New research suggests that people who do not get enough sleep tend to weigh more - and that sleep can affect levels of the appetite-regulating hormones leptin and ghrelin.
Dr. Patrick Strollo, at Pittsburgh Medical Center's Sleep Medicine Center, says, "There is a dynamic balance between proper sleep and proper health. Sleep deprivation affects weight and a lot of other things.
"If you cheat sleep, there are a number of consequences, including affecting your hormones, appetite, and mood," he says.
Two out of three Americans are overweight, and almost one in five are obese, according to the Centers for Disease Control and Prevention (CDC).
And, while most people are aware of the relationship of diet and exercise to excess weight, few realize that the amount of sleep they get each night can also affect their weight.
Researchers at the Sleep Disorders Center at Sentara Norfolk General Hospital in Norfolk, Virginia, conducted two studies, each including 1,000 men and women, and they found that those who reported sleeping less tended to weigh more.
Of course, it could be that being overweight might make it harder to get a restful night sleep.
"People who are overweight may have less restful sleep due to heartburn, snoring, or more serious sleep disorders like sleep apnea or night eating syndrome," says Dr. Michelle May, author of Am I Hungry? What To Do When Diets Don't Work.
But, she says, "It works both ways," and that a lack of sleep can affect your weight. Sleep deprivation affects your body chemistry, appetite, and the choices that you make throughout the day.
Another recent study included 12 healthy men in their 20s. Each of the men slept only four hours for two nights.
The study found that levels of leptin, a hormone that tells the brain it is time to stop eating because the stomach is full, decreased by 18 percent during the two-day study period.
Ghrelin, a hormone that turns the hunger mechanism on, increased by 28 percent.
On average, the men reported that their hunger pangs increased by 24 percent.
"Hormones change with sleep loss and deprivation," says Dr. Strollo. "Sleep deprivation can affect appetite and also the type of food that one desires. When you're sleep-deprived, you generally don't crave carrot sticks."
Dr. May agrees, adding, "When you're tired, you're less resilient to stress and other common emotional triggers for eating. When you eat to help you cope with emotions, you're more likely to choose comfort foods like chocolate, ice cream, or chips.
"And, since eating only helps temporarily, you may find yourself reaching for food again and again to try to make yourself feel better," she says.
"Getting enough sleep is the best way to prevent sleep deprivation from contributing to weight gain," advises Dr. May. "When you aren't able to get your Zzzs, pay more attention to how much you eat and how you handle fatigue and stress. A short walk will be a better energy boost than a trip to the candy machine."
Dr. Strollo says that while most people need between seven and eight hours of sleep a night, there are some people who need as many as 10 and others who may do well on just five hours.
The best way to figure out how much sleep you need, he says, is to take a long vacation and after a couple of days of catching up on your sleep debt, see how many hours of sleep you need to wake without an alarm clock.
Since many Americans do not take long vacations, if you feel that you are not fully functional all day, or that you are doing things to stay awake, like a double-espresso shot, you are probably not getting enough sleep.
Dr. May adds that it is important to remember that "healthy eating, physical activity, and sleep are not luxuries, they are necessities."
Always consult your physician for more information.
Experts recommend a healthy diet and exercise to help maintain a healthy weight and a good night's sleep.
Eat five to nine servings of fruits and vegetables daily. A vegetable serving is one cup of raw vegetables or one-half cup of cooked vegetables or vegetable juice. A fruit serving is one piece of small to medium fresh fruit, one-half cup of canned or fresh fruit or fruit juice, or one-fourth cup of dried fruit.
Choose whole grain foods such as brown rice and whole wheat bread. Avoid highly processed foods made with refined white sugar, flour, and saturated fat.
Weigh and measure food in order to be able to gain an understanding of portion sizes. For example, a 3-ounce serving of meat is the size of a deck of cards. Avoid supersized menu items.
Balance the food "checkbook." Taking in more calories than are expended for energy will result in weight gain. Regularly monitor weight.
Avoid foods that are high in "energy density," or that have a lot of calories in a small amount of food. For example, a large cheeseburger with a large order of fries may have almost 1,000 calories and 30 or more grams of fat. By ordering a grilled chicken sandwich or a plain hamburger and a small salad with low-fat dressing, you can avoid hundreds of calories and eliminate much of the fat intake.
For dessert, have fruit or a piece of angel food cake rather than the "death by chocolate" special or three pieces of home-made pie.
Remember that much may be achieved with proper choices in serving sizes.
Accumulate at least 30 minutes or more of moderate-intensity activity on most, or preferably all, days of the week. Examples of moderate intensity exercise are walking a 15-minute mile, or weeding and hoeing a garden.
Look for opportunities during the day to perform even ten or 15 minutes of some type of activity, such as walking around the block or up and down a few flights of stairs.
Always consult your physician for more information.