First on this list of sleep-inducing foods comes the all-American favorite that we call fast food. The reason eating a Big Mac or a Whopper makes you tired is because our bodies have to work harder to digest all of that grease and fat. When all of the blood flow has to move to our stomach to accommodate that process, we start to feel tired and want to take a nap. This fatigue is especially true for people with stomach issues. It's no secret that fast food makes us tired, but now you know why.