A study at UChicago and the University of Wisconsin–Madison looked into improving people's sleep habits, and found that more sleep had a knock-on effect on caloric intake.
The study (opens in new tab) took the form of a four-week-long randomised clinical trial involving 80 overweight adults who typically slept less than 6.5 hours a night. After a sleep counselling session, they were able to increase their sleep duration by an average of 1.2 hours a night, bumping it up over the typical 8-hour benchmark.
With no other prescribed lifestyle changes, participants also saw their overall caloric intake decrease by an average of 270 calories per day, with lowering their intake by up to 500 calories a day. They also recorded a negative energy balance – i.e. one where caloric intake is less than calories burned. Based on those average numbers, over three years that would translate to around 12kg or 26lb of weight loss, potentially just from improving sleep hygiene.
Previous studies have shown that sleep restriction can have knock-on effect on appetite and lead to increased food consumption, Esra Tasali, who headed up the study, told UChicago Medicine (opens in new tab). That prompted the question if increased sleep could have the opposite effect.
Interestingly, the research took a 'real world' approach: participants followed their normal lifestyle, with no manipulation or control of their diet or exercise regime (“This was not a weight-loss study,” said Esra). The only self-monitoring was sleep, logged using a sleep tracker.
“Most other studies on this topic in labs are short-lived, for a couple of days, and food intake is measured by how much participants consume from an offered diet,” Esra told UChicago Medicine. “In our study, we only manipulated sleep, and had the participants eat whatever they wanted, with no food logging or anything else to track their nutrition by themselves.”
Another surprising takeaway was that the participants required very minor intervention to significantly improve their sleep duration. After just a single counselling session, participants increased their average sleep duration by over an hour a night. One key change, Esra noted, was to limit use of electronic devices before bedtime. For more tips, head to our article on how to sleep better at night.
"If healthy sleep habits are maintained over longer duration, this would lead to clinically important weight loss over time," continues Esra. "Many people are working hard to find ways to decrease their caloric intake to lose weight – well, just by sleeping more, you may be able to reduce it substantially."