There are two appetite-regulating hormones: lectin and ghrelin. Lectin lets you know when you had enough to eat; Ghrelin lets you know when you need to eat. It is also important to note the inverse relationship between lectin and ghrelin. When sleep is deprived, ghrelin levels increase (appetite increases). When lectin levels decrease, the body's response to signal us when we are full is compromised and the temptation to overeat is exercised. Although further studies are recommended for definitive results, research indicates a correlation of obesity, increase appetite, increase BMI levels and sleep deprivation.
According to sleep expert Michael Breus, PhD., "When you are sleep deprived, you have less leptin.” More ghrelin plus less leptin equals weight gain.“You are eating more, plus your metabolism is slower when you are sleep-deprived,” During a population-based Wisconsin Sleep Cohort Study, associations among sleep duration (acute and habitual), metabolic hormones, and BMI were investigated, suggesting a number of hormones may mediate the interactions between short sleep duration, metabolism, and high BMI. It was also hypothesized that the two key opposing hormones in appetite regulation, leptin and ghrelin play a significant role in the interaction between short sleep duration and high BMI. (M. ROSICK£, M. KRäEK, M. MATOULEK, Z. JARKOVSK£, J. MAREK,V. JUSTOV£, Z. LACINOV£, 2003)