Sleep more to weight less?: Research from controlled trials is accumulating to suggest that just skipping a couple hours of sleep could make for big--and not so great--biological consequences for your body. Image: iStockphoto/iPandastudio
Getting seven to eight solid hours of sleep each night might seem an almost impossible luxury to many people. But not getting enough sleep is known to impair mental function and increase the risk for heart disease, among other ill effects. Accumulating evidence also suggests that even short-term, partial sleep deprivation could pave the way for weight gain and other negative metabolic consequences.
More than 28 percent of adults in the U.S. report that they get less than six hours of sleep a night, with this cumulative deprivation becoming more common in the past three decades. And now that more than 35 percent of U.S. adults are currently obese, researchers have been searching for potential links between the two conditions, in hopes of reducing the increasing health and economic burden of obesity. Establishing lack of sleep as a risk factor for weight gain could have important clinical and public health effects, possibly allowing people to make simple lifestyle changes to improve their metabolic health.
A new report, published online October 24 in the Journal of the Academy of Nutrition and Dietetics, reviews 18 carefully controlled laboratory studies that tested human subjects' physiological and behavioral responses to sleep deprivation as they relate to metabolic health.
Reena Mehra, an associate professor of medicine who studies sleep and health at Case Western Reserve University School of Medicine and who was not involved in the new analysis, notes that the new paper is "a well done review of the experimental data."
The researchers found that studies of people without sleep-related conditions who got consecutive nights of four to six hours of sleep revealed a wide range of negative effects involving appetite hormone signaling, physical activity, eating behavior and even fat-loss rates. "From a population health perspective, this helps to get people to understand that sleep deprivation really does have an impact on your health," Mehra says.
To sleep, perchance to eat less
Perhaps some of the best-documented effects of sleep deprivation on weight are based on two powerful hormones: ghrelin and leptin. Ghrelin is involved in sending hunger signals and leptin helps to tell you that you are full. In one study, after just two consecutive nights of four-hours' sleep, test subjects had a 28 percent higher ghrelin (hunger) hormone level and 18 percent lower leptin (satiety) hormone level in their blood compared with subjects who had spent 10 hours a night in bed. In the same study, for those who were sleep deprived, "self-reported hunger and appetite ratings significantly increased by 24 percent and 23 percent, respectively," noted the authors of the review paper, which was led by Julie Shlisky, a researcher at The New York Obesity Nutrition Research Center at Saint Luke's-Roosevelt Hospital Center. "The greatest increase in appetite rating was for energy-dense, high-carbohydrate foods," Shlisky and her co-authors noted. Other studies found additional increases in fat and saturated fat consumed by those suffering from sleep deprivation. One study also found a change in another eating signal called peptide YY, which is thought to tell the body it is full after eating enough. It dropped off in a group of subjects who had been allowed only five hours in bed for two nights, suggesting that these sleepy subjects would be more inclined to eat more given the opportunity.