Research on more than 2,500 children aged 16 months found that those who got less sleep ate a 10th more calories than others who slept for longer.
Researcher Dr Abi Fisher, from the UCL Health Behaviour Research Centre, said: "We know shorter sleep in early life increases the risk of obesity so we wanted to understand whether shorter sleeping children consume more calories.
"Previous studies in adults and older children have shown sleep loss causes people to eat more but in early life parents make most of the decisions about when and how much their children eat - so young children cannot be assumed to show the same patterns."
The study published in the International Journal of Obesity found that those who slept for less than 10 hours consumed on average 105kcal more daily than peers sleeping over 13 hours.
Researchers said the extra calories in their early years put children at risk of obesity and related health problems later in life.
The study by University College London (UCL) examined 1,300 sets of twins, monitoring their sleep aged 16 months. They found those who slept for less than 10 hours consumed an average of 1,087 calories, while those with more sleep had an average 982 calories.
Researchers said the reason for the difference was not clear, but suggested that regulation of appetite hormones may become disrupted by shorter sleeping patterns.
Dr Fisher said more research was needed to establish why it was that children who slept less ate more, but said parents should be aware of the increased risk of obesity if children slept less.