Later bedtimes linked to obesity risk in children under six

Photo: Getty Images/iStockphoto
Photo: Getty Images/iStockphoto 

Going to bed late as a child may be linked to an increased risk of obesity, finds a new study.

According to the research published in the journal Pediatrics, no matter how much a child slept, going to bed after 9pm was associated with increased risk of obesity and higher body-mass index, particularly in those with parents who were overweight or obese.

As part of the study, researchers followed a group of 107 children aged two - six from the Early Stockholm Obesity Prevention Project. Each year, their sleep was tracked for seven consecutive days, using a wrist-worn actigraphy. Out of the children, ​43 had parents of low obesity risk, while 64 had parents who were overweight or obese.

While the researchers found a link between late bedtime and obesity risk, other sleep-related issues, including short sleep duration, low sleep efficiency and irregular sleep, didn't significantly increase the risk of gaining more weight. But more research is needed into other potential factors including diet and exercise.

"Late sleep is probably involved in familial vulnerability to obesity development and needs more attention in prevention efforts," the authors conclude.

In a commentary also published in Pediatrics, Nicole Glaser and Dennis Styne, who were not involved in the study note that the research provides some evidence of a causal relation between sleep and obesity because the findings were similar in children not genetically predisposed to obesity.

"In addition," they note, "children were young and of normal weight at enrolment, so obesity-related factors that could interfere with sleep (ie, sleep apnea) were less likely to be present."

That said, Glaser and Styne highlight that the number of children studied was low, and more research is required. "Future studies, using interventions to increase sleep duration and sleep quality, will be needed to address this weighty question," they note.

It's not the first time studies have found a link between later bedtimes and obesity. Research published in Journal of Pediatrics found that pre-school aged children with early weekday bedtimes were half as likely as children with late bedtimes to be obese as adolescents. "Bedtimes are a modifiable routine that may help to prevent obesity," the authors wrote at the time.

According to data from the Australian Institute of Health and Welfare, one in four children and adolescents aged 2–17 were overweight or obese in 2017–18.