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If you’re not getting enough sleep during the week, new research suggests that you can’t make up for it on the weekends.

The small study, published in the journal Current Biology, found that people who slept too little during the week and tried to catch up on the weekend actually ended up slightly unhealthier than those who just consistently slept too little.

More on Sleep

For optimal health, adults are supposed to sleep about 7 to 9 hours each night. But many people don’t meet those recommendations.

According a growing body of research, this widespread sleep deprivation puts people at an increased risk of weight gain and a range of chronic illnesses, including diabetes. That’s in part because insufficient sleep can alter your metabolism.

The new study can’t draw any sweeping new conclusions because it followed only a small group of people for a short period of time. But it's one of the first looks at how changing a sleep schedule between the week and the weekend might contribute to those metabolic changes above and beyond the ill effects of sleep deprivation in general.

“In modern society, most people get insufficient sleep during the standard work week and then they attempt to catch up or get more sleep on the weekend,” says the study's author, Christopher Depner, Ph.D., an assistant research professor in the sleep and chronobiology laboratory at the University of Colorado Boulder. “It’s a continual cycle.”  

What the Study Found

The study compared three groups of participants. For two nights, they all got similar amounts of sleep, going to bed around 11 p.m. and waking up around 8 a.m. Then, for the next nine nights, the three groups had different sleep schedules.

A control group of eight participants continued to sleep 9 hours each night. A sleep-restriction group of 14 participants slept 5 hours each night.

And a weekend recovery group of 14 participants simulated the sleep schedule of someone trying to catch up on sleep on the weekend. They slept 5 hours each night for five nights, followed by two nights when they could sleep as much as they wanted, and then two nights when they slept for 5 hours again, as if they were returning to work.

On their "weekend days," they could go to bed when they wanted, wake up when they wanted, and even take naps. This led to an average of 9 hours each night, generally with a later bedtime and wake-up time than they’d been assigned at the beginning of the study.

The researchers also measured food intake, weight, sleep duration, and metabolism in all three groups.

By simulating a typical week of sleep, the study offers a unique look at the effects of sleep schedules and sleep restriction, says Jeanne Duffy, Ph.D., a neuroscientist in the division of sleep and circadian disorders at Brigham and Women's Hospital in Boston. Very few studies have used that approach, she says.

The results provided a few interesting findings. First, the group that slept in on the weekend and the sleep-restriction group gained weight over the course of the study. “Recovery sleep did not prevent weight gain associated with insufficient sleep,” Depner says.

Both groups also had reduced insulin sensitivity. That alters the body’s ability to process sugar and can lead to diabetes or other health problems if it continues over a long period of time. The weekend recovery group actually had even lower insulin sensitivity in their liver and in their muscles than the sleep-restriction group.

“That was unexpected,” Depner says. “We have a hint that there are potentially negative health consequences of this continuous cycling back and forth.”

Staying up later on the weekend than during the week can affect your internal clock and subsequently your metabolism, which might help explain the negative effects found in the weekend recovery group. 

“That effect could very well be why we don’t see benefits from weekend sleep, and it could very well be why we see negative effects,” Depner says. 

What You Should Do

“The issue we tried to study is really a product of modern society," Depner says. We generally work Monday to Friday, and then have two days without work—where we might be tempted to catch up on sleep.

It would be "a big ask to change the way society operates," he says.

But there might be ways to minimize the negative effects of insufficient sleep without relying on a weekend catch-up, which this research shows isn’t effective.

The study findings confirm that a regular sleep schedule is important. “It reinforces that the best thing to do is allow yourself to sleep at the same time every night of the week,” Duffy says.

In addition, avoiding late-night snacking might help reduce some of the negative metabolic effects of insufficient or delayed sleep.

“A healthy diet is not only healthy foods, but also a healthy time to eat foods,” Depner says. “If you know you’re not getting enough sleep, you should avoid food intake late at night.”

Those strategies, though, might be useful only for short periods of insufficient sleep, Duffy says. “If you have a crazy week, you might be able to do [those] things to lessen the impact of sleep restriction," he says. "But if you do that every week, month after month, there may be nothing we can do to combat that.”

The new study reinforces the importance of sleep in a healthy lifestyle, Depner says. “Getting enough sleep and on a consistent schedule is, I would say, at least as important as physical activity and nutrition.”