Getting adequate sleep could be key to fighting growing rates of obesity around the world, according to a study published in JAMA Internal Medicine, which focused solely on improving sleep duration in overweight individuals.
Understanding the underlying causes of obesity and how to prevent it is the best way to fight obesity, according to first author Dr Esra Tasali. “The current obesity epidemic, according to experts, is mostly explained by an increase in caloric intake, rather than lack of exercise,” she said.
In a randomised clinical trial with 80 adults, published in JAMA Internal Medicine, researchers found that young, overweight adults who habitually slept fewer than 6.5 hours a night were able to sleep for 1.2 hours longer after a personalised sleep hygiene counselling session. The sleep intervention was intended to extend time in bed duration to 8.5 hours and, compared to controls, the increased sleep duration also reduced participants’ overall caloric intake by an average of 270 kcal (calories) per day.
“Over the years, we and others have shown that sleep restriction has an effect on appetite regulation that leads to increased food intake, and thus puts you at risk for weight gain over time,” said Tasali. “More recently, the question that everyone was asking was, ‘Well, if this is what happens with sleep loss, can we extend sleep and reverse some of these adverse outcomes?”
The study examines the effects of sleep extension on caloric intake but also does so in a real-world setting, with no influence on participants’ diets. Participants slept in their own beds, tracked their sleep with wearable devices, and otherwise followed their normal lifestyle without any instructions on diet or exercise.
“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,” said Tasali. “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.”
Instead, to objectively track participants’ caloric intake, investigators relied on the “doubly labelled water” method to track change in energy stores, which uses isotopes of hydrogen and oxygen in drinking water. “This is considered the gold standard for objectively measuring daily energy expenditure in a non-laboratory, real-world setting and it has changed the way human obesity is studied,” said Professor Dale A. Schoeller, senior study author and pioneer of the method.
Overall, individuals who increased their sleep duration were able to reduce their caloric intake by an average of 270 kcal per day – which would translate to roughly 12 kg of weight loss over three years if the effects were maintained over a long term.
Perhaps the most surprising aspect of the study was the intervention’s simplicity. “We saw that after just a single sleep counselling session, participants could change their bedtime habits enough to lead to an increase in sleep duration,” said Dr Tasali. “We simply coached each individual on good sleep hygiene, and discussed their own personal sleep environments, providing tailored advice on changes they could make to improve their sleep duration. Importantly, to blind participants to sleep intervention, recruitment materials did not mention sleep intervention, allowing us to capture true habitual sleep patterns at baseline.”
Even though the study did not systematically assess factors that may have influenced sleep behaviour, “limiting the use of electronic devices before bedtime appeared as a key intervention,” said Dr Tasali.
Following just a single counselling session, participants increased their average sleep duration by over an hour a night. Despite prescribing no other lifestyle changes, most participants had a large decrease in how much they ate, with some participants’ intake reduced by 500kcal per day.
The subjects were only involved in the study for a total of four weeks, with two weeks for gathering baseline information about sleep and caloric intake, followed by two weeks to monitor the effects of the sleep intervention.
“This was not a weight-loss study,” said Dr Tasali. “But even within just two weeks, we have quantified evidence showing a decrease in caloric intake and a negative energy balance – caloric intake is less than calories burned. If healthy sleep habits are maintained over longer duration, this would lead to clinically important weight loss over time. 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.”
Source: University of Chicago Medicine
