More and more people are overweight or obese. The cause is clear, says researcher Esra Tasali, director of the Sleep Center from the University of Chicago. “The current obesity epidemic, according to experts, can mainly be explained by people consuming more calories.” Limiting the number of calories consumed is – as anyone who has ever followed a diet can confirm – not so easy. But Tasali and colleagues have now found a surprisingly simple way to significantly cut calorie intake: go to bed on time.

Previous research

The idea that bedtime influences our eating behavior is of course not entirely new. “Previous lab research has shown that sleep deprivation leads to increased hunger and appetite and increased food intake and therefore weight gain,” Tasali said. It raised an interesting question: Could increasing sleep duration lead to a reduction in food intake and eventually even weight loss?

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New study

To find out, Tasali and colleagues gathered 60 overweight young subjects who were used to sleeping less than 6.5 hours a night. The sleep routine and calorie intake of all subjects was monitored for two weeks. Then the group was divided in two: one group received some sort of sleep training, while the other group (which acted as a control group) did not undergo it. The training was aimed at increasing the duration of sleep. “We simply gave the individuals advice on good sleep hygiene, discussed their own personal sleep environment and offered tailored tips on things they could do differently to help them sleep longer,” Tasali says.

After half of the subjects had completed the sleep training, all subjects were followed again for two weeks. They also looked at their sleep routine and calorie intake. And it soon became clear that the sleep training was paying off. “We saw that after just one coaching session, the subjects were already able to adjust their bedtime habits so that they slept longer.” On average, these test subjects were able to extend their night’s sleep by 1.2 hours with the help of the recommendations. Things got even more interesting, however, when the researchers compared the calorie intake of the trained subjects with that of the control group. On average, the group that now slept considerably longer than the control group took in about 270 calories less per day. That is considerable: in itself enough to lose about 12 kilos over a period of three years – assuming that the extended sleep duration continuously has the same effect on calorie intake over a period of three years.


“It’s not just because people (due to the longer sleep duration, ed.) have less time to eat,” emphasizes Talasi when we ask her how a better night’s sleep affects calorie intake. “When you wake up rested, your metabolism and other systems in your body are better regulated. Your appetite-regulating hormones have decreased and your brain is telling you to eat less and feel less hungry. In addition, circadian factors (i.e. factors associated with our biological 24-hour rhythm, ed.) may also play a role.”

New tools

The research could radically change our view of weight loss, Tasali believes. “Healthy sleep habits could be a new tool in the fight against the obesity epidemic. After all, losing weight or maintaining a healthy weight is all about behavior and healthy sleep habits could be a new tool people can use to feel less hungry and consume fewer calories.” In the future you could therefore imagine that in addition to attention for food and exercise, weight loss programs also pay attention to the importance of a good night’s sleep. “That can really help people trying to lose weight.”

More research is needed before that, Tasali acknowledges. The current study is small and the subjects were followed for only four weeks. “More and longer-term studies are needed to better understand the link between sleep, energy regulation, and weight.” In the meantime, however, it never hurts to take a critical look at your bedtime. “Getting enough sleep has so many benefits, not only for the brain, but also for the rest of the body.” In fact: “A good night’s sleep has benefits for every cell in your body.”