The health risks for obesity and fairly well known. Diabetes, heart attacks and hypertension, it's even been linked to certain types of cancer. But now there's even more bad news: It appears that being fat makes it harder to sleep. And the vicious cycle: sleep deprivation can increase your craving for food.

Johns Hopkins University has conducted some research that shows those who sleep poorly are more likely to have weight problems than sound sleepers. Additionally, it showed that high-fat diets can alter sleep cycles and that hormones controlling our appetites can rise and fall with the quality of our sleep.

Sleep, good sound sleep, enough sleep, is becoming an increasingly scarce item in today's fast-paced, caffeinated society. A scant fifty percent of all U.S. adults said they consistently got seven to eight hours of sleep (from the National Sleep Foundation study conducted in 2005). One in six said they got less than six hours a night.

Poor diet and nutrition, the easy availability of junk food, lifestyles that have little or no physical exercise are all obvious causes of the epidemic of obesity in our nation. But would obesity be less of a problem if people addressed their sleep problems before gaining those extra pounds?

It's a logical link: If you don't sleep well, you're less likely to exercise and maintain a healthy diet.

Obesity also increases the risk of sleep apnea, a common disorder in which the airway is repeatedly obstructed during sleep, making it difficult to breathe.

Researchers have uncovered intriguing evidence of a possible hormonal connection. At the University of Chicago scientists found that when 12 young men slept only four hours a night for two nights, it raised their levels of a hunger-stimulating hormone called ghrelin and lowered levels of leptin, a hormone that can suppress hunger.

As well, researchers at Stanford and the Howard Hughes Medical Institute reported that patients with sleep disorders who slept only five hours a night had higher ghrelin and lower leptin levels than average sleepers.

University of Michigan researchers found that sixth-graders were much more likely to be overweight if they had not been sleeping well - either while they were in sixth grade or three years earlier.

Mice were fed a diet made up of 45 percent fat - about 15 percentage points more than experts recommend, at Northwestern University. Researchers found that the high-fat diet extended sleep cycles, so the mice essentially stayed awake longer each day.