(CNN) -- New research shows that some students are doing more than three hours of homework a night -- and that all that school work may be literally making them sick.
It may be tempting to dismiss this latest research, conducted in upper-middle-class areas, as yet another manifestation of the eccentricities of the affluent. This is, after all, the same demographic that recently brought us eye-roll-inducing news stories about $250-an-hour tutors who drill preschoolers on their ABCs and 1-2-3s.
Could it be that a few short years later those same tots have graduated to marathon homework sessions?
"The three hours of homework a night was an average, by the way," says Denise Pope, senior lecturer at the Stanford Graduate School of Education and co-author of the study published in the Journal of Experimental Education.
"We had kids in the study who were doing way more," as many as five hours in some cases. Even in schools that have a policy limiting homework, advanced placement and honors classes are often exempt.
The study surveyed more than 4,300 students from 10 high-performing public and private high schools in upper-middle-class California communities. The researchers sought to examine the relationship between homework load and student well-being and engagement, as well as to understand how homework can act as a stressor in students' lives.
Their findings were troubling: Research showed that excessive homework is associated with high stress levels, physical health problems and lack of balance in children's lives; 56% of the students in the study cited homework as a primary stressor in their lives.
"We found a clear connection between the students' stress and physical impacts -- migraines, ulcers and other stomach problems, sleep deprivation and exhaustion, and weight loss," Pope observed.
Pope's findings are particularly interesting when compared to recent National Assessment of Educational Progress data about homework trends for the larger population.
As it turns out, most students' homework load has remained remarkably stable since 1984, according to the Brookings Institute's 2014 Brown Center Report on American Education.
So what's going on with the kids from affluent families?
Pope and her colleagues focused on upper-middle-class, privileged schools because it is in these communities that the accepted value of homework is deeply and unquestioningly entrenched. Here many students describe schoolwork and the pressures of high academic performance as a dominating force in their day.
Pope found in her work with Challenge Success, a Stanford collaboration formed in response to increasing emotional and mental health issues in American students, that homework kept coming up as a tension point.
There were parents who wanted more homework and others who wanted less. There were parents who, if the teacher was not giving homework at the younger grades, would buy their own workbooks and hand them to their children. Pope even heard from parents lamenting that they had not seen their children over an entire holiday weekend because they were attempting to complete homework assignments.
"We realized that we need intervention around homework," she said, and not just with high school students. While the present study was conducted with high schoolers, "we have the same data from the younger years."
The researchers acknowledged the limitation of their reliance on students' self-reporting, but felt that it was important to explore the students' firsthand descriptions of their experiences with excessive homework.
And while some of the grousing about having too much homework and feeling stressed out may seem like typical adolescent complaints, this latest study joins a growing body of research that paints a disturbing tableau about the unrelenting pressure on privileged children.
That children growing up in poverty are at-risk for a number of ailments is both intuitive and well-supported by research. More difficult to believe is the growing consensus that children on the other end of the spectrum, children raised in affluence, may also be at risk.
Suniya S. Luthar, professor of psychology at Arizona State University, dismissed the hesitation.
"When you say that poverty is a risk factor, that doesn't mean that all poor kids are troubled," she said. "It's exactly the same for upper-middle-class children of upwardly mobile families. All we are saying is that a larger proportion of these children are at risk, as compared to the average American community."
Luthar's rigorous (and fascinating) research first sounded the alarm on how youth from upper-middle-class communities are at risk for a number of serious disturbances, including drug and alcohol abuse, depression and anxiety.
The reason: an enormous amount of pressure, including "family dynamics, peer norms, pressures at schools, and policies in higher education," writes Luthar in a rigorous analysis, "I Can, Therefore I Must: Fragility in the Upper Middle Classes."
These findings have implications that go far beyond homework, stress levels or even health. They are also part of a larger cultural conversation about the profound downsides of our all-work, no-play, winner-takes-all society.
In the meantime it is important to keep in mind that the single most robust protective factor for chronic and potentially toxic childhood stress is social and family support; that is, a responsive relationship with an adult caregiver.
"Parents' first responsibility is to the health of their child," Pope says. "Parents need to be advocates and cheerleaders, not graders and correctors. And you certainly don't want to say to your kid, 'Give me half of the homework!'"
What's the magic number when it comes to homework?
"In high school, nothing over two hours. In middle school, no more than 90 minutes," she replied.
What about in elementary school? "There is no correlation between homework and academic achievement in elementary school."
But what about those nonacademic skills teachers talk about, like a sense of responsibility? Doesn't homework in the early years teach children how to become more organized and to meet deadlines? The research doesn't show that, Pope says.
"Look, we're not talking about picketing," observed Pope. "Parents need to advocate for their children with the tools and numbers and research in hand. We're talking about respectful dialogue."