There are two kinds of people in the world. There are those who leap out of bed at 8.30am on a Saturday morning, ready to tackle their weekend schedule of Instagrammable breakfast dates, art exhibition jaunts, shopping trips and yoga classes.
Then there are those who rarely peel open an eye until well past noon – and even once awake, they’ll usually stay wallowing under the duvet for as long as possible.
If you’re a member of the latter category, we have good news for you. Recent research claims that catching up on sleep at the weekends can make people smarter and healthier, with a correlation found between longer lie-ins and lower body mass indexes (BMIs).
The study, published in the journal Sleep, was conducted by medical researchers in South Korea. They recruited a random sample of more than 2,000 participants aged between 19 and 82, and interviewed them about their weekday and weekend sleep habits, height and weight, and mood and medical conditions.
It was discovered that people who didn’t get enough shut-eye during the week, but who slept in on weekends, generally had slightly lower BMIs than those who didn’t treat themselves to a lie-in on Saturday or Sunday.
Someone’s BMI (a numerical score which takes into account their height and weight) is a quick and easy way for medical professionals to determine whether someone is underweight, of normal weight, overweight or obese.
In addition, the more catch-up sleep a person got on weekends, the lower their BMI tended to be, with each extra hour in bed linked to a 0.12 decrease in BMI.
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Dr Chang-Ho Yun, the lead author on the study, tells Reuters Health that not getting enough sleep can disrupt hormones and metabolism and increase the risk of obesity.
“Short sleep, usually causing sleep debt, is common and inevitable in many cases, and is a risk factor for obesity, hypertension, coronary heart disease, as well as mortality,” he says.
This is in part because short sleepers “tend to eat more meals per day, snack more, engage in more screen time and may be less likely to move due to increased sensations of fatigue when not rested,” according to Jean-Philippe Chaput of the University of Ottawa.
The South Korean study also suggests that indulging in a lie-in can boost brain power. Tiredness is connected to poorer short-term memory function and a feeling of mental ‘sluggishness’ – so getting a bit of extra sleep at the weekend allows your brain to start to process information it wasn’t able to during your hectic, sleep-deprived working week.
So there you have it: the perfect excuse for hitting that snooze button come Saturday.