For the study, researchers at the University of Otago followed more than 1000 children born in Dunedin between 1972 and 1973.
They found that kids aged between five and 11 who spent less time in bed had higher Body Mass Indexes as adults and were significantly more likely to be obese.
Lead author of the study Erik Landhuis said the importance of getting a good night's sleep was well known, but this was the first study to show potential implications for adult obesity from lack of sleep during childhood.
"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," the Age.com.au quoted Landhuis, as saying.
"It has also been suggested that tired kids may simply have less energy and are therefore less active.
"Our findings indicate that ensuring adequate sleep time in childhood may play an important part in the prevention of adult obesity," Landhuis added.
Researchers documented participants' time in bed every two years between ages five and 11 and measured body weight at age 32.
They ruled out early signs of obesity such as socioeconomic factors, parental control, television watching, and a parental history of obesity as possible explanations for the results.
The study is published in the United States journal Pediatrics.