Researchers in New Zealand have linked a lack of sleep among young children to obesity.
Documented in the British Medical Journal (BMJ), the report underlined that young children who do not get enough sleep have a higher chance of becoming overweight by the age of seven.
This could happen even if the child exercises on a regular basis and follows a healthy diet.
The study involved a total of 244 children. Factors such as weight, height and body mass index (BMI) were considered by the experts.
A gadget that measures body movement was also used to analyse how much the participants slept and their levels of physical activity.
All these factors were measured every six months from age three to seven. Their dietary intake was assessed with the help of questionnaires.
Other determinants, such as birth weight, mothers' education, income, maternal BMI, smoking during pregnancy and ethnicity were also recorded because they have been shown to influence a child's weight.
The researchers found that, on average, children slept 11 hours per day at all three ages.
But those children who slept an extra hour per night at ages three to seven had a reduction in BMI of 0.48 and a 61% reduced risk of being overweight when they were seven.
In a child of average height, this corresponds to a difference of 0.7kg body weight, they said.
"Good sleep hygiene should include regular bedtime and wake up time and no visually stimulating items in bedroom like TVs and games consoles. This should be established long before treatments like star charts or melatonin are considered. Children lacking sleep regulation may also lack hunger/satiation regulation, so a tendency towards obesity is possible" - Mark Wheeler, Nottinghamshire