First, levels of the stress hormone cortisol will rise. This can keep you awake at night and also affects glucose metabolism, or the way your body stores fat. Moreover, when you sleep less, you tend to eat more because leptin, the hormone that gives your brain the signal 'I'm full, I'm satiated', is suppressed. As the final element in the triple threat, ghrelin levels also rise when you don't sleep well. Ghrelin is also known as the hunger hormone. This hormone is produced in your intestines and makes you crave carbohydrates.