Children who spend more time watching TV, using computers and playing electronic games have more family problems and are more likely to be obese, warn researchers.
Two new studies suggest the growth in use of electronic media devices such as tablets and laptop computers by children spells trouble for their emotional and physical health.
For every hour of screen time, the risk of family life being disrupted and children having poorer emotional wellbeing may be doubled, say Australian researchers.
Children whose mothers fail to impose rules restricting screen time are more likely to be fat, according to a U.S. study.
British experts said the latest findings strengthen calls for guidelines on maximum daily limits on screen time for children.
In the U.S., paediatric guidelines recommend that total screen time should be limited to less than two hours per day of educational, nonviolent programmes.
There are currently no formal guidelines in the UK.
More than 3,600 children took part in a study looking at the use of electronic media between the ages of two and six years, and the wellbeing of children two years later.
Questionnaires were used to measure six indicators of wellbeing, including emotional and peer problems, self-esteem, emotional wellbeing, family functioning and social networks.
Poorer wellbeing was found among those with higher screen time, with the risk of emotional problems and poorer family functioning rising with each additional hour of electronic media use.
The extra risk ranged between 20 per cent and two-fold depending on the aspect of behaviour being measured.
Watching TV appeared to be linked with poorer outcomes than playing electronic games or using computers.
Researcher Trina Hinkley of Deakin University, Melbourne, said: ‘Higher levels of early childhood electronic media use are associated with children being at risk for poorer outcomes of well-being.’
In a separate study, researchers at the Oregon Social Learning Center, Eugene, analysed parental monitoring of their children’s exposure to electronic media and the link with the Body Mass Index (BMI) – the score used to assess overweight and obesity.
The study included 112 mothers, 103 fathers and their 213 children aged five, seven and nine years.
Less monitoring by mothers of the time children spent watching TV or playing video games was linked with higher BMI at age seven and greater weight gain over time.
Monitoring by fathers had no effect.
Researcher Stacey Tiberio said mothers who failed to monitor their kids’ time on screen were not generally disinterested or uninvolved in their activities – they just didn’t think it was important.
She said: ‘The association between lower maternal media monitoring and higher child BMI was primarily explained by a tendency for these children to spend more hours per week watching television and playing video games.
‘This supports the validity of our interpretation that child media time has direct effects on BMI, is under substantial control by parents, and therefore is a prime target for family intervention.’
The studies call for more research into possible reasons, although some experts claim they could include physical inactivity, later and more irregular bedtimes leading to less sleep and greater exposure to food advertising.
Both studies were published in JAMA Pediatrics.
Dr Gavin Sandercock, Senior Lecturer in Clinical Physiology, University of Essex, said: ‘We know that obesity runs in families and this paper shows that the parents of children who get fatter from five to 10 years old are less likely to have rules around TV and screen time.
‘In particular, the study reports that mums who don’t monitor their young children’s screen time may be putting them at risk of becoming overweight or obese.
‘Children whose screen time wasn’t monitored watched more TV and got fatter more quickly than those living in families with rules around screen time.
‘This offers a mechanism to link screen time and fatness and suggests that inactivity comes before obesity in a child’s life.
‘The results go against the idea that fatness leads to lower activity levels and suggest that the UK should adopt guideline daily limits on TV and screen time as seen in the US or Australia.
‘The screen time reported in this study was 1h 45min per day which is much lower than the values for children in our own studies – within which 40 per cent of boys and 20 per cent of girls exceed 2h per day,’ he added.
Professor Lynne Murray, Research Professor in Developmental Psychopathology, University of Reading, said findings were not clear cut from the study on screen time and children’s emotional wellbeing.
But, she added, they were similar to other research and ‘although it might make for uncomfortable reading, it’s important to take the message on board.’