Prior research had yielded mixed results on the benefits of a late kindergarten start. A new study took a different approach.

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If you’re planning to send your child to kindergarten next fall, perhaps you should wait.

A new study from Stanford University has found that kids who delay kindergarten for a year enjoy mental health benefits that last later into childhood.

In particular, children who wait show significantly lower levels of inattention and hyperactivity, the study found. The benefits persisted even at age 11.

Some previous studies have found no benefits to a later start.

“I think they were looking at the wrong outcomes,” said Thomas Dee, a Stanford education professor who co-authored the new study. “They looked at test scores, dropout rates and employment. We looked at psychological outcomes.”

A growing number of American parents wait an extra year before enrolling their children in kindergarten. The practice is known as “academic redshirting,” a term borrowed from collegiate sports, where athletes sometimes wait a year in order to practice and mature before competing on the field.

Dee co-authored the study with Hans Henrik Sievertsen of the Danish National Centre for Social Research. It was published by the National Bureau of Economic Research.

They used data from a national mental-health screening of children in Denmark and matched it against data from the Danish census.

“We were fortunate to have really unique data from Denmark,” Dee said. “What we found is that delaying had very large but very narrowly targeted benefits for kids, particularly on the measure of inattention and hyperactivity. On this particular score, kids who delayed kindergarten had really dramatic improvements.”

A one-year delay reduced inattention and hyperactivity by 73 percent.

While the finding suggests that a later start can be beneficial for some, Dee cautioned that every child is different.

“Parents shouldn’t use this study to suspend their own judgement,” he said. “There’s a lot of heterogeneity to kids. This study implies an answer that isn’t correct for every child.”

Some kids are socially, emotionally and intellectually ready for elementary school at age 5, and some aren’t, he said. And their readiness depends, too, on the type of kindergarten they are entering.

Children benefit from expanded access to pretend play, Dee said, but many kindergartens have become more formal and structured, more like first grade.

Those entering more academically demanding programs might be more likely to benefit from a delay, he said.