A new study has linked a later bedtime with an increased risk of obesity for kids - although the researchers say parents shouldn't rush to put their preschoolers to sleep earlier as a result.
Instead, concerned moms and dads should focus on maintaining a regular routine when it comes to scheduling meal and bed times, said Dr. Claude Marcus, a professor of pediatrics at the Karolinska Institute in Sweden and an author of the study, which published Tuesday in the journal Pediatrics.
The research, which was part of a wider study on obesity, focused on 107 children in Sweden, with 64 of the children having a parent who classified as overweight or obese.
The researchers monitored each child's weight, height and waist circumference from ages one to six; all of the children had similar measurements when the study started. Sleep was measured for seven consecutive days once a year for the length of the study by using a tracker worn on the child's wrist.
They found that children who habitually went to sleep late - defined by the researchers as past 9 p.m. - had a wider waist and higher BMI (body mass index) by the end of the study.
Marcus suggested that staying up beyond 9 p.m. could be one sign of an overall lifestyle that puts kids at greater risk of being overweight, rather than their weight gain being directly connected to their bedtime.
Previous research has found that a shorter sleep duration is linked to an increased risk of obesity in childhood. However, the study from Marcus' team found that no matter how long a child slept, going to bed after 9 p.m. was associated with an increased of obesity and a higher BMI, CNN reported.
In adults, Marcus said that irregular sleep and less sleep have been associated with a greater risk of obesity, with some suggestion that people who sleep less eat more.
"The causality is difficult to establish. It could also be an effect of stress, rather than sleep," Marcus said.
