Research shows children's lives are being "scholarised", with their parents compelled to convert their homes into educational establishments to help with homework.
The opportunities for time to play in school have also been reduced as schools give more time to national curriculum basics.
The introduction of extended schools, including breakfast and homework clubs and after-school day care centres has left children with little time to themselves.
Berry Mayall, of London University's Institute of Education, said: "This idea of children's lives becoming scholarised has been around for some time, but the pace has accelerated since the introduction of extended schools.
"Schools are also feeling more justified in making interventions into family life, when the home is understood to be a private and separate place.
"I know a mother who was contacted at half-term and told to help her child with catch-up work. This raises the question: is half-term a holiday or not?"
Ms Mayall said government initiatives failed to take into account children's right to time when they are not "told what to do" by adults.
Views differ among educationists and parents about the extent to which school should encroach on children's free time and the nature of homework set for young children.
Mick Brookes, general secretary of the National Association of Head Teachers, said the Government had created a climate which eroded children's chances for fun and play. He criticised the trend to set formal English and maths exercises for homework, rather than more imaginative projects such as estimating the amount of water used in the pupil's house.
"The balance is tilted too far and the pressure is put on far too young," he said.
Nicolas Tucker, an educational psychologist and former lecturer at Sussex University, said he doubted children would be adversely affected by recent trends towards more homework and extended schools.
"There have always been pushy parents," he said, "John Stuart Mill was learning Greek by the time he was 3.
"I don't think children have less leisure time now than before. They used to get sent up chimneys.
"The test really is how children feel, and those I meet seem to me to be having a good time."
This view was echoed by Ed Balls, the Children, Schools and Families Secretary, in a report this week in which he said the "vast majority" of children feel happy and safe. He rejected claims that they were weighed down by toxic influences such as drink, drugs and the pressures of school testing.
But although many parents put a strong emphasis on academic work in the home, research has shown there is huge variation in attitude.
A report from the Joseph Rowntree Foundation in September found that many children at a school with a high number of disadvantaged pupils complained that they were distracted by smoking, banging, swearing, loud music and television. A fifth of pupils at the school said they got no help at all with their school work.
- For more information on the Primary Review's latest findings, go to www.primaryreview.org.uk and click on 'Children's Lives Outside School and Their Educational Impact'.
The latest Review reports at a glance
- Primary pupils think the purpose of school is to prepare them for a job.
- They think it is more important to prepare fully for key stage 2 tests than to understand what their lessons.
- Pupils tend to be unhappy in groups that separate them from friends or where they are over- or under-stimulated.
- In Year 6, maths is the subject most enjoyed by boys and least enjoyed by girls.
- Social class is a key influence in parent-school relationships.
- Teachers still view the ideal family as being white, middle class, without special needs and with heterosexual parents. Children who require social services are seen as deficient in relation to this ideal.
- Teachers need to establish more fruitful links between home and school, capitalising on the educational possibilities of the home.
- But homework, extended schools and other out-of-school activities are eating into children's free time. There is also a trend away from scheduled play within the school day.
Relax and learn
An hour a week is the Government's recommended amount of homework for a pupil in Year 5, writes Irena Barker. But for Carolina Masters, 10, it usually takes longer.
Even if her teacher tells her to spend 20 minutes on something, her desire to complete it properly and please her teachers means it can end up taking an hour and a half.
Steve, her dad, has tried to help her with some commonsense short cuts for her maths problems, but he says she is a "stickler for rules" and takes it all very seriously. She insists on showing her workings out as her teacher has explained.
"I'm trying to teach her to use her initiative a bit more," he said.
"I welcome homework, but the problem seems that some children are taking it very seriously, even if their parents are relaxed.
"There is a strong sense of discipline in the school, and the problem is that they are not told enough by teachers that it isn't that important.
"I never had homework at primary school."
Mr Masters, who has another daughter, Ana, aged 5, edits the parents' online forum www.UKparentslounge.com from his home in Reigate, Surrey. He said some parents are also responsible for taking homework too seriously.
"I know people who sound like a grammar school teacher when they speak to their children," he said.
"But you can teach your children a lot at home through singing and reading to them, or baking a cake.
"I sing the alphabet song."