The poll of 5,000 parents with children at private and state boarding schools shows homesickness is just as traumatic for them as for their children.
The survey, by the Independent Schools Information Service, is part of a campaign to reverse the decline in the number of boarding pupils, down by one-sixth since 1990. Average boarding fees are now more than pounds 10,000 a year.
The report says its findings "lay to rest the notion that boarding parents are uncaring egoists who cannot wait to hand over responsibility for their children to others".
For many parents, it says, "successful results of boarding have been bought at some cost - not just financial but emotional and, for many, a kind of anxiety somewhere between doubt and guilt".
One parent said that, during the first term, her daughter was desperately homesick.
"We all found this an extremely difficult time," she said. "Despite her pleading to be removed, we persevered."
Two weeks into the second term, the problem was happily resolved by negotiating a new weekly boarding arrangement.
One in three parents believes that their relationship with their child improves because of boarding while only 7 per cent feel it deteriorates. Four out of ten are first-time buyers of boarding education, with neither parent having had any personal experience of boarding.
Most parents have to justify their decision to use a boarding school to other parents, particularly the parents of those who are 10 or younger. One in five children starts boarding before they are nine.
Parents choose boarding because they believe it makes their children more mature and independent. They are more interested in the many extra- curricular activities on offer than in a particular school's academic reputation
Six out of ten choose boarding after considering local day schools and around one-fifth of parents opt for them because they live overseas or serve in the armed forces.
Overall, only a quarter of parents are concerned about whether a school is co-educational or single- sex, though it is important for 59 per cent of parents in girls' schools.
The weekly letter home is apparently a thing of the past. Nearly half of boarders never write to their parents but almost all telephone home several times a term. Nearly a quarter telephone several times each week.
Parents gave a variety of reasons why their children enjoyed boarding. One parent of three brothers at preparatory school said: "The boys think it's cool to board."