Sleep four hours and you pass; sleep five hours and you fail.” So goes the mantra of every child dreaming of making it into a top South Korean university and grasping the ticket for what most South Koreans believe will mean wealth, job security and even Mr or Mrs Right.

It’s the same troubling maxim that keeps a multi billion-pound industry on its legs - private, extra-curricular tutoring, known as “shadow teaching” in South Korea. Intensive and thriving more than ever, nearly all school age children, and many nursery age, now attend some form of “hagwon” cram school.

According to the United Nations, this increased zeal for cramming is stealing the childhood of a whole generation, damaging young minds and crippling Korean society. And the frenzy is all down to the unrealistic expectations of South Korean parents, says Dr Andrei Lankov, a professor at Kookmin University in Seoul, and an expert on Korean affairs.

“The cram schools are popular because Korean society is designed in a way that makes college admission extremely important. Graduates of second-rate colleges, irrespective of their abilities and motivation, would never be seriously considered for first-rate jobs,” Dr Lankov says.

“In Korea, your career ceiling, your income, your choice of marriage partners and your lifestyle is determined by a university you manage to get in.”

To opt out of the cramming culture could mean fewer chances down the line, perhaps even none, Dr Lankov adds. “Korean society does not leave many alternative avenues for individual ambitions: you want to become somebody, you must go to a top school. Otherwise, you are a failure. Everybody knows it.”

The result is that South Koreans have little confidence in their public education system. The received wisdom is that no state school system in the world, and certainly not one with some of the most crowded classrooms (an average of 32 pupils per class in elementary schools, compared with the Organisation for Economic Co-operation and Development average of 21.5), could possibly prepare students for the super tough entrance exams that each top university sets.

And where the state has failed, parents are prepared to spend half of their income, often more, on extra-curricular studies for their offspring, even if it means pupils do not get to bed until way past midnight. But why not use that money to educate their children at a full-time, daytime, private institution?

According to Professor Songhua Lee of the Chung-Ang University Department of Education, a series of populist governments have been under such pressure to provide a seemingly level playing field that private school education has been stymied over the years.

“Unfortunately, we do not have expensive independent schools as you do in the UK. The tuition of these schools is under strict government control. An absolute majority of politicians in this country would not dare to legalise a kind of private schooling system (like the UK’s) because they want to look like Robin Hood,” he says.

In this spirit, successive governments have paid lip service to the ill effects of the cram school system, even going as far as to ban them at one time. But for some, bearing in mind that most of the government graduated from top universities, the system works - and those people are keen to see the status quo maintained. The fact is those at expensive cram schools nearly always end up at the “right” university and the best jobs, so it would take an enormous cultural shift to change things.

“Korean parents have a strong conviction that the normal life of their kids should be sacrificed for the enormous future benefits resulting from their advancing to prestigious colleges,” says Professor Lee.

“I certainly don’t agree with them. But I can’t persuade them not to think that way although I am an expert in the field of education.”

The reality is that pupils and parents alike have increasingly come to view day schools as safe, if dull, places where children can catch up on sleep. Sustained evening cramming for the sacred, revered entrance exams is where the real action is, and South Koreans spend four times more on average on private education than their counterparts in any other major economy, according to government figures (see box, page 21).

The university entrance examination, the College Scholastic Ability Test, is so important that flights are delayed to hush the air when the tests are given. And an increasing number of Korean parents have their children adopted by Americans working for the US military to enrol them at American schools on Army bases. High English scores are essential to pass university exams. Some families even relocate abroad, leaving Dad at home to finance the venture, in a bid to improve their child’s grasp of English.

Any edge, including feeding your children Ritalin and giving them plastic surgery to look more “intelligent”, is welcomed by some Korean parents. Eye jobs (making eyes appear bigger) are a favourite high school graduation gift from parents. Nose jobs are also popular. Parents reason that in ever-competitive Korea an advantage, however skin deep, is still an advantage.

The result is that children who now on average spend most of their evenings at cram school or taking other lessons such as music classes are becoming “nocturnalised”, according to one psychologist, as well as becoming overweight and physically weaker as they cope with the demands of near 24-hour education.

Misguided or not, parents and even many pupils see the system as the only way for the able and less able to realise a type of academic excellence, given that the state schools are not interested in nurturing excellence or competition, according to Professor Lee.

“Due to the equalised system of school, especially high schools with only a few exceptions, class instructions are focused upon `the average students with the average level of academic ability and performance,’ which automatically excludes the pupils at the top as well as those at the bottom,” he explains.

“No wonder parents and pupils are not satisfied with the educational service their schools provide.”

Cram schools on the other hand, he points out, offer differentiated and personalised instructions based upon the different intellectual levels and abilities of different pupils. Their educational service is more customised and their outcome more satisfactory. Instructors are under constant evaluation, and are always keen to respond to the feedback of pupils and parents in order to satisfy their needs.

Ms Chaeeun Lee, who teaches maths at a hagwon in Ulsan agrees that cram schools offer a better education, but says they are in danger of “stealing” the job of education from the public schools, costing families and their children’s well-being dearly.

“I’m hoping we will see a return to good education at public schools, and, even though I am a cram school teacher, I have to say, I want to see the end to some really bad practices, such as sending four-year-olds to cram schools. Changes are happening, all be that very slowly,” says Ms Lee.

Although Ms Lee works in the private sector she is typically paid less than her public school counterparts for longer hours. The conditions can also be uncomfortable as the hagwon schools place an emphasis on profit rather than staff well-being.

Apart from a handful of star teachers who earn millions from sales of DVDs, podcasts, and internet-based learning, low wages for the more demanding job of hagwon teaching are helping make cramming schools exceedingly profitable, raking in pound;5.9 billion annually. The best schools charge upwards of pound;600 a month per subject - a small fortune in a country where the average annual income is pound;20,000.

So profitable and powerful a lobby are the cram schools, that they are now pitched in battle against government policy, advocating extra free and paid-for lessons after hours in public schools. One of the principals leading this charge is Kim Yeong-suk, of Duksung Girls’ Middle School in Seoul. She successfully persuaded 30 of her colleagues to say goodbye to their free evenings and volunteer themselves for the new 7am to 10pm-plus day without overtime.

Children, for their part, were told to drop cram schools, which had at least given them a change of air once a day, and told to prepare themselves for studies until 9pm every day and even Saturdays. So far the academic results have been good. This could mean that more parents will line up to sign their children over for more hours at regular school, even, under some new schemes, by paying the schools to tutor after hours.

Until more national schools make this change, parents will continue to send their children to cram schools. Hyo Suk Kim, the 38-year-old mother of an 11-year-old, will continue to send her daughter to cram school and would even increase her hours of hagwon study if she had the money.

“National schools simply do not produce the exam results we are looking for. Passing the exams is everything to us; the cram schools have a good record in producing results so why should we change our tactics?”

Such is the need to cram constantly to pass exams; the whole point of education has been forgotten. In a generally conformist and deeply materialistic society such as South Korea’s there is little talk of expanding consciousness, the getting of knowledge or nurturing the individual.

“Too many Korean people cherish a myth that the diplomas from prestigious universities will guarantee material success and social privilege that are considered to be more important than self-accomplishment and quality of life,” says Professor Lee.

“Politicians, as populist as ever, urge the government to intervene and control the market of shadow education by discouraging universities to select pupils on their academic abilities, and by vilifying a small number of high schools that are allowed to require applicants to take entrance exams. Some are even going for abolishing those high schools. They are trying to replace ability-based selection with lottery.”

The latest generation of pupils has grown so used to the status quo that when the government tried to ease the pain of cram schools and the frenzy for exams, they planned street protests that were then banned.

“I often feel so sad, angry and very bored and many times I have vowed to quit hagwon. But then I think, “If I can get high scores in tests I can go to good university, so I’ve learnt to be patient’,” says Da-sol Jung, a 15-year-old pupil of Ms Lee’s, who says hagwons are bad but she needs them.

Unfortunately for an ambitious South Korea, such exam-focused rote learning at the expense of creative thinking is resulting in a less than competitive workforce and some very unhappy Koreans. South Korea now tops the world in the suicide table, while according to Swiss-based International Institute of Management Development, South Korean university education ranks near the bottom in the world in terms of meeting the needs of a competitive economy.

So what is the next step? “We urgently need two things,” says Professor Lee: “First, schools should be improved and teachers should be held more responsible for what they are doing. Schools have to be given with more autonomy from government control, and the private sector of education should be increased.

“Second, we need to develop a more diversified student selection system for universities, founded on a comprehensive evaluation of applicants’ abilities and characters both in scope and depth.”

If Professor Lee’s recommendations ever take shape, then perhaps Korean children might find their lives worth living again and the four-hour sleep mantra remembered just as a bad dream.

The multi-billion dollar cramming business - in figures

• There are 100,000 more instructors at private cram schools than there are actual teachers in schools.
• At least 600,000 people earn a living in the hagwon sector in South Korea - about 2.2 per cent of the working population.
• The cramming business generated pound;5.9 billion in revenue last year.
• Private after-hours education for elementary pupils accounts for 46.6 per cent of the industry’s total income.
• The average hagwon took pound;83 million last year, with crammers in the prestigious Gangnam area in Seoul south tripling the industry average with sales of pound;254 million each.
• Household spending on private education rose 7.3 per cent last year.
• Average monthly income is pound;1,600 and parents spend between pound;150 a month and pound;350, which can equate to as much as 22 per cent of their salary.

• Figures converted from Won.