Sleeping-in on weekends linked to lower body weight

Catching up on lost sleep over weekends may help people keep their weight down, according to a study in South Korea.

Not getting enough sleep can disrupt hormones and metabolism and is known to increase the risk of obesity, researchers write in the journal Sleep.

“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,” lead author Dr Chang-Ho Yun of the Seoul National University Budang Hospital told Reuters Health by e-mail.

Sleeping in may be better than napping, as the sleep may be deeper and follows the body’s sleep-wake rhythms more closely, Yun said.

To determine how weekend sleep is related to body weight, the researchers used data from a nationwide survey of more than 2,000 people who ranged in age from 19 to 82 years old. 

In face-to-face interviews, researchers asked participants about their height and weight, weekday and weekend sleep habits, mood and medical conditions.

The study team used this information to determine body mass index (BMI), a measure of weight relative to height, and whether participants engaged in catch-up sleep on weekends.

Weekend catch-up sleep was defined as sleeping more hours on weekend nights compared to weekday nights.

On average, the participants slept 7.3 hours per night and had BMIs of 23, which falls in the healthy range.

About 43 per cent of people slept longer on weekends by nearly two hours than they did on weekdays.

People who slept-in on weekends tended to sleep shorter hours during weekdays, but slept more hours overall across the week.

The researchers’ analysis found that those who slept-in on weekends had average BMIs of 22.8 while those who didn’t engage in catch-up sleep averaged 23.1, which was a small but statistically meaningful difference.

In addition, the more catch up sleep a person got, the lower their BMI tended to be, with each additional hour linked to a 0.12 decrease in BMI.

“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,” said Jean-Philippe Chaput of the University of Ottawa in Canada, who wasn’t involved in the study.

Chaput noted that getting 30 minutes of heart-pumping exercise per day can help improve sleep. 

“Sleep experts say that if people need an alarm clock to wake up it is a sign that they don’t sleep enough,” Chaput said by e-mail.

“The more good behaviours we can have every day [and sustain for the rest of our lives] the better it is for the prevention of chronic diseases and optimising health. Sleep should be one of these priorities,” he said.

“If you cannot sleep sufficiently on workdays because of work or social obligations, try to sleep as much as possible on the weekend. It might alleviate the risk for obesity.”