The phrase "sleep it off" could take on a whole new meaning if Esra Tasali is right.
The University of Chicago researcher is part of a nationwide cadre of scientists who are uncovering evidence that too little sleep could lead to weight gain. If their current studies confirm the link, the next step will be to find out whether sleeping more can help people slim down.
Scientists already know that people who sleep less are fatter.
In an attempt to figure out how sleep and body weight are related, the University of Chicago team measured levels of two hormones that control appetite, leptin and ghrelin in 12 healthy young men. Half the subjects were allowed to sleep only four hours a night, while the others were given 10 hours of shut-eye. The researchers found that sleep deprivation had a significant effect on the two hormones.
"The men who slept only four hours not only were subjectively hungrier," Tasali said, "but we also had objective evidence that hormones were telling their brains they needed more energy."
But all this doesn't yet prove that sleep deprivation actually causes people to gain weight.
"Nobody has shown a cause-effect relation between restricted sleep and obesity," cautioned Dr. Robert Vorona of Eastern Virginia Medical School.
Tasali agreed: "We still need to identify the underlying mechanism [for] what makes people fatter when they're sleep-deprived."
One clue is that her sleep-deprived subjects craved high-carbohydrate foods -- candy, cookies and ice cream -- far more than, say, vegetables or yogurt.
"Maybe that's because the brain uses glucose -- sugar -- as it's main energy source," Tasali said.
Next: Many Americans are obese and don't sleep enough >
