Going to bed later than usual when there is no school the next day can take its toll on children in terms of being overweight. According to a study carried out by researchers at the University of Helsinki, children who go to bed later on weekends have a higher body mass index and a greater waist circumference than those who go to bed at the same time whether or not in school day.
Previous studies had already established a correlation between the duration of sleep and being overweight, but the Finnish study focuses not on the time spent sleeping but on the regularity or irregularity of going to bed.
After examining data from 10,245 children, the authors of the report (published in the Journal of Sleep Research ) say that children who went to bed two hours later over the weekend had, on average, 2.4 centimeters more waist (in children 148 centimeters tall) than those who maintained regular sleep routines.
They also found that they had a higher body mass index, and both associations were independent of other lifestyle factors, including screen time or sleep.
“Irregular sleep schedules, especially on non-school days, are associated with increased adiposity,” the Finnish doctors say in the conclusions of their study. And they emphasize that this increase in abdominal fat is not reversed over time, but was maintained during the two and a half years that they followed up.
“The results of our work suggest that children may gain more weight if the time they go to bed changes too much,” they warn.
And they suggest that going to bed early on weekends should perhaps be promoted as one more obesity prevention measure among school-age children.
Experts believe that going to bed later and waking up later alters your internal biological clock (they call it social jet lag), and this can affect how efficiently food is processed. That is why they believe that parents should pay more attention to maintaining a regular schedule and routine on weekends.
On the other hand, the study by experts from the Folkhälsan Research Center found that children who spent more time in front of the computer screen tended to delay bedtime more on weekends.
