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KANSAS CITY, Mo. — A healthy diet and plenty of activity can help your child avoid obesity. You may not have thought about another way to lower the chances. It’s sleep with an early, consistent bedtime.

It’s naptime at YMCA Metro Head Start. Every day at 12:30, the three to five-year-olds are on their cots hearing a soothing song. Then it’s lights out. Little Sky’s mom says there’s also a consistent routine at home with a bedtime of 8 p.m.

“If we keep him up even 30 minutes later, the next morning, it’s difficult to get him awake. He’s moody,” said Sarah Fortier.

Researchers followed nearly a thousand children and found another big benefit in having pre-schoolers in bed by 8 p.m. Only 10 percent of those kids went on to become obese teens compared to 16 percent of those who went to bed between 8 and 9 and 23 percent of those who went after 9.

“In order to get the recommended amount of sleep for preschoolers which is 11 to 13 hours of sleep, you really do need a bedtime by 8 p.m.,” said Dr. Meredith Dreyer, a clinical psychologist in the weight management program at Children’s Mercy Hospital.

Dr. Dreyer said that adequate sleep is vital in regulating hormones that control appetite. What’s more, if kids are asleep, they’re not eating. She pointed to parents’ work schedules as an issue in some families.

“Kids are eating often two or three dinners because they eat with mom at 6 o’clock and with dad at 10 o’clock.”

She said good sleep habits for little ones will become habits that benefit them the rest of their lives. Good habits include no screen time for an hour before bedtime.

Fortier said she sometimes feels guilty not letting her son watch a cartoon.

“But no, we have to stick to that routine. It’s better for all of us,” she said.

And research shows a bedtime by 8 p.m. is better in preventing obesity. The study from Ohio State University is in the Journal of Pediatrics.

Dr. Dreyer said an 8 p.m. bedtime can be harder at this time of year when it’s light out, so she recommends light-blocking curtains.