Tuesday, April 10, 2012

One More Reason to Get Checked: Sleep Deprivation Can Cause Weight Gain

It’s no surprise that I use my blog as a forum to educate you on various sleep disorders, and the many reasons to get them diagnosed and treated properly. At the risk of sounding alarmist, not getting a sleep issue checked out—even one you may think is fairly benign—can have dire consequences.

Conditions such as sleep apnea that cause sleep deprivation are linked to poor concentration and memory, increased risk of diabetes, hypertension and high blood pressure, heart attacks and strokes, depression and sexual dysfunction.

As if these reasons aren’t enough to scare you into getting tested, here’s another one that just came out: Lack of sleep is now linked to overeating, and as a result, weight gain. That information was just announced at the American Heart Association’s Epidemiology and Prevention/Nutrition, Physical Activity and Metabolism 2012 conference in San Diego.

To be more specific, according to the study’s abstract, sleep is an important regulator of metabolism and energy expenditure. When acute sleep deprivation occurs, the hormone leptin is reduced, while the hormone ghrelin is increased, promoting caloric intake, but not energy expenditure. The likely result is weight gain.

A quick lesson in endocrinology:

Leptin and ghrelin are appetite hormones. Leptin helps regulate hunger, appetite, and metabolism. When you have low levels of leptin in the body—perhaps due to sleep deprivation—the hormone will tell receptors in the hypothalamus of the brain, “Hey, I’m hungry, feed me.” Normal healthy levels of leptin, on the other hand, will let the brain know that you’ve had enough and are no longer hungry. 

Ghrelin is known as the hunger hormone because its job is to tell the hypothalamus when you are hungry and need to eat. That is why ghrelin levels are elevated in the body when you are hungry, and decrease after you have eaten. Ghrelin also promotes fat storage, and has been linked to the accumulation of abdominal fat.

It stands to reason, then, that if sleep deprivation reduces leptin—causing you to feel hungry—and increases ghrelin—also causing you to feel hungry and eat, then sleep deprivation is likely to lead to overeating and weight gain.

So, how did the researchers come to this conclusion?

Virend Somers, M.D., Ph.D., professor of medicine and cardiovascular disease at the Mayo Clinic, Rochester, Minnesota and his colleagues conducted an eight night sleep test on 17 people—11 men and six women—between the ages of 18 and 40.

Eight of the subjects in the “random group” were made to sleep less than they normally do, while the other nine in the “control group” slept their normal amount of time.

All subjects were able to eat as much as they wanted throughout the testing periods, and their daily caloric intake was measured. In addition, their daily sleep times and energy expenditures were measured, and their blood was collected at the end of the test period.

The results of the test are interesting: The sleep deprived group—who slept one hour and 20 minutes less than the control group per night—ate around 549 more calories per day than the normal sleep group. However, the sleep deprived group who ate more did not expend much more energy than the normal sleep group.

The conclusion again is: Less sleep, plus more calories and no increased activity equals more weight gain. It’s a vicious cycle. So let’s turn this equation around. When you sleep well and get enough rest, you help your body to function properly, including your appetite, metabolism and the hunger hormones mentioned above.

And so I continue my tireless crusade against sleep disorders. If you’re having trouble sleeping, from sleep apnea, snoring or some other disorder, get it checked out and treated by a qualified sleep doctor. Doing so could save you a lot, including a few notches around your belt.

To read the abstract of the study, see Insufficient Sleep Increases Caloric Intake but not Energy Expenditure.