Lack of sleep a factor in childhood obesity

According to the latest research not getting enough sleep can increase a child's risk of being overweight.

Other studies have suggested that inadequate sleep has a negative effect on a child's social and emotional well-being as well as school performance.

This latest research by a team at Northwestern University, Illinois, has found that a lack of sleep is also a factor in a child being overweight.

The longitudinal study used detailed diaries kept by families to examine children's sleep behaviour and its relationship with weight.

The study involved 2,281 children taking part in a nationally representative survey aged 3 to 12 at the start of the study in 1997.

Follow-up data were collected five years later.

In the diaries the number of hours the children slept was recorded, along with when they went to bed and what time they woke up.

Their height and weight were also logged.

The research team found that children who had less sleep were more likely to be overweight and have higher body mass index measures than those who got more sleep, even when factors such as race, ethnicity and parents' income and educational level were taken into account.

Sleep experts recommend that children ages 5 to 12 sleep for 10 to 11 hours a night and adolescents sleep for 8 to 9 hours, but according to the researchers children in the study at age 7 on average got less than 10 hours of sleep on weekdays and at age 14 got 8.5 hours of sleep on weekdays.

Lead researcher Emily Snell says children who get less sleep tend to weigh more five years later.

Snell and her co-authors Emma K. Adam and Greg J. Duncan say that an extra hour of sleep cut the likelihood of being overweight from 36 percent to 30 percent in children ages 3 to 8, and from 34 to 30 percent in those ages 8 to 13.

Snell says the study suggests that earlier bedtimes, later wake times and later school start times could be an important and relatively low-cost strategy to help reduce childhood weight problems.

The study is published in the journal Child Development.