Researchers at Uppsala University have demonstrated that one night of sleep loss has a tissue-specific impact on the regulation of gene expression and metabolism in humans. This may explain how shift work and chronic sleep loss impairs our metabolism and adversely affects our body composition. In the new study the researchers studied 15 healthy normal-weight individuals who participated in two in-lab sessions in which activity and meal patterns were highly standardised. In randomised order the participants slept a normal night of sleep (over eight hours) during one session and were instead kept awake the entire night during the other session.