Children as young as four are now at school for up to 10 hours a day as work pressures leave families spending less time together than ever before, teachers have warned.
Family life is increasingly under pressure, with some mothers and fathers forced to put work above their children, according to a new poll.
School staff suggested that long hours in school or childcare are resulting in "ghost" children who do not talk to anyone, regularly fall asleep and are lagging behind their classmates.
The survey of around 1,300 school staff, conducted by the Association of Teachers and Lecturers (ATL), expressed concerns that childhood is being eroded by pressures on family life.
In total, more than half of those questioned (56%) said they believe that children spend a lot less time with their families than they did 20 years, while 74% think that parents and children have less time together than they did five years ago and 57% think they have less time together than just two years ago.
The vast majority (94%) thought that the main reason for this is because of parents working, while 92% blamed the use of technology.
Others said a cut in family time was down to parents prioritising other activities, changes to parents' work-life balance or changes to family dynamics, such as family breakdown.
One early years teacher who works in a North Yorkshire state school said: "Some children are placed in before and after-school care from 8am to 6pm.
"These children walk around like ghosts, do not talk to anyone, fall asleep frequently, do not progress as quickly as their peers. Their parents are also 'too busy' to support them in an adequate way at home."
And a primary school teacher from Kent said: "Many of our parents are commuters into London and therefore work long hours. We have children as young as four who are at school 8am-6pm, eating breakfast, lunch and dinner."
The findings come as ATL members prepare to debate a resolution on the issue at their annual conference in Manchester.
The motion warns that calls for youngsters to start school at an earlier age, along with proposals for longer school days and shorter holidays, do not put children first.
It says that strong families are the ''bedrock of a strong and stable society'' and that families need a work-life balance that allows them to spend time together.
Steve Wood, a state secondary school teacher from Kirklees, said: "The pressures on family time have grown considerably and work-life balance for many parents is an increasingly difficult area - the necessity to stay in work means time spent with children isn't always a priority."
And a primary school teacher from Bexley, south east London, said: "I feel that, through no fault of the parents, there is an expectation to work before looking after your family.
"Living costs mean it is unaffordable for only one parent to work, and there is less importance attached to bringing up children, with a detrimental effect on children and family life."
The ATL's poll found that 71% of school staff think that children should start school at age five or older, with just 24% saying that four is the right age to start school.
It also revealed that while most of those questioned (77%) thought that their current timetabled day was about right for the majority of their pupils, 18% said it was too long, leaving pupils feeling tired, having difficulty concentrating and even leading to more disruptive behaviour.
Asked how long a child should spend in timetabled education, half said that five hours a day at primary school was enough, while over a third (38%) said that six hours a day at secondary school was suitable.
Ministers have previously called for school nurseries to open longer, saying in the past they could only offer standard time slots for families, making it difficult for parents trying to combine childcare with work.
In a speech last week, education minister Elizabeth Truss said that action has been taken to allow all schools to cater to younger children and to open for longer hours to give families more flexibility.
Ofsted chief Sir Michael Wilshaw has called for more youngsters to start school at age two, suggesting that schools are best placed to help break "the cycle of disadvantage" and ensure that poorer children are not falling behind their classmates by the time they are five.
:: The ATL's survey questioned 1,343 education staff working in state and independent schools and colleges in England, Wales and Northern Ireland in March.
A Department for Education spokeswoman said: "Extending school nursery hours from 8-6 will give more flexibility to parents and enable more of them to use these high quality facilities to ensure their children start learning basic skills, such as number and letter recognition, from a young age. This can have a real and lasting impact on their development and life chances."