In today’s day and age, many of us aren't sleeping as much as we should: We stay up late, burning the midnight oil (or streaming the midnight Netflix), but are still forced to wake up early, thanks to all of those societal obligations—like work and school and spin class—first thing in the morning. So when the weekend rolls around, it can be tempting to sleep in, in an attempt to catch up on all those lost hours.
But does catching up on this so-called sleep debt really work? A new study suggests that it might—but experts still say you shouldn’t make a habit of it. For the bottom line on weekend sleep, Health looked at the latest research and spoke with leading researchers in the field. Here’s what we found out.
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Your brain on sleep debt
Sleep doctors have long preached the importance of getting a full night’s sleep—which, for most adults, is somewhere between seven and nine hours a night. Studies show that when people consistently get less than six, it can negatively affect their health, including their metabolism and their cardiovascular system. Even temporary periods of short sleep can lead to impairments in mood and concentration levels.
One recent study, for example, found that when people got less than six hours of sleep a night, they had trouble completing basic tasks: They had a fivefold increase in attention lapses and their reaction time nearly doubled, compared with people who slept seven or more hours, even when they didn’t feel tired or realize that their performance was suffering.
New research may advocate for weekend catch-ups
A study published this week in the Journal of Sleep Research provides a beacon of hope that maybe some of these negative effects can be made up for by getting extra sleep over the weekend. The study followed more than 43,000 adults in Sweden for 13 years and compared death rates in that time period with participants’ self-reported sleep habits.
The researchers found that adults younger than 65 who consistently slept five or fewer hours were 65% more likely to die early than those who slept six to seven hours a night on average. (Sleeping eight or more hours a night was also associated with an increased risk, of 25%.)
But those who reported short sleep during the week and long sleep on the weekends seemed protected: Despite skimping on shuteye Sunday through Thursday nights, they had no increased mortality risk compared to those who consistently got six to seven hours.
“It seems that weekday short sleep may be forgiven by weekend compensation,” lead study author Torbjörn Åkerstedt, a professor of psychology at the Karolinska Institutet, told Health in an email. In other words, he says, it may be healthier in the long run to catch up on lost sleep over the weekend than to keep a shortened sleep schedule all seven days.
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But other experts warn the practice still isn't healthy
These findings seem to contradict another recent study, presented last year at the annual meeting of the Associated Professional Sleep Societies. That study, which has not been published in a peer-reviewed medical journal, found that every hour of “social jet lag” a person experienced on the weekends was associated with a 28% increased likelihood of self-reported fair/poor health, compared with excellent health. (The study was not designed to find a cause-and-effect relationship.)
Social jet lag is a measure of how much a person’s sleep is “shifted” forward or backward on the weekends. If you sleep from 11 p.m. to 7 a.m. on weeknights (midpoint 3 a.m.) and from 2 a.m. to 10 a.m. on weekends (midpoint 6 a.m.), for example, that’s a three-hour shift.
Every hour of shifted sleep was also associated with an 11% increased risk of heart disease, as well as higher scores on fatigue, sleepiness, and depression screenings. The researchers believe that a shifted sleep schedule affects circadian rhythm and hormone levels throughout the day, and that throwing them out of whack could contribute to both physical and emotional health issues.
Åkerstedt says this research makes an interesting correlation, but he also says that catching up on sleep over the weekend doesn’t have to mean shifting your sleep midpoint: It could mean going to bed a little earlier and getting up a little later, rather than staying up super late and sleeping until noon.
Andrew Varga, MD assistant professor of pulmonary critical care and sleep medicine at Mount Sinai Health System, says that the idea that extra weekend sleep might mitigate some long-term health risks is “a totally reasonable conclusion to draw.” But he adds that mortality risk is just one aspect of health, and that there are likely more immediate consequences of lost sleep that a weekend snooze-fest can’t make up for.
“There’s a fair amount of research showing other outcomes, particularly with cognition, and in these areas it’s not clear that you can really catch up so quickly,” he says. Things like memory and concentration can be affected in as little as two or three days of short sleep, he adds, so the weekend may be too late to make up for those effects.
There’s also evidence, says Dr. Varga, that people with shifted sleep schedules—opposite of the body’s natural circadian rhythm—are at higher risk for conditions like heart disease and diabetes. But most research has been done in extreme cases, like shift workers who work overnight and sleep during the day, and not in people who simply sleep a few hours later on the weekends.
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Consistency is still the smartest option
Åkerstedt says his new research suggests that making up for lost sleep on the weekends may be better than never making it up at all. But he does agree with other health experts who say that it’s better to get enough sleep every night.
“Consistency is always key,” he says, as long as it’s consistently an intermediate sleep duration—not too much or too little.
And while he isn’t convinced that sleeping in on the weekends can lead to long-term health risks, he does agree it can make starting the workweek again even harder. “The problem with sleeping in is mainly the Blue Monday effect—that is, fatigue and poor performance,” he says.
Of course, some people really are night owls and have trouble getting to sleep early enough during the week to get their seven to nine hours, says Dr. Varga. If you fall into that camp, he suggests talking to a sleep doctor about ways to adjust your internal body clock rather than trying to make it all up every weekend.
If you steal a few extra hours over the weekend—and doing so doesn’t affect your ability to fall asleep Sunday night—it’s probably not a big deal, says Dr. Varga. But pay attention to why you’re sleeping in, he says: Is it because you’re staying up late, and is that accompanied by drinking or eating more than you normally would?
“Sleep doctors are always going to recommend consistency,” he says. “Try to keep the same bedtime, the same wakeup time, day in and day out, every day,” he says. Of course, life can get in the way—but at least be conscious of when (and why) your schedule is shifting, he adds, and try not to make it a regular habit.