Getting enough sleep as a child may be one of the keys to fighting off obesity.
Researchers from Mass General Hospital followed more than a thousand children from infancy to age seven.
The children were recommended to get anywhere from nine to 12 hours of sleep, depending on age.
The study found that those who consistently got less than that were more likely to be obese at age 7.
Researchers say more studies are needed, but sleep does affect hormones and metabolism.