Parents have been warned to "regain control" of their own households in the face of a growing tendency of children to sit for hours every day in front of computers and the TV.
Psychologist Dr Aric Sigman said a generation of children is developing a lifelong habit and in some cases dependency on small screens because of over-exposure in childhood.
Average screen time for young British adolescents is now at 6.1 hours a day and rising with 10 to 11-year-olds having access to an average of five screens at home, he will tell a scientific session of the Royal College of Paediatrics and Child Health (RCPCH) annual conference.
By the age of seven years old a child born today will have spent one full year of 24 hour days watching screen media, he will tell the conference in Glasgow.
Dr Sigman said even average levels of daily screen viewing were now strongly associated with a significantly increased risk of type 2 diabetes and cardiovascular disease.
He added that there were concerns that extensive computer game playing in children may lead to long-term changes in the brain's circuitry that resemble the effects of substance dependence.
"Technology should be a tool, not a burden or a health risk," he said.
"Whether children or adults are formally 'addicted' to screen technology or not, many of them overuse technology and have developed an unhealthy dependency on it.
"While there are obviously a variety of different factors which may contribute to the development of a dependency - whether it involves substances or activities - the age, frequency, amount of exposure along with the ease of access and the effects of role modelling and social learning, all strongly increase the risk.
"All of these contribute to a total daily exposure to, or 'consumption of', an activity.
"And all are prerequisite factors that contribute to the risk of dependent overuse of technology."
Dr Sigman said parents should not fall into the trap of "passive parenting" in the face of the problem.
He said rules and limits should be enforced on screen time for children. He added that the age of first exposure to the small screen should be raised to at least three years old.
Parents who constantly check and use smartphones and iPads in the presence of their children may be adding to their children's overuse of the small screen, he said.
Tips on how to instill good behaviour in your child from an early age by using the 'positive discipline' approach, as advocated by the National Society for the Prevention of Cruelty for Children (NSPCC).
You can never spoil your child by showing them too much love. Boost their self-esteem by making them feel cherished, safe and special.
Have clear simple rules and limits. Your child needs to know what the boundaries are, what is and is not acceptable. Keep it simple to avoid confusion and concentrate on behaviour that really matters.
Praise good behaviour that you want to encourage and chances are, your child will repeat this as they know there's a reward at the end of it.
If you ignore behaviour you don't like, it is less likely to be repeated by your child. Make it clear that you're open to communication when they are behaving, but not when they are being naughty or disruptive.
Rather than telling your child off for being bad, identify what they have done wrong and criticise the behaviour instead. Direct criticism can cause your child to go into their shell and become shy and withdrawn.
Be as demonstrative as possible. Sweep her off her feet and praise her to when she's been a good girl. She'll remember how happy it makes her feel and make her want to be good again.
If it looks as though your child's behaviour is starting to deteriorate, step in before things go wrong. Redirect them to another activity to avoid conflict. Acknowledge your child's feelings by saying, 'I know you are cross" but make it clear that it doesn't go beyond that point.
Children need to learn about dealing with choices and decision-making. Don't impose your decisions on them all the time, let them have their say on little things and gradually increase this as they get older.
Never use threats or physical behaviour, as this will only make the situation worse. Negotiate solutions when there is a disagreement and remember to communicate to help dissolve the problem. This way, your child will end up understanding what went wrong and why you are upset with them.
It's vital for parents to be positive role models for their child and practice what they preach. Actions speak louder than words. Let your child see that rules apply to everyone in the family, not just him or her.