men, lack of sufficient sleep leads to elevated levels of ghrelin, a hormone that stimulates appetite. In women, on the other hand, ghrelin levels aren’t influenced by lack of sleep, but levels of GLP-1, an appetite-suppressing hormone, are. Granted, such a subtle difference may seem insignificant since the overall result of eating more occurs either way, but it goes to show how little we know about the entire biochemistry of the human body in response to sleep.