Ananova:

Children can stay slim by having a full night's sleep.

Scientists at Pittsburgh University discovered that just one hour less sleep could mean a child would be twice as fat.

Researchers monitored the sleep patterns of 335 kids aged seven to 17, reports The Sun.

Dr Xianchen Liu, who led the study said it was due to "biological changes as a result of sleep deprivation".

Larger children slept for an average 22 minutes less than normal weight kids. They also had shorter REM sleep.

They also discovered that sleep loss changes hormone levels and affects hunger giving more time in the day to eat.