Sorry to disappoint you on this way. Seriously, how is that even possible. For the longest time we have been told if you want to achieve something you have to work hard for it, right? So by sleeping, have you worked in anyway to have your pot belly disappear? Just so you know there is this saying from way back, NO PAIN NO GAIN! You have to feel pain to get results. All you get from lying on your stomach is a relieving from a backache. What you need to do is start exercising if you do not want the pot belly to grow bigger, situps, squats and stretches will definitely erase the problem and you will also feel good about yourself in the long run. Jogging also will flex your muscles and burn the fats that are concentrated there, a lot of sweating and panting, but results will be achieved.