Early pre-school bedtimes cut risk of obesity in later life

07 August 2016

Preschoolers who are regularly tucked into bed by 8 p.m. are far less likely to become obese teenagers, new research has found.

Bedtimes after 9 p.m. appeared to double the likelihood of obesity later in life, according to a study from The Ohio State University College of Public Health.

Lead author and associate professor in epidemiology, Sarah Anderson, says the study reinforces the importance of establishing a bedtime routine.

“This is 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,” she says.

It also arms Plunket nurses, GPs and paediatricians with scientifically-based advice for parents.

The new research, published in the TheJournal of Pediatrics, used data from 977 children who were part of the Study of Early Child Care and Youth Development.

Anderson and her co-authors divided preschool bedtimes into three categories: 8 p.m. or earlier, between 8 p.m. and 9 p.m. and after 9 p.m. The children were about 4 ½ years old when their mothers reported their typical weekday bedtime.

The researchers linked preschoolers’ bedtimes to obesity when the kids were teens, at an average age of 15.

They found a striking difference: Only 1 in 10 of the children with the earliest bedtimes were obese teens, compared to 16 percent of children with mid-range bedtimes and 23 percent of those who went to bed latest.

Half the kids in the study fell into the middle category. A quarter had early bedtimes and another quarter went to bed late.

Because the emotional climate at home can influence routines such as bedtime, Anderson and her colleagues also examined interactions between mothers and their children during a videotaped playtime. Scientists call the measurement “maternal sensitivity” and it factors in maternal support, respect for the child’s autonomy and lack of hostility.

Regardless of the quality of the maternal-child relationship, there was a strong link between bedtimes and obesity, the researchers found. But the children who went to bed latest and whose moms had the lowest sensitivity scores faced the highest obesity risk.

The researchers also found that later bedtimes were more common in children who were not white, whose mothers had less education and who lived in lower-income households.

Previous research has established a relationship between short sleep duration and obesity. One study found a correlation between late bedtimes and obesity risk five years later.

This new bedtime study is the first to use data on obesity collected about a decade after the children were in preschool.

Putting a child to bed early doesn’t guarantee he or she will fall immediately into a deep sleep, but establishing a consistent bedtime routine makes it more likely that children will get the amount of sleep they need to be at their best, Dr Anderson says.

“It’s important to recognize that having an early bedtime may be more challenging for some families than for others. Families have many competing demands and there are trade-offs that get made. For example, if you work late, that can push bedtimes later in the evening.”

However, previous research shows that the majority of young children are biologically pre-programmed to be ready to fall asleep well before 9 p.m.

The study doesn’t answer questions about how sleep time intertwines with a variety of other factors that can contribute to weight gain in childhood, including physical activity and nutrition.  This remains an active area of research.