Flickr / guilherme jofili There's already a great deal of research suggesting kids should start their school days later. Now, new research finds they should probably start their entire school careers later, too.

A study out of Stanford University has found kids whose parents waited to enroll them in kindergarten by age 6 (instead of 5) had measurably better scores on tests of self-control by the time they were 7 and 11.

Self-control — known to psychologists as "executive function" — is one of the more important traits kids can possess in their early years. A strong degree of executive function signals kids are able to budget their time and maintain focus even when they're faced with distractions.

In the latest study, investigators Thomas Dee and Hans Henrik Sievertsen used the Danish National Birth Cohort (DNBC) study to collect their data. The DNBC included responses from 54,241 parents on measures of mental health when their kids were 7 years old and 35,902 responses when the kids were 11.

Dee and Sievertsen found kids who started kindergarten a year later than average students had 73% better scores on tests of their hyperactivity and inattention four years later.

"We were a bit surprised at how persistent the effect was," Sievertsen recently told Quartz.

Schools in Nordic countries aren't exactly strangers to enrolling kids in school later in life. In Finland, for example, it isn't uncommon for kids to begin formal schooling at age 8. Much of their childhood is spent either at home or in a form of pre-kindergarten, where the biggest emphases are on playtime and social skills. Traditional subjects don't enter the picture until later.

The approach seems to pay off, and well past their 11th birthdays. Students in Finland (and other Nordic countries) are some of the top-performing nations in the annual PISA education rankings, though they do still lag behind many of the academic-intensive countries in Asia.