London: Kids staying up late at weekends are more likely to be obese, says a new study.
Those who are told to go to bed early on weekend nights get a chance to catch up on the sleep they do not get throughout the week and tend to be thinner.
Researchers at the Chicago University monitored 308 children from four to 10 years of age, measuring the body mass index (BMI) of each and examining their sleep patterns using wrist movement sensors, the journal Paediatrics reports.
The children averaged eight hours per night throughout the week - less than is recommended - with no significant differences between the fatter and thinner children, according to the Telegraph.
However, at weekends, the obese children had shorter and more irregular sleep patterns, the researchers found.
The authors said that obese children were less likely to experience "catch-up" sleep on weekends and the combination of shorter sleep duration and more-variable sleep patterns was associated with adverse metabolic outcomes.
Lack of sleep is believed to lead to increased production of ghrelin, a hormone produced in the gut and the reduced release of a hormone called leptin in fat cells.
Too much ghrelin and too little leptin have been shown to result in a larger appetite.