It's even starting as young as kindergarten.

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Between college preparation and extracurricular obligations, high-school students are under a significant amount of pressure. But a new study suggests the heavy load is actually starting a lot younger than that—kids as young as five may be overworked.

The study, published in the American Journal of Family Therapy, found that primary grade children were spending triple the suggested time on their homework—and kindergartners, for whom the National Education Association (NEA) has not endorsed homework—averaged 25 minutes each night.

1,173 English- and Spanish-speaking parents of children grades K-12 participated in the study. They were given a 46-item questionnaire broken down into three parts: demographic questions, homework issues (amount received, parent engagement, etc), and questions regarding the child’s GPA, academic performance, stress, sleep habits, and chores.

The homework load was measured by using the National Parent-Teacher Association's and NEA's "10-minute rule," which recommends 10 minutes multiplied by the child's grade level as the allotted time for homework (so a first grader would have 10 minutes a night, a second grader would have 20, and a 12th grader would have 120). The study showed that the overall daily homework load increased as students progressed in grade levels, but that the increases were inconsistent. Interestingly, primary school children were spending more time on homework than expected—first-graders spent 28 minutes instead of the recommended 10—but high school students were spending significantly less (12th graders, for example, had half the anticipated load). 

The implications run deeper than stressed-out students. The study identified a positive correlation between homework load and family stress, and as parents' confidence in their ability to help their child decreased, family stress increased. In families with parents lacking a college degree, fights and conflicts over homework were 200 percent more likely to occur.

Children could also be missing out on other important developmental activities.

"The levels of family stress and tension found in this study fall into ranges that could lead to detrimental physical and mental health," Robert Pressman, the study's lead researcher, said in a statement. "The Kindergarten homework load was identical to that of first and second graders. In that period when children are focused on early stages of socialization and finessing motor skills, an overload of homework will likely interfere with a Kindergartener's ability to play and participate in extra-curricular activities."