Violent and addictive computer games are luring youngsters into a fantasy world of drugs, murder and crime, a union leader warned on Wednesday.
It is also claimed there is a correlation between the video games and a "marked increase" in playground violence.
According to Alison Sherratt of the Association of Teachers and Lecturers (ATL) Pupils as young as four and five are acting out graphic scenes of violence in the playground and lashing out in the classroom after watching or playing inappropriate games.
The ATL junior vice-president said the addictive quality of video games can separate children from reality and leaves many at risk of social exclusion, obesity and living sedentary, solitary lives.
Many youngsters are watching material unsupervised that is inappropriate for their age, she added.
Sherratt is due to propose a motion to ATL's annual conference in Manchester raising concerns that some computer games have a negative effect on very young children.
It calls for ATL's executive to commission research which will allow it to lobby government for the introduction of "stringent legislation" on computer games.
In her speech, Sherratt is expected to tell delegates that she was inspired to put forward the resolution after watching her class in the playground "throwing themselves out of the window of the play car in slow motion and acting out blood spurting from their bodies".
Most of her class of four and five-year-olds have TVs and laptops in their bedrooms, she says, and many have access to or own games consoles.
Sherratt notes that there has been a "marked increase" in aggression in general over the last few years.
She adds: "We all expect to see rough and tumble but I have seen little ones acting out quite graphic scenes in the playground and there is a lot more hitting, hurting, thumping, etc, in the classroom for no particular reason."
She says that she has found evidence which shows that violent virtual games played extensively by teenagers can make them more aggressive.
"The games encourage aggressive behaviour because of the violent acts depicted in them," she is due to say.
Teachers need guidance on how to deal with children playing violent computer games, Sherratt claims.
She adds: "Obesity, social exclusion, loneliness, physical fitness, sedentary, solitary lives - these are all descriptions of children who are already hooked to games, so we are aspiring to my current class achieving this unenviable target?
"Yes, addictive quality of these games means that many children are already hooked into these fantasy worlds separating themselves from reality."
Research also suggests that children who continually play on games consoles can suffer from tendonitis and even seizures from an early age, Ms Sherratt says, and it could also impact on their speaking and listening skills.
She says she is not asking for a ban on computer games but for ATL to develop a policy that gives guidance to teachers and can be used to lobby government.
Speaking ahead of the conference, ATL general secretary Dr Mary Bousted said: "I think what we are talking about, first of all, is the amount of time children spend locked in their room.
"The fact that children spend hours locked in their rooms playing computer games, which means they're not interacting, they're not playing and not taking exercise."
Some of these games are "very violent", she said, and have an effect on "tender young minds of children and young people".
"If you have got a game in the house, it's very difficult to police who's playing it," she added.