March 1, 2019
Wake up, America! A study conducted at the University of Colorado–Boulder has found that trying to catch up on shut-eye over the weekend may not be such a good idea—for either your waistline or your health, CNN reported on February 28.
“Weekend catch-up sleep is not protective,” Dr. Vsevolod Polotsky, director of Sleep Research at the Johns Hopkins University School of Medicine, told the cable news network, adding, “The bottom line of this study is that even if you sleep longer on weekends, if you continue to sleep poorly, you will still eat too much, and you will still gain weight.”
Study author Kenneth Wright, Jr., who directs the Sleep Lab at the UC-Boulder, agrees. “Sleeping in on weekend doesn’t correct the body’s inability to regulate blood sugar, if that weekend is followed by a workweek or [a]school week full of insufficient sleep,” he told CNN.
The study by Wright and his colleagues—published in the journal Current Biology—assigned 36 healthy young men and women to three groups that prescribed different sleep requirements over a total of 10 days. None of the participants had newborns in the home or any health impairments that would affect the quality of their sleep.
The first group had the opportunity to sleep for nine hours each night for the 10 days. The second group was restricted to only five hours of sleep a night for the same duration, while the third was restricted to five hours Monday through Friday but allowed to sleep as long as they wanted on the weekend and go to bed as early as they liked on Sunday night. Come Monday, that third group was put back on the deprived sleep schedule of only five hours a night.
Both of the sleep-deprived groups snacked more after dinner and gained weight during the study—men, much more than women, CNN reports. The sleep-deprived men showed an overall 2.8% increase in their weight, while women’s body size went up by only 1.1%. By comparison, men who slept in on the weekend showed a 3% increase in weight, while women’s body size went up 0.05%
Gaining weight while sleep-deprived isn’t surprising, Wright said. “One of the things we and others have found in the past is that when people don’t sleep enough, they tend to eat more, partly because their body is burning more calories. But what happens is that people eat more than they need and therefore gain weight.”
That could be in part, Polotsky told the news outlet, because hunger hormones are affected by a chronic lack of sleep. “The hormone leptin decreases appetite, while the hormone ghrelin increases appetite,” explained Polotsky, who was not involved in the study. “We know from previous research that sleep deprivation causes leptin to drop and ghrelin to rise, so you’re hungry.”
What was surprising to the researchers is what happened to the group who slept in on the weekends. “Even though people slept as much as they could, it was insufficient,” Wright said. “As soon as they went back to the short sleep schedules on Monday, their ability of their body to regulate blood sugar was impaired.”
Why? One of the reasons the weekend group may have been more affected is because their circadian rhythm, or biological clock, had been altered, depriving the body of certain hormones.
“If you catch up during weekends, you habitually eat later, because the circadian clock is shifting,” Polotsky said. “Add in after-dinner snacks; the sleep-deprived eat much more after dinner, as well.”
Not only that, but the weekend recovery group showed increased sensitivity to insulin in both their muscles and their livers, a result not found in the second group on restricted sleep. That’s important, Wright explained to CNN, because the muscle and liver are two of the most important tissues that take up blood sugar after eating.
“That helps us understand why is it that when we don’t get enough sleep, we have an increased risk for things like diabetes,” he added, because “short, insufficient sleep schedules will lead to an inability to regulate blood sugar and increases the risk of metabolic disease in the long term.”
Metabolic syndrome is an array of symptoms such as fat around the waist, abnormal cholesterol, high blood sugar, and high blood pressure—all of which can raise the risk of heart disease, stroke and diabetes.
“And when we go back to getting too little sleep again,” Wright told CNN, “we’re doing things that could be negative for our health long-term.”
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