Children under the age of five who don¡¯t get enough sleep at night are more likely to become fat at a young age, according to a recent study in the U.S.

¡±We found a strong relationship between hours of nighttime sleep in early life and obesity measured at five to nine years,¡± wrote the authors of the study.

The study found that nearly one in five American children is overweight (17 percent). Getting enough sleep at night could play a key role in preventing obesity.

Taking a nap during the daytime seemed to have no effect on the children¡¯s weight.

Also getting little sleep at night did not affect the weight of the older children over nine years old.

The exact reason for this study is not known. But the authors of the study said that getting less sleep could lead to decreased physical activity due to tiredness and increased calorie intake.