Overweight or obese children tend to sleep less, a study has found.
The study claimed "sleep deficit" among school-going kids would hinder their performance at school right through the week.
Professor Tim Olds, who studied the sleep patterns of more than 4000 children from across the country, said poor sleep was known to lead to memory recall problems and impair cognition.
Many children in his study were "sleep deprived for up to two to three hours" overall from Monday through to Friday, and this had ramifications not only on their education he said.
"Kids who are overweight and obese sleep less," the Herald Sun quoted Professor Olds, from the University of South Australia, as saying.
"And it's probably because they sleep less they have a predisposition to being overweight, and not the other way around," he added.
Olds said weight gain could be the result of these children being less active overall, as they often also had more "screen time" spent watching television or using a computer or games console.
A routine of poor sleep could also cause hormonal changes that would promote weight gain, he added.
"It may be hormonal disruption. We know that short sleep can increase the hormones which make you very hungry and decrease the hormones which make you feel satisfied," said Olds.
The results of the study have been published in the Australian and New Zealand Journal of Public Health.