Sleep loss can affect gene expression

This article got some press, so I thought I would comment on it. Researchers took 26 healthy people, and allowed them six or less hours of sleep per night for a week. They then kept them up for 40 hours straight and then let them sleep as much as they want, up to 10 hours per night for another week. I can only see the abstract, so some of the details are unknown. From blood samples, researchers determined that 711 different genes were altered during the sleep deprivation period. The blood samples were taken 3 hours apart as the participants stayed up for 40 hours straight. It's not clear why they did this - it could alter the results. The genes that were affected play a part in metabolism and our internal body clock. However, some of the genes affected have no known function. From the abstract, it's not clear that the genes were altered by the week of deprivation or the 40 hour total sleep loss.