The Dream Diet: Losing Weight While You Sleep
Can more sleep really help us control our weight? Three top experts
explore the possibilities.
By Colette Bouchez
Lose weight while you sleep. It sounds like something you'd hear on a
late night infomercial -- just around the time you are reaching for that
bag of cookies because, well, you can't sleep.
But as wild as the idea sounds, substantial medical evidence suggests
some fascinating links between sleep and weight. Researchers say that
how much you sleep and quite possibility the quality of your sleep may
silently orchestrate a symphony of hormonal activity tied to your
appetite.
"One of the more interesting ideas that has been smoldering and is now
gaining momentum is the appreciation of the fact that sleep and sleep
disruption do remarkable things to the body -- including possibly
influencing our weight," says David Rapoport, MD, associate professor
and director of the Sleep Medicine Program at the New York University
School of Medicine in New York City.
While doctors have long known that many hormones are affected by sleep,
Rapoport says it wasn't until recently that appetite entered the
picture. What brought it into focus, he says, was research on the
hormones leptin and ghrelin. First, doctors say that both can influence
our appetite. And studies show that production of both may be influenced
by how much or how little we sleep.
In fact, have you ever experienced a sleepless night followed by a day
when no matter what you ate you never felt full or satisfied? If so,
then you have experienced the workings of leptin and ghrelin.
How Hormones Affect Your Sleep
Leptin and ghrelin work in a kind of "checks and balances" system to
control feelings of hunger and fullness, explains Michael Breus, PhD, a
faculty member of the Atlanta School of Sleep Medicine and director of
The Sleep Disorders Centers of Southeastern Lung Care in Atlanta.
Ghrelin, which is produced in the gastrointestinal tract, stimulates
appetite, while leptin, produced in fat cells, sends a signal to the
brain when you are full.
So what's the connection to sleep? "When you don't get enough sleep, it
drives leptin levels down, which means you don't feel as satisfied after
you eat. Lack of sleep also causes ghrelin levels to rise, which means
your appetite is stimulated, so you want more food," Breus tells WebMD.
The two combined, he says, can set the stage for overeating, which in
turn may lead to weight gain.
Studies: Those Who Sleep Less Often Weigh More
How the hormones leptin and ghrelin set the stage for overeating was
recently explored in two studies conducted at the University of Chicago
in Illinois and at Stanford University in California.
In the Chicago study, doctors measured levels of leptin and ghrelin in
12 healthy men. They also noted their hunger and appetite levels. Soon
after, the men were subjected to two days of sleep deprivation followed
by two days of extended sleep. During this time doctors continued to
monitor hormone levels, appetite, and activity.
The end result: When sleep was restricted, leptin levels went down and
ghrelin levels went up. Not surprisingly, the men's appetite also
increased proportionally. Their desire for high carbohydrate,
calorie-dense foods increased by a whopping 45%.
It was in the Stanford study, however, that the more provocative meaning
of the leptin-ghrelin effect came to light. In this research -- a joint
project between Stanford and the University of Wisconsin -- about 1,000
volunteers reported the number of hours they slept each night. Doctors
then measured their levels of ghrelin and leptin, as well as charted
their weight.
The result: Those who slept less than eight hours a night not only had
lower levels of leptin and higher levels of ghrelin, but they also had a
higher level of body fat. What's more, that level of body fat seemed to
correlate with their sleep patterns. Specifically, those who slept the
fewest hours per night weighed the most.
Sleep: You Can't Lose
Until doctors do know more, most experts agree that if you are dieting,
logging in a few extra hours of sleep a week is not a bad idea,
particularly if you get six hours of sleep or less a night. You may just
discover that you aren't as hungry, or that you have lessened your
craving for sugary, calorie-dense foods.
"One thing I have seen is that 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,"
says Breus.
If, on the other hand, you already sleep a lot, or you increase your
sleep and feel even more tired, you should talk to your doctor. Experts
say you may be one of the thousands of people with undiagnosed sleep
apnea.
Says Roca: "As research continues, more and more data comes to the
forefront to suggest that you simply can't cut back on sleep without
paying some price."
SOURCES: David Rapoport, MD, associate professor and director of the
Sleep Medicine Program, NYU School of Medicine, New York City. Michael
Breus, PhD, Atlanta School of Sleep Medicine; clinical director of The
Sleep Disorder Centers of Southeastern Lung Care, Atlanta. Dominic Roca,
MD, director of the Connecticut Center for Sleep Medicine, Stamford
Hospital. Annals of Internal Medicine, 2004; vol 141: pp 846-850. PLOS
Medicine, December 2004; vol 1. Journal of Clinical Endocrinology and
Metabolism; vol 89: pp 5762-5771. American Journal of Physiology --
Heart and Circulatory Physiology, July 2000; vol 279: pp H234-H237.
(c) 2005 WebMD, Inc. All rights reserved.
