The study followed more than 1000 children born in Dunedin between 1972 and 1973. The latest research shows that children who spent less time in bed between ages 5 and 11 years had higher Body Mass Indexes (BMIs) as adults and were significantly more likely to be obese.
The paper appeared in the US journal Pediatrics
on 3 November 2008.
The researchers were able to rule out early signs of obesity, socio-economic factors, parental control, television watching, and a parental history of obesity as possible explanations for the results. Time in bed was documented every two years between ages 5 and 11 and body weight was measured at age 32.
Lead author Erik Landhuis says worldwide trends show a significant reduction in children's sleep times over the last 30 years. For instance, one study showed that children are going to bed two hours later than they were 20 years ago.
"This decrease in average sleep duration has coincided with increasing rates of adult obesity. Our findings indicate that ensuring adequate sleep time in childhood may play an important part in the prevention of adult obesity," says Mr Landhuis.
Although the importance of getting a good night's sleep in both children and adults is well known, this is the first study to show that the effects of short sleep time during childhood may have long lasting implications for adult obesity, he says.
"It is not clear why lack of sleep might lead to weight gain, but experimental studies have shown that sleep deprivation may disrupt the hormones that regulate appetite. It has also been suggested that tired kids may simply have less energy and are therefore less active."
The study, entitled Childhood sleep time and long-term risk for obesity: 32-year, prospective, birth cohort study
was authored by Erik Landhuis, Professor Richie Poulton, Dr David Welch and Associate Professor Bob Hancox.
The study was funded by the Health Research Council of New Zealand and supported by the US National Institute of Mental Health.