Could the key to weight loss for some people be as simple as getting some extra shuteye?

Possibly. New research suggests that people who don't get enough sleep tend to weigh more -- and that sleep can affect levels of the appetite-regulating hormones leptin and ghrelin.

"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," said Dr. Patrick Strollo, medical director of the University of Pittsburgh Medical Center's Sleep Medicine Center.

Two out of three Americans are overweight, and almost one in five are obese, according to the U.S. Centers for Disease Control and Prevention. 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 Virginia conducted two studies, each included 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," said Dr. Michelle May, author of "Am I Hungry? What To Do When Diets Don't Work."

But, she said, "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, May said.

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's time to stop eating because the stomach is full, decreased by 18 percent during the two-day study period. Levels of another hormone, ghrelin, which 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," said 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."

May agreed, 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.

"Getting enough sleep is the best way to prevent sleep deprivation from contributing to weight gain," May advised. "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."

Strollo said 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 said, 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 don't take long vacations, if you feel that you're not fully functional all day, or that you're doing things to stay awake, like a double-espresso shot, you're probably not getting enough sleep, he said.

May added that it's important to remember that "healthy eating, physical activity and sleep are not luxuries, they are necessities."

More information

To learn more about the connection between sleep and your weight, visit the National Sleep Foundation