Sleeping in Doesn’t Mitigate Metabolic Changes Linked to Sleep Deficit

Rita Rubin, MA

JAMA. Published online May 15, 2019. doi:10.1001/jama.2019.4701

One of the first studies to suggest that insufficient sleep can disrupt metabolism came out 2 decades ago. And yet, despite growing evidence that inadequate slumber is a risk factor for obesity and diabetes, approximately a third of US adults sleep fewer than the 7 hours a night recommended by the American Academy of Sleep Medicine and the Sleep Research Society. Many people think they can repay sleep debt incurred during the week by catching extra z’s on the weekend. But, unfortunately, it’s not that easy to mitigate the metabolic dysregulation associated with recurrent insufficient sleep, suggests a recent study in Current Biology.Sleepless in the Sleep Lab

The researchers brought 36 healthy normal-weight adults, aged 18 to 39 years, into their sleep lab and randomly assigned them to 1 of 3 groups:

• Sufficient sleep (control group), consisting of up to 9 hours of sleep per night for 9 nights.
• Sleep restriction without weekend recovery sleep, consisting of up to 5 hours of sleep per night for 9 nights.
• Sleep restriction with weekend recovery sleep, consisting of up to 5 hours of sleep per weeknight, unrestricted sleep on the weekend, followed by another 2 weeknights of sleep restriction.

Prior to randomization, baseline sleep was assessed in the lab over 3 nights; participants slept on average about 8 hours each night. Over the next 9 days, beginning on a Monday, participants slept restricted or sufficient hours, depending on their group assignment, and the scientists assessed their eating patterns, weight gain, and changes in insulin sensitivity.

Those assigned to sleep restriction with weekend sleep recovery slept a total of only 3 extra hours Friday and Saturday night, even though they had missed out on more than 12 hours of sleep the previous 5 nights. On top of that, sleeping in on the weekend disrupted their circadian clock, making it difficult for them to fall asleep Sunday night, even though they had to awake early Monday morning.

Late-Night Munchies

Sleep restriction was associated with rapid diet and metabolic changes:

• Insulin sensitivity declined within only 3 days of sleep restriction.
• The decline in insulin sensitivity was more pronounced among participants allowed weekend recovery sleep. By the end of the study, insulin sensitivity decreased about 13% among those not allowed recovery sleep but fell as much as 27% among those allowed weekend recovery sleep.
• Participants not allowed weekend recovery sleep consumed an excess of around 500 calories each night after dinner compared with baseline calorie intake.
• Participants allowed weekend recovery sleep consumed as much as 641 calories more after dinner on weeknights relative to baseline, but their after-dinner calorie consumption on the weekend was not significantly different from that at baseline.
• On average, participants in the sleep restricted groups each gained 3 pounds by the end of the study.

“When we don’t get enough sleep, we also are expending more energy,” said coauthor Kenneth Wright Jr, PhD, director of the Sleep and Chronobiology Laboratory at the University of Colorado. “That’s a signal for us to eat more. The problem is we don’t have to forage for food. We can go right to the kitchen.” In an earlier study, Wright found that insufficient sleep increased total daily energy expenditure by around 5%, but energy intake, especially at night after dinner, more than made up for that.Questions Without Answers

The study does not answer a couple of big questions: Could sleeping in on the weekend make up for only a night or 2 of sleep loss during the week? And might the metabolic changes be even worse in people who aren’t young or healthy?

“These were super-healthy people,” Wright said. “That’s what makes this even scarier.”

Research is needed into the effects of sleep restriction and weekend makeup sleep on other populations, he said.

Wright said he and his coauthors were surprised to see that in the weeknight sleep-restricted group, men slept more on the weekend than women. While both men and women slept longer on Friday night than they had at baseline, only men did on Saturday night. “What we do know as a general rule is that women are at a higher risk for insomnia than men,” he said.The Upshot

“Sleep is pretty fundamental, and when we don’t get enough, it will disturb a lot of our physiology,” Wright said. “It’s kind of like smoking: The consequences are long term.”

And, he said, his study suggests that yoyo sleeping—trying to compensate on the weekends for too-little slumber during the week—is probably not going to prevent those long-term consequences and might even make them worse.