A new study finds that catch-up sleep on the weekend puts people at risk of gaining weight.

The study, published Thursday in the journal Current Biology, showed that people who did not sleep enough during the week but caught extra hours on the weekend tended to snack more and have an increased risk of diabetes.

“Our findings suggest that the common behavior of burning the candle during the week and trying to make up for it on the weekend is not an effective health strategy,” said the paper's senior author, Kenneth Wright, director of the Sleep and Chronobiology Lab at the University of Colorado Boulder.

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The researchers looked at the sleeping habits of 36 healthy adults aged 18 to 39 over 10 days in a lab. They were divided into three groups: those who slept nine hours a night for nine consecutive days, those who had their sleep restricted to only five hours a night for nine nights, and those who slept no more than five hours a night for five days followed by a weekend when they could sleep as much as they liked, before returning to restricted sleep for two days.

Both sleep-deprived groups snacked more at night, resulting in weight gain, and saw declines in insulin sensitivity, a warning sign for diabetes. The weekend recovery group experienced some mild improvement during the weekend, but those benefits were negated when they resumed their weekday sleep-restricted schedule.

The phenomenon that Wright discusses is called social jetlag. It occurs when one’s sleep-wake cycle, otherwise known as circadian rhythm, is disrupted, and it’s associated with long-term negative health outcomes, including obesity.

“We have these hormones called leptin and ghrelin,” said Azizi Seixas, a sleep expert and assistant professor at the New York University School of Medicine, who was not involved in the study. “One is associated with satiety, and the other one increases your appetite. They both go out of whack when you’re sleep deprived.”

He added, “Sleep deprivation causes people to have poor impulse control, and they’re more likely to consume empty calorie foods like soda and high starch foods.”

The group that had their sleep restricted the entire time also experienced a 13 percent decline in their insulin sensitivity. The weekend recovery group had more variable declines in their insulin sensitivity, ranging from 9 to 27 percent.

“I think people feel that they can be machines during the week and then become human on the weekends. Sleep isn’t a math game, you can’t balance it out. Your body needs a schedule for a reason. This demonstrates the importance of having a regular sleep schedule,” Seixas said.

The American Academy of Sleep Medicine recommends seven or more hours of sleep per night for adults.

Recent studies have also highlighted the importance of sleep quality, as interrupted sleep has been shown to cause a decrease in focus and attention, weakening of the immune system and cognitive slowing.

“Sleep is not trivial,” Seixas said. “It’s the time when the body does most of its repair work. That work needs to be done during the week as well as during the weekend.”