The fix only takes about 18 minutes a night.

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Your child has a big test tomorrow. What takes priority: more studying or going to bed? Well, according to new research, letting your kid catch a few more Zzs might matter more when it comes to getting a good grade. Small increases of sleep—a little over 18 minutes every school night—were linked to grade improvements in elementary schoolers.

For the study, researchers at McGill University and the Douglas Mental Health University Institute created a sleep education program to be taught in three elementary schools. The curriculum focused on using age-appropriate methods to teach healthy sleep habits and hygiene. For example, first and second graders were shown a video about a boy who sleeps in an overly stimulating room and loses sleep. Overall, 71 students between the ages of seven and 11 participated in weekly two-hour interactive classes for six weeks. At home, parents helped to measure student sleep by affixing a monitor on the non-dominant wrist at bedtime for four weeknights. Parents also gave researchers their children's report cards at the beginning and end of the program.

At the end of the study, students slept, on average, 18.2 minutes longer a night than they did before going through the program. They also slept 2.3 percent better, overall. This translated into a significant improvement in mathematics and English grades, too.

Researchers conclude that sleep is an important factor in learning potential, and cooperation with both parents and educators is needed to make sure kids are getting enough sleep. Not sure how much shuteye your child should get? Here, 11 things every parent should know about kids and sleep.