Children under six years old were more likely to be obese if they had a bedtime after 9pm, according to a study published on Feb. 18, 2020 in Pediatrics.
The study followed 107 children in Sweden from ages two to six and established sleep patterns using wrist trackers rather than often unreliable self-reporting by the kids and parents.
Children who went to bed late and who had obese parents gained an average of 3.45 centimeters (1.36 inches) in waist circumference, compared to a gain of 0.91 centimeters (0.35 inches) in children who went to bed late and had parents who were not obese. Children with obese parents who went to bed early gained an average of 1.64 centimeters (0.65 inches) in waist circumference.
The link between childhood and parental obesity raises concerns as adult levels of obesity continue to increase; 39.6% of the adult US population was obese in 2018. The study noted that adolescents and adults with later bedtimes tend to eat more fast food and fewer vegetables, in addition to reporting more screen time and more late-night calorie intake.
Study author Dr. Claude Marcus, Professor of Pediatrics at Karolinska Institute, stated, “This late bedtime was one factor that really stood out. It was associated with increased weight. However, what we can see is [only] an association. If you put your kids to bed earlier, would it change anything? That’s something we don’t know… My personal hypothesis is that this is more of a marker of a more irregular life.”
Dr. Marcus suggested maintaining a regular routine for meal and bed times to counteract the obesity risk because inadequate or irregular sleep could be the cause of obesity, as could kids eating more snacks late at night.
The suggestion takes into account the cultural variations in children’s bedtimes globally. Kids in Australia typically go to bed at 7:28pm, while kids in the US go to sleep at 8:52pm, kids in Singapore are up until 9:38pm, and kids in Hong Kong don’t go to sleep until 10:17pm. Researchers concluded that getting kids to bed earlier should be addressed as part of obesity prevention efforts.
