During the two-night study, they gave the participants one night to adapt to their new environment before they began their night of sleep deprivation. On the second night, they randomized the participants into two groups; one group stayed up all night and the other, acting as the control, got a normal night of sleep. After each night, researchers took blood samples as well as fat tissue samples from the abdomen. They found extreme changes in the genes of the deprived subject’s metabolism--specifically, they found impaired glucose tolerance. “This is pretty exciting that all of this happened after one night of sleep loss,” says Cedernaes.