For many people, missing an hour or two of sleep is no big deal; they stay up for one more episode on Netflix or stay out late on Friday, banking on catching their Z’s over the weekend. But a new study suggests that a Saturday snooze-in isn’t as refreshing as it seems, and there may be no way to reclaim the benefits of those lost hours.
Nicola Davis at The Guardian reports that previous studies have shown that missing sleep can disrupt the metabolism, and boost the chances for developing obesity or metabolic disorders like diabetes. Researchers wondered, however, if people could offset those ill-effects by adding on sleep at the end of the week.
To investigate, researchers at the University of Colorado in Boulder recruited 36 participants between the ages of 18 and 39, each of whom spent a few nights in the sleep lab. One lucky group of eight was allowed to sleep up to nine hours for nine nights. The others were divided into two groups of 14, with all of them getting five or fewer hours of sleep per night. One of those groups, however, was allowed to choose their own bedtime and sleep in after five nights on the short sleep schedule to simulate a weekend of sleeping in.
Most of those allowed to sleep in didn’t rise until around noon. Still, the added hours weren’t enough to make up for the hours lost in previous nights, and on average, participants gained just 1.1 extra hours of sleep on the weekend. Even more, the levels of melatonin, a hormone the body uses to regulate sleep, were more disrupted in those who slept in than those who kept to an abbreviated, but regular sleeping pattern. And while insulin sensitivity in the group that was allowed to sleep on a regular schedule dropped by 13 percent, in the weekend-sleepers it worsened by 9 to 27 percent. The study appears in the journal Current Biology.
CU Boulder sleep physiologist Kenneth Wright, senior author of the paper, says in a press release that disrupting our body clock may be more harmful than losing a few hours of sleep. “It could be that the yo-yoing back and forth – changing the time we eat, changing our circadian clock and then going back to insufficient sleep is uniquely disruptive,” he says.
Shamard Charles at NBC News reports that the sleep deprivation had direct repercussions for participant’s waistlines as well. While those who got a full night’s sleep didn’t change their eating habits, the two groups with restricted sleep tended to snack more than normal. In fact, Peter Hess at Inverse reports the sleep-deprived munched on average 500 after-dinner calories more than their well-rested counterparts.
That’s not unexpected. “We have these hormones called leptin and ghrelin,” Azizi Seixas, sleep researcher at New York University School of Medicine, not involved in the study tells NBC’s Charles. “One is associated with satiety, and the other one increases your appetite. They both go out of whack when you’re sleep deprived… 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.”
So, should we completely banish sleeping in on weekends? In the press release, Wright says that the study seems to indicate that over the long term, making up for lost sleep on weekends is probably harmful for people with irregular sleep schedules. But it’s possible that it could help refresh someone who misses one or two nights of sleep during the work week—though that idea needs more research.
More important, the authors conclude, is sticking to a good sleep habits. “This study demonstrates the importance of getting sufficient sleep on a regular schedule,” Michael Twery, director of the National Center on Sleep Disorders Research, who was not involved in the study, says in the press release. “Frequently changing sleep schedules is a form of stress associated with metabolic abnormalities.”
The upshot? Wright says get at least seven hours of sleep per night, every night, even if it means waiting to watch the season finale tomorrow.