Only one in 10 of the children with the earliest bedtime grew into obesity
Society often tries to solve problems after the fact. So parents force their obese teenager to eat cabbage and carrots for supper, before planning ambitious hiking weekends to get them out and about. But the damage is already done. And the acne-laden teenagers end up making up for lost time by sitting in a hidden corner at the local fast food joint with a plate of fatty food.
Parents should rather look at the patterns they introduce to their children earlier in life. Researchers at the Ohio State University College of Public Health say the key to obesity in teenagers is the time that they go to bed in their formative years. To be precise, children who go to bed before 8pm are half as likely to become obese than those that regularly go to bed after 9pm.
“For parents, this reinforces the importance of establishing a bedtime routine,” wrote lead author Sarah Anderson, an associate professor of epidemiology.
The researchers – publishing in the Journal of Pediatrics last week – collated data on 977 children. They were part of the university’s Study of Early Child Care and Youth Development, which followed babies in 10 locations from 1991.
The weight of those children was then tested at age 15.
Anderson and her team divided the teenagers into three categories: those that had regularly gone to sleep before 8pm, those that had gone to bed between 8pm and 9pm, and those that regularly slept after 9pm.
Only one in 10 of the children with the earliest bedtime grew into obesity, while 16% of those going to sleep slightly later became obese. But 23% of those that regularly went to bed after 9pm were obese by age 15.
The research said this was clear evidence that sending children to bed earlier had a positive impact on their health.
“It’s something concrete that families can do to lower their child’s risk, and it’s also likely to have positive benefits on behaviour and on social, emotional and cognitive development,” said Anderson.
The team also videotaped interactions between the children and their mothers during childhood. This was to ensure no other factors might have influenced the children to gain weight.
This found that children who went to bed latest – and had the least interaction with their mothers – ended up being the most obese. They also found that later bedtimes were common in non-white children, whose mothers had less education and lived in lower-income households.
For children who ended up obese as teenagers, it became increasingly harder to lose that weight, according to the research. This meant they were locked into a lifetime of poor health, with issues such as diabetes and heart disease shortening their lifespan.
Other research has shown that children are biologically predisposed to fall asleep before 9pm. But the team said that this was often difficult in families where the parents arrived home late, and had to rise early to go to work.
In these circumstances, creating a consistent bedtime routine makes it easier for children to get used to falling asleep at the same time. Anderson also wrote in the research that looking at the sleeping times in children would also give the rest of a family a chance to adjust their own sleeping times and patterns. This could improve the health of the whole family.
The research, however, doesn’t mean that getting a child to sleep early is all a parent needs to do. The team said they had not looked at the other factors that contribute to weight gain in childhood. Their research solely looked at how sleep times affect weight.
So sleep – and cabbage, and long walks – are all important to ensure the health of a child.