Sleep deprivation causes metabolism to drag, according to new research. This results in the body using less energy, according to a new study released in the American Journal of Clinical Nutrition this week. Christian Benedict of Uppsala University in Sweden, who led the study, said that sleep loss often results in distinct weight gain and not because of hunger pangs alone; he argued that less sleep will slow the rate at which calories are burned. Dr Benedict, alongside colleagues, put 14 male students through a series of sleep situations - shortened sleep, no sleep and normal sleep - over several days before measuring changes in how much they ate, their blood sugars, hormone levels and metabolic indicators. Even just one night of missed rest slowed metabolism and reduced energy expenditure for breathing and digestion by between five and 20 per cent. The expert concluded: "Our findings show that one night of sleep deprivation acutely reduces energy expenditure in healthy men, which suggests sleep contributes to the acute regulation of daytime energy expenditure in humans."