Getting young children into bed before 8 p.m. might reduce the risk of being obese in later life, suggests new research published in the Journal of Pediatrics.

According to researchers from The Ohio State University College of Public Health, putting preschoolers to bed later in the evening, especially after 9 p.m., is linked to a higher risk of becoming obese.

To assess the effect of varying bedtimes, the team looked at data from 977 preschoolers who were part of the Study of Early Child Care and Youth Development, a project that followed healthy babies born at 10 different U.S. sites in 1991.

Bedtimes for the children, who were aged around 4.5, were split into three categories. Around a quarter of the children went to bed at 8 p.m. or earlier, around half between 8 p.m. and 9 p.m., and the remaining quarter after 9 p.m.

The researchers then linked the children's bedtimes as preschoolers to the levels of obesity in the children 10 years later when the average age of the children was 15. The results showed that of the children who went to bed before 8 p.m., only 10 per cent were obese as teenagers.

However, this number increased to 16 per cent for those that had gone to bed between 8 p.m. and 9 p.m., and more than doubled to 23 per cent for those who had gone to bed the latest, after 9 p.m.

The study, which is the first to use data on obesity collected around a decade after the childen were in preschool, also supports the existing research on the impact of sleep on obesity.

Previous studies have also shown that the majority of young children are biologically pre­programmed to be ready to fall asleep well before 9 p.m.

Lead author Sarah Anderson commented that although putting children to bed earlier doesn't guarantee that they will immediately fall asleep, it does make it more likely that they will get the amount of sleep they need.

"For parents, this reinforces the importance of establishing a bedtime routine," she added, "It's something concrete that families can do to lower their child's risk and it's also likely to have positive benefits on behavior and on social, emotional and cognitive development."