Ah, sleeping in. It’s truly a luxury appreciated around the world. But those glorious Saturday morning lie-ins don't just affect your mood and help you feel refreshed - sleep duration is also important for longevity and better health.
Research by the Stress Research Institute at Stockholm University found that adults under the age of 65 who get five or fewer hours of sleep for seven days a week have a higher risk of mortality than those who consistently get six or seven hours of sleep.
However, the study also found that individuals who only got a few hours’ sleep each day during the week but enjoyed a long lie-in at weekends had no raised mortality risk, compared with those who consistently slept six or seven hours a night.
How much longer do you sleep at the weekend? Across the pond, the average American sleeps longer on days off, by about 40 minutes, according to a survey by the National Sleep Foundation.
The effects of sleep deprivation
Chronic lack of sleep leads to a higher risk of heart disease, kidney disease, high blood pressure, diabetes, and stroke. Not getting enough sleep may also change our body composition by causing the body to shed muscle mass instead of fat.
Could weekend catch-up sleep reverse these effects? If so, how much sleep is required? These have been open questions in the field of sleep research for some time, according to Josiane Broussard, PhD, an Assistant Research Professor at the University of Colorado Boulder. “There was no real consensus as far as how many nights you needed or how much total sleep was needed to recover,” she says.
Recently, Broussard and other researchers have started to find answers.
How sleeping in on the weekends benefits health
Benefit #1: Lower diabetes risk.
Researchers at UCLA and the University of Sydney in Australia found that among chronically sleep-deprived men, getting three nights of catch-up sleep (about 10 hours per night) led to improvements in insulin sensitivity and other markers of diabetes risk. Broussard led a study that found similar effects after just two nights of recovery sleep, as would be typical of weekends.
Benefit #2: Lower BMI.
People who get weekend catch-up sleep have lower body mass index, according to a large-scale study published in a July 2017 issue of Sleep. Of the 2,156 male subjects followed, the 932 men chosen to sleep in on weekends had a lower BMI than the subjects who were not lucky enough to be chosen to sleep in. Their BMIs were 22.8 vs. 23.1 respectively. The best part: the decrease was proportional, meaning that the more catch-up sleep the study subjects experienced, the lower their BMI.
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Benefit #3: Lower hypertension risk.
A 2013 study published in the journal Sleep Medicine looked at the sleep habits of 2,782 adults. It found that those who slept less than 6 hours per night had an increased risk of hypertension (high blood pressure) compared to those sleeping 7 to 8 hours a night. Fortunately, that risk could be partly reversed with as little as one hour of weekend catch-up sleep, the researchers concluded.
A word of caution...
You don’t want to sleep so late that you’ll be out of sync come Monday morning — a phenomenon known as “social jet lag” that can cause its own problems. Michael A. Grandner, PhD, an Assistant Professor at the University of Arizona, conducted a study that found each hour of social jet lag corresponded with an 11 percent increase in the likelihood of heart disease (not to mention more sleepiness, fatigue and depression). In other words, making up the hours of sleep you get isn’t totally foolproof.
So what’s the right thing to do? Broussard offers this guidance: “Try to get enough sleep every single night if you can,” she says. “If you absolutely can’t, then you should protect those recovery sleep opportunities whenever you have them.”