For adults, getting too much or not enough sleep have both been linked with adiposity and Type 2 diabetes, Xinhua news agency cited the stud as saying.
In children, more sleep has been tied to lower levels of obesity, but research about Type 2 diabetes risk factors has been scarce, according to The Journal of Pediatrics.
To explore possible connections, researchers analysed the body measurements, blood sample results and questionnaire data from 4,525 children of multi-ethnic descent, aged 9-10 years in England.
They found that children who slept longer had lower body weight and lower levels of fat mass.
Sleep duration was "also inversely related to insulin, insulin resistance and blood glucose", they said.
"These findings suggest increasing sleep duration could offer a simple approach to reducing levels of body fat and Type 2 diabetes risk from early life," professor Christopher Owen, who led the research at St George's, University of London, said in a statement.
"Potential benefits associated with increased sleep in childhood may have implications for health in adulthood," Owen said.
The researchers did not find an association between sleep duration and cardiovascular risk factors, including blood lipids and blood pressure.
This lack suggests "sleep duration does not alter other cardiovascular risk in early life, other than by increased obesity and metabolic risks which, if sustained or accentuated, take time to accelerate cardiovascular risks", the researchers wrote.