That’s the startling outcome of a randomized trial that asked young, overweight adults who typically slept less than six and a half hours to try to sleep about eight and a half hours a night for two weeks.
Some of the study participants cut their intake by 500 calories each day, the study found.
“This is almost like a game changer for weight loss or weight maintenance,” said study author Dr. Esra Tasali, an associate professor of medicine who directs the Sleep Research Center at the University of Chicago.
The researchers projected their findings into the future. They found that eating 270 fewer calories a day would translate to a loss of 26 pounds over three years, all by doing nothing more than getting additional sleep.
“A small intervention you can do to yourself to increase or preserve your sleep duration so you are not sleep deprived can have an significant impact on healthy weight,” Tasali said.
One of the strengths of the study was the fact that it happened in a real-world setting, not a sleep lab, and used an objective urine test to measure calories instead of relying on people’s recall of what they ate.
“This is a very well done study answering an important question,” said Dr. Bhanuprakash Kolla, a sleep psychiatrist and neurologist in the Center for Sleep Medicine and the Division of Addiction Medicine at the Mayo Clinic in Rochester, Minnesota. He was not involved in the study.
“They clearly showed that as you increase the amount of sleep, energy intake reduced and this in turn led to modest reductions in weight,” Kolla said. “It is likely that if this were extended, there could be more significant changes in weight.”
Sleep and hunger are related
Just how does sleeping longer help you lose weight? One reason is the impact lack of sleep has on two key hormones that control hunger and satiety: ghrelin and leptin.
Ghrelin stimulates hunger and has been shown to increase with sleep deprivation. Its partner, leptin, tells us when we are full.
“Leptin has been shown to decrease with sleep restriction. Therefore when we are sleep deprived we have less of this hormone and therefore less of a brake on our appetite,” Kolla said.
And it’s not just people who are overweight who find themselves craving carbs and adding pounds when they are sleep deprived, said Kristen Knutson, an associate professor of sleep and preventive medicine at the Northwestern University Feinberg School of Medicine, who was not involved in the study.
“Studies that observed increased appetite after sleep loss were in people who were not overweight. Getting sufficient sleep has health benefits for everyone regardless of body weight,” Knutson said.
Another way poor sleep impacts our eating choices can be found in the brain’s reward centers, the spot that gives us pleasurable feelings we want to repeat.
“The reward centers in the brain get more activated when you are sleep deprived, which increases your craving for carbohydrates or junk food or a higher overall food intake,” Tasali said.
Then there’s the problem of insulin resistance, which increases with sleep deprivation and leads to weight gain.
“Several laboratory studies have shown that if you were to do a sugar tolerance test in the morning to sleep-deprived individual versus well-rested individual, you would see a pre-diabetic, insulin-resistant state in the morning,” Tasali said.
An easy intervention
How difficult was it for people to add more sleep to their lives? Not that hard at all, Tasali said. Each person underwent an hour-long counseling session about their sleeping style.
“It was very personalized, focused on trying to review people’s lifestyles, their work-related limitations, their family members, their pets, children and bedtime routines,” she said. “Then we talked to them about improving their sleep hygiene, such as putting away electronics before bed.”
Sleep experts advise that any blue light emitting devices — smartphones, laptops and televisions, to name a few — be put away 45 minutes to an hour before bed. That’s because blue light stops the release of melatonin, the body’s sleepy time hormone.
Other sleep hygiene tips include sleeping in a cool bedroom (about 60 to 67 degrees Fahrenheit or 15 to 20 degrees Celsius); skipping spicy food and alcohol before bed; dampening sounds; and having a soothing bedtime ritual, which could include taking a warm bath or shower, reading a book, listening to soothing music, deep breathing, yoga, meditation, or light stretches.
Tasali said she saw changes after just one week of the two-week sleep improvement program.
“Some of them said to me, ‘I thought I was going to be less productive. You’re giving me so much time in bed, how am I going to do all this work that I’m supposed to do?’ And at the end of the two weeks they kept telling me that they were more productive, because they were more energized and more alert.”
One of the study’s limitations, Kolla said, is that none of the subjects suffered from insomnia or other major sleep disorders, which impact millions of people.
“These are only subjects who do not have sleep disturbances but have what we would call behaviorally induced insufficient sleep,” he said. “While the goal was to extend to 8.5 hours, it is quite likely that a majority of people do not require that much amount of sleep. So future work must look at participant-specific information to see who is likely to benefit from this kind of intervention.”
Despite those limitations, he said it’s clear that people who are attempting to lose weight should pay attention “to the amount of sleep that they are getting — avoiding voluntary sleep deprivation is going to play an important role.”
