Sleeping in late on the weekends won’t protect you from the ravages of barely sleeping during the work week, suggests a new study. While extra weekend sleeping did temporarily help volunteers eat lighter and better control their blood sugar, the health benefits went away as soon as they started not sleeping much again. In some ways, they were even worse off than people who consistently slept poorly.
Getting a few extra hours of shut-eye on the weekend to pay off sleep debt accumulated during the week has long been a strategy for any typical university student or shift worker. But according to the authors behind this study, published Thursday in Current Biology, there’s been surprisingly little research as to how sleeping in affects health.
So the researchers, based at the University of Colorado in the US, conducted a relatively simple experiment.
They recruited 36 healthy young volunteers, split evenly by gender, to stay at their sleep lab for two weeks. After taking three days to establish a baseline of typical sleep, the volunteers were split into three groups. One group was the control, sleeping around eight to nine hours a night for nine days, while one group was only allowed to sleep around five hours a night. The last group slept poorly for a 5-day workweek, then had the chance to sleep as long as they wanted on the weekend, and then had to sleep poorly again for two more days.
As expected, compared to the control group, the chronically bad sleepers snacked more after dinner and had reduced insulin sensitivity—a risk factor for metabolic conditions like high blood sugar, type 2 diabetes, and obesity. Over the weekend, the late sleepers got about an extra hour of sleep a night (They slept more on Friday and Saturday, but didn’t get to bed earlier on Sunday, despite knowing they would be woken up early on Monday). That extra sleep seemed to help them to eat less after dinner on average.
Importantly, though, once this group went back to their short sleep schedule, their level of midnight snacking, weight gain, and lowered insulin sensitivity fell in line with the chronically bad sleep group; there were even signs their health became worse. After sleeping poorly again, for instance, the circadian body clock of weekend sleepers was delayed, while insulin sensitivity in their muscles and liver was higher on average than that of the chronically poor sleep group.
Thankfully, the tired volunteers in both groups did have a few days after the experiment to sleep extra long. But it’s unclear, given that volunteers only slept an extra hour on weekends when they were free to sleep in, just how much weekend sleeping will help the typical sleep-deprived person.
“The key take-home message from this study is that ad libitum weekend recovery or catch-up sleep does not appear to be an effective countermeasure strategy to reverse sleep-loss-induced disruptions of metabolism,” Kenneth Wright, a sleep scientists at the University of Colorado Boulder, said in a statement.
While it’s possible that people who only sometimes lag behind in sleep during the week could still benefit from sleeping in on weekends, that doesn’t describe a substantial chunk of people in Britain. Other research has found that over a third of Brits don’t get a recommended seven hours of sleep a night—many of whom presumably try to catch up on sleep in their free time. It’s also the latest study to find a clear link between poor sleep and poor metabolism.
So yeah, just some lovely news to chew on while you head off for the weekend. Sleep tight!
Featured image: Oli Scarff (Getty Images)