The Sleep Diet? Dream on…“Sleep: As important as diet and exercise, only easier,” proclaims the National Sleep Foundation on a refrigerator magnet. How true, yet between 1960 and 2010, the average night’s sleep for adults in the United States dropped from eight hours to six and half.
Much has been written about the hazards of this sleep debt. Now new research shows that lack of sleep may also be making Americans fatter. While doctors have long known that hormone levels are affected by sleep, it is only recently that appetite has been linked to this picture.
Here’s how it works: The hormones leptin and ghrelin work in balance with each other to control feelings of hunger and fullness. Ghrelin is produced in the gastrointestinal tract and stimulates appetite. Leptin is produced in fat cells and sends signals to the brain when a person is full.
When a person doesn’t get enough sleep, leptin levels drop so s/he doesn’t feel as satisfied after eating. At the same time, gehrlin levels rise from lack of sleep, meaning the person’s appetite is being stimulated. This combination sets the stage for overeating which may lead to weight gain.
Sleep researcher Michael Breus, Ph.D., has found, “Once a person is not as tired, they don’t need to rely on sweet foods and high carbohydrate snacks to keep them awake—and that automatically translates into eating fewer calories.”
A Stanford University study found that those who slept less than eight hours per night not only had lower levels of leptin and higher levels of gherlin but they also had higher levels of body fat. Another study by Harvard researchers involving 68,000 middle-aged women found that those who slept five hours or less per night weighed 5.4 pounds more, and were 15 percent more likely to be obese, compared to the women who slept seven hours per night.
Lack of deep sleep may also affect a group of neurons in the hypothalamus of the brain, where another hormone, orexin, is involved in regulating feeding behavior. So it may be more than coincidence that Americans have gotten fatter while the amount of sleep has declined.
Some people with health or other issues may need medical consultation to address their sleep problems. For the rest of you (you know who you are), turn off the TV, send your last email, stop texting, close your book, and get a full night’s sleep. Your waistline will thank you.
Sima Michaels Dembo
Bouchez, Colette, “The Dream Diet: Losing Weight While You Sleep,” WebMD, Sleep Disorders Center, reviewed January 1, 2007, WebMD
Brody, Jane, “A Good Night’s Sleep Isn’t a Luxury; It’s a Necessity,” New York Times, May 30, 2011.
“People Who Eat and Sleep Late May Gain Weight,” National Sleep Foundation website, SleepFoundation