A later bedtime has been linked to an increased risk of obesity for kids under the age of  6, according to a new study out of Sweden.

According to CNN, Dr. Claude Marcus, a professor of pediatrics at the Karolinska Institute in Sweden and an author of the study, which published Tuesday in the journal Pediatrics, says concerned moms and dads should focus on maintaining a regular routine when it comes to scheduling meal and bed times. Even though the researchers say parents shouldn't rush to put their preschoolers to sleep earlier, there is a link to obesity with a later bedtime.

The research focused on 107 children in Sweden, with 64 of the children having a parent who classified as overweight or obese. This study was part of a wider study on obesity. Researchers monitored each child's weight, height and waist circumference from ages 1 to 6. The study said all of the children had similar measurements when the study started. Using a tracker worn on the child's wrist, sleep was measured for seven consecutive days once a year for the length of the study.

The results of the study found that children who habitually went to sleep late, defined by the researchers as past 9 p.m., had a wider waist and higher body mass index by the end of the study. Dr. Claude Marcus suggested that staying up beyond 9 p.m. could be one sign of an overall lifestyle that puts kids at greater risk of being overweight. Marcus did note that kids' bedtimes around the world vary. Kids in places like Spain and some parts of Asia, according to Sleep Medicine, stay up much later than the study's cut-off time.

Even though the researchers were able to objectively measure sleep characteristics through the wrist tracker rather than relying on information relayed by parents and children, a major limitation of the study was the small pool of children used in it. Marcus says that the wrist tracker was more reliable than receiving information via parents.

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