There are a number of major studies that show the connection between sleeping and appetite. And much like everything else in your body, both sleep and appetite are controlled by your hormones. Specifically, it’s all about the balance and timing of leptin and ghrelin into your bloodstream .
Ghrelin is the hormone that’s produced in the stomach and released when you are hungry. It increases your appetite and tells your brain you need to eat. Leptin is produced in your fat cells and when released, tells your brain that you’re full. At which point your appetite decreases and your satiation, or fullness increases.
Stanford scientists studied 1000 volunteers to learn how these two hormones work to connect sleep and weight loss. By comparing the amount of hours volunteers reported sleeping with their ghrelin, leptin, and body fat percentage levels the connection of sleep and weight loss became clear. The data showed that in people that slept less than 8 hours a night, their hormones were unbalanced. In fact, the less than 8 hours a night group had increased levels of ghrelin (which makes you hungry), decreased levels of leptin (which gives the fullness), and higher body fat percentages than the people that slept 8 hours or more. Now you know why they call it beauty sleep.