A lack of sleep during childhood may be the cause of adult weight gain.

A study conducted by New Zealand’s University of Otago says children who do not get enough sleep each night during childhood face a greater risk of obesity as they mature.

The study involved more than 1000 children born in New Zealand between 1972 and 1973, who were monitored until they were 32 years old. The children’s parents kept careful records of the kids’ bedtimes at ages 5, 7, 9 and 11 years. Researchers then used these numbers to estimate the amount of sleep the children were getting each night as they grew up.

When the study concluded in 2005, the experts crunched together the sleep statistics with the Body Mass Index – or BMI – numbers of the now-adult study subjects. Then, they averaged in or factored out important familial and lifestyle predictors of adult BMI, such as inherited build, physical activity, television viewing, and smoking.
The results were eye-opening: The kids who had shorter sleep times had significantly HIGHER adult BMI values as adults.

Although the researchers could not find a mechanism among the data for the association between short sleep time and the raised risk of obesity, some believe that elevated levels of ghrelin [GREH-lin], an appetite-related hormone, and decreased levels of leptin, which is a natural appetite depressant produced by the body, may be responsible.

Shorter sleep times may also reduce a child’s physical activity levels and alter their dietary habits, causing them to crave more high-calorie foods to compensate for their low energy levels. In other words, a kid who is tired from lack of sleep is more likely than not to grab a Twinkie for a quick sugar rush!

The doctors involved in the study say that more research on the connection between lack of sleep and obesity needs to be done. Until the causes of weight gain are clearer, however, they say it’s up to parents and caregivers to make sure that children get plenty of restful sleep.