Losing an hour's sleep doubles the chances of a child or teenager being overweight.
The trend is most pronounced in youngsters who get too little rapid eye movement (REM) sleep - a phase of sleep characterised by side-to-side eye movements that coincides with vividly remembered dreams.
A US study led by Dr Xianchen Liu, from the University of Pittsburgh, monitored the sleeping patterns of 335 children and adolescents over three consecutive nights.
Compared with normal weight children, those who were overweight slept about 22 minutes less per night. They also spent less time in bed asleep, and shorter periods of REM sleep.
After adjusting for other factors, an hour less of total sleep was associated with a two-fold increased chance of being overweight.
One hour less of REM sleep raised the chances of being overweight three-fold.
The scientists wrote in the journal Archives of General Psychiatry: "Although the precise mechanisms are currently under investigation, the association between short sleep duration and being overweight may be attributed to the interaction of behavioural and biological changes as a result of sleep deprivation."
Sleep loss causes changes in hormone levels that may affect hunger, and also provides an individual with more waking hours in which to eat, the authors pointed out.
It also contributed to fatigue, which may result in reduced physical activity the burning up of fewer calories.