Children over the age of two develop mental health problems from smartphones and tablets, scientists warn.
Just one hour a day, when you're staring at a screen can be enough to make children more anxious or depressed.
This could make them less curious, less able to complete tasks, less emotionally stable, and lower their self-control.
Although teenagers are most vulnerable to damaged devices, children under the age of 10 and toddlers still in development are also affected.
However, research shows that British zombie children spend almost five hours cheating electronic devices every day.
Children under the age of two suffer from anxiety and depression because they spend a lot of time on smartphones, researchers from the US warn, and parents and teachers should do more to slow down their online time
Researchers at San Diego State University and the University of Georgia say that the time you spend on smartphones is a serious but preventable cause of mental health problems.
"Half of the mental health problems develop in adolescence," said Professors Jean Twenge and Keith Campbell.
"It is necessary to identify factors that are related to mental health problems [able to be changed] in this population, since most are difficult or impossible to influence.
"How children and teens spend their free time is [easier] Change & #. 39;
Parents and teachers need to reduce the time children spend online or watching TV while they are studying, socializing, eating, or even doing sports.
Professor Twenge said her study, one of the largest of its kind, supports the American Academy of Pediatrics' set screen time limit – one hour a day for children ages two to five.
She also suggests using a similar limit – maybe two hours – for school-age children and adolescents, she added.
For a nationwide 2016 Health Survey, researchers analyzed data from parents of more than 40,000 US children between the ages of two and 17 years.
The questionnaire asked about the teenagers' medical care, emotional, developmental or behavioral issues and their daily screen time.
TEENAGER SWAP LIBRARIES FOR LIKES
One third of young people did not read a book last year, according to the study in August.
With the growing social media of a teenager, only 16 percent of 17- to 18-year-olds read a book a day for pleasure, compared to 60 percent at the end of the 1970s, according to a study.
In addition, only two percent of 15- to 16-year-olds read a newspaper daily, a decline of 31 percent compared to the early 1990s.
The results further suggest that between 2006 and 2016, the use of social media among young people increased by an average of one to two hours a day.
The main author Dr. Jean Twenge of San Diego State University said, "Compared to previous generations, in the 2010s, young people spent more time online and less with traditional media such as books, magazines, and television.
"Time on digital media has replaced the time she once spent enjoying a book or watching TV."
Researchers fear that decreasing reading rates among teens will affect their academic performance because they lack the focus on understanding textbooks.
The researchers analyzed the results of the Monitoring the Future study, which polls about 50,000 students aged 13 to 18 in the US every year.
Adolescents who spend more than seven hours a day on screens have twice as many anxiety or depression issues as those who have spent an hour.
The connection between on-screen time and well-being is stronger in adolescents than in young children.
Professor Twenge said, "At first I was surprised that the youth associations were bigger.
"Teenagers, however, spend more time on their phones and on social media, and we know from other research that these activities are more associated with poor wellbeing than television and videos, which is the largest screen-viewing time of younger children."
Even a moderate use of four hours is associated with less mental well-being than one hour per day.
Preschoolers or under-fives, who are high users, lose control twice as often – and are 46 percent more prone to not calm down when they are excited.
Among 14- to 17-year-olds, more than four out of ten (42.2 percent) of the students, who spent more than seven hours a day on screens, did not complete their tasks.
About one in eleven (9 percent) of 11 to 13 year olds who spent an hour a day on screens were not curious or interested in learning new things.
In the journal "Preventative Medicine Reports," the professors reported that they were particularly interested in links between screen duration and anxiety diagnoses and depression in adolescents who had not been thoroughly screened.
They said, "Earlier research on correlations between screen time and psychological well-being in children and adolescents has been contradictory, leading some researchers to question the screen-age limits proposed by physician organizations."
The US National Institute of Health estimates that children spend an average of five to seven hours on screens during their free time.
The adverse health effects increase.
This year, the World Health Organization (WHO) decided to include the gaming disorder in the 11th revision of the International Classification of Diseases.
And in December 2017, a team of researchers from Oxford University found that the average daily image time of zombie children in the UK rose to four hours and 45 minutes in just under three hours.
Experts warn that "addicted" children could risk insomnia, obesity and victims of cyberbullying, while losing valuable social skills due to the lack of personal contacts.