I suffer from gastric reflux, so this was interesting — How To Treat Heart Burn, Acid Reflux & Stomach Pain :
… avoid lying down with a full stomach, which can increase the production of gastric acid and cause that reflux of the stomach contents.
Typically, it can take up to four hours for 90% of a solid meal to move forward out of the stomach. … So you're still going to have that acid, whirling around your stomach, after a couple of hours. And if you try and go to sleep, then it's no wonder you're going to get this reflux as well.