People who do not get enough sleep may be more likely to choose bigger portions of energy-dense foods, increasing their risk of putting on weight, a new study suggests.

In a previous study, Swedish scientists found that activation of the part of the brain that controls the desire to eat was increased in young men who missed out on an entire night's sleep.

They decided to investigate this further by studying whether sleep deprived people choose different types of foods and bigger portions.

They looked at a small group of men, all of whom were considered a healthy weight.

The men attended a buffet and a number of scenarios were studied. The men were asked to choose their ideal portion sizes for seven meals and six snacks. They did this when they were feeling full and also when they were hungry.

However they also did it after a night of sleep deprivation and after a night where they had obtained around eight hours of sleep.

"After a night of total sleep loss, these males chose greater portion sizes of the energy-dense foods. Interestingly, they did so both before and after a breakfast, suggesting that sleep deprivation enhances food intake regardless of satiety (feeling full)," the scientists from Uppsala University explained.

They said that as a result, sleeping habits may affect weight gain.

"Bearing in mind that insufficient sleep is a growing problem in modern society, our results may explain why poor sleep habits can affect people's risk to gain weight in the long run."

Details of these findings are published in the journal, Psychoneuroendocrinology.