013 study, teachers at a Taiwanese school made kids stay outside for their entire 80-minute recess period (instead of letting them stay inside). Only 8 percent were diagnosed with myopia a year later versus 18 percent at a neighboring school.
- Sleep. Research has linked screen use among children with shorter, lower-quality sleep. A 2014 review paper of school-aged kids and adolescents correlated screen time with poorer sleep. They saw especially strong links between screen time and delays in bedtime, as well as a shorter period of time spent asleep.A study published a year later found that compared with kids who didn’t sleep near a small screen (like a cellphone screen), those who did sleep near a small screen reported about 20 fewer minutes of sleep and were more likely to report insufficient rest or sleep.
- Weight. Several studies have found that the more TV children watch, the more like they are to be overweight. Kids with TVs in their bedrooms are more at risk, and childhood TV habits affect the risk of being overweight as adults.
The common theme across age groups: More screen time means less time for activities that are good for your health and well-being. The most important question to ask yourself is, “What is screen time displacing?” Hill says. “Is it displacing sleep, communicating with each other as a family, exploring the world and exercising?”
Ready to kick your screen habit? See our tips for adults and families.