In a recent study, Buxton showed that people like shift workers who have to sleep on short, disrupted schedules burned fewer calories at rest. He estimated that the drop in metabolism could lead to a gain of 10 to 12 pounds in a year's time.
So how can you counter the effects of social jet lag? It's not so easy. When asked, Roenneberg said trying to keep your work schedule on weekends might not really help because people keep those kinds of abnormal schedules (getting up at 6 a.m.) because they have to, not because they really want to. Trying to keep the same disrupted schedule on the weekend would just add to a person's sleep debt, which isn't a great solution.
"The consequences of sleep debt are enormous," he says.
In a perfect world, Roenneberg says, society's whole attitude toward sleep would change. For example, work schedules would be more aligned with the biological clock and start later so that people could go to sleep later. Sleep, he thinks, should get more respect.
Still, daylight may help, Roenneberg says. Early risers who feel like they need help falling asleep earlier at night -- so that they can get more sleep -- may be helped by getting more sunlight in the morning and avoiding sunlight in the afternoon and evening.
People who would like to stay up a little later should try to get more sunlight in the afternoon and evening, he says.