Too Little Zzzs, Too Many Pounds

Insufficient sleep linked to obesity in review of research literature

(RxWiki News) In our fast-paced world, sleep is often the first sacrifice of overworked, busy individuals. But getting too little sleep has implications for our health — including our waistlines.

A recent study found research is continuing to support the link between being overweight and not getting enough sleep.

"Get 7 to 9 hours of sleep every night."

The study, led by Julie D. Shlisky, PhD, at the Department of Nutritional Sciences at Pennsylvania State University, aimed to review the research on the link between sleep deprivation and obesity.

To review the research literature, the researchers searched for English-language articles in PubMed between 1996 and October 2011 which related to getting only 4 to 6 hours of sleep each night that did not include sleep disorders such as sleep apnea.

The key words they used included "sleep deprivation, insufficient sleep, reduced sleep, short sleep duration, sleep curtailment" and "weight loss, appetite, metabolic" or "intake."

Out of a total identified 134 total articles, 14 involved actual clinical trials with adults who did not have sleep disorders and related to sleep deprivation and its relationship to weight.

These 14 studies, plus four more added to the review, investigated at least one of the following factors related to weight: calories burned, body composition, appetite or satisfaction, and concentrations of ghrelin or leptin (the hormones that regulate hunger and fullness), glucose, insulin, thyroid or cortisol (another hormone related to metabolism).

Most of the randomized sleep trials had small participant numbers (20 or fewer) which limited the usefulness of the findings.

Overall, the researchers determined there is not enough good research at the moment to fully understand all the mechanisms underlying the link between obesity and insufficient sleep.

According to William Kohler, MD, director of the Florida Sleep Institute in Spring Hill, Florida, one hypothesis about the link between sleep deprivation and weight gain relates to the hormones leptin and ghrelin.

"Leptin is a hormone produced by fat cells," Dr. Kohler said. "It decreases food intake and it increases energy expenditure, and leptin is decreased in sleep deprivation."

Ghrelin is basically the opposite.

"Ghrelin, which makes people hungry, increases food intake and decreases energy expenditure, and it's increased with sleep deprivation," Dr. Kohler said. 

The way sleep deprivation affects these hormones and how they, in turn, affect hunger might be one of the reasons people are more likely to gain weight with less sleep. However, more research is necessary.

The researchers did find evidence that too little asleep appears to lead people to consume more calories and might interfere with the normal functioning of hunger and appetite hormones.

"Clinicians assisting in weight-loss interventions may improve patient outcomes by discussing sleep time within a healthy lifestyle intervention," the authors wrote. "Individuals experiencing voluntary partial sleep deprivation may be able to improve sleep with lifestyle modifications."

They said people trying to lose weight may consider adjusting their sleep schedule to be sure they are getting enough sleep.

"A sleep-deprived individual striving to lose weight may benefit from the introduction of a behavior based component to their intervention aimed at promoting adequate sleep," the authors wrote.

The study was published October 24 in the Journal of the Academy of Nutrition and Dietetics. The researchers received no external funding. One author consults for the International Life Sciences Institute.

Another author serves on the advisory boards for Abunda, the California Walnut Commission, Campbell Soup Company, MonaVie and Unilever and has received research funding from General Mills, The Hershey Company and the Dairy Research Institute.

Reviewed by: 
Review Date: 
October 24, 2012