concealment writes: "Perhaps some of the best-documented effects of sleep deprivation on weight are based on two powerful hormones: ghrelin and leptin. Ghrelin is involved in sending hunger signals and leptin helps to tell you that you are full. In one study, after just two consecutive nights of four-hours' sleep, test subjects had a 28 percent higher ghrelin (hunger) hormone level and 18 percent lower leptin (satiety) hormone level in their blood compared with subjects who had spent 10 hours a night in bed. In the same study, for those who were sleep deprived, "self-reported hunger and appetite ratings significantly increased by 24 percent and 23 percent, respectively," noted the authors of the review paper, which was led by Julie Shlisky, a researcher at The New York Obesity Nutrition Research Center at Saint Luke's-Roosevelt Hospital Center. "The greatest increase in appetite rating was for energy-dense, high-carbohydrate foods," Shlisky and her co-authors noted."